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Analytica Chimica Acta (v.712, #)
A novel ionic liquid monolithic column and its separation properties in capillary electrochromatography by Yu Wang; Qi-Liang Deng; Guo-Zhen Fang; Ming-Fei Pan; Yang Yu; Shuo Wang (pp. 1-8).
Display Omitted► ILs as functional monomer for capillary monolithic column. ► Separation of alkylbenzenes, thiourea analogues, and amino acids. ► The column generate a stable reversed EOF from pH 2.0 to 12.0. ► The column efficiency of 147,000platesm−1 was obtained for thiourea.A novel ionic liquid (IL) monolithic capillary column was successfully prepared by thermal free radical copolymerization of IL (1-vinyl-3-octylimidazolium chloride, ViOcIm+Cl−) together with lauryl methacrylate (LMA) as the binary functional monomers and ethylene dimethacrylate (EDMA) as the cross-linker in binary porogen. The proportion of monomers, porogens and cross-linker in the polymerization mixture was optimized in detail. The resulting IL-monolithic column could not only generate a stable reversed electroosmotic flow (EOF) in a wide pH range (2.0–12.0), but also effectively eliminate the wall adsorption of the basic analytes. The obtained IL-monolithic columns were examined by scanning electron microscopy (SEM) and Fourier transform infrared (FT-IR). These results indicated that the IL-monolithic capillary column possessed good pore properties, mechanical stability and permeability. The column performance was also evaluated by separating different kinds of compounds, such as alkylbenzenes, thiourea and its analogues, and amino acids. The lowest plate height of ∼6.8μm was obtained, which corresponded to column efficiency (theoretical plates, N) of ∼147,000platesm−1 for thiourea. ILs, as a new type of functional monomer, present a promising option in the fabrication of the organic polymer-based monolithic columns in CEC.
Keywords: Capillary electrochromatography; Ionic liquid; Monolithic column; Separation
A novel ionic liquid monolithic column and its separation properties in capillary electrochromatography by Yu Wang; Qi-Liang Deng; Guo-Zhen Fang; Ming-Fei Pan; Yang Yu; Shuo Wang (pp. 1-8).
Display Omitted► ILs as functional monomer for capillary monolithic column. ► Separation of alkylbenzenes, thiourea analogues, and amino acids. ► The column generate a stable reversed EOF from pH 2.0 to 12.0. ► The column efficiency of 147,000platesm−1 was obtained for thiourea.A novel ionic liquid (IL) monolithic capillary column was successfully prepared by thermal free radical copolymerization of IL (1-vinyl-3-octylimidazolium chloride, ViOcIm+Cl−) together with lauryl methacrylate (LMA) as the binary functional monomers and ethylene dimethacrylate (EDMA) as the cross-linker in binary porogen. The proportion of monomers, porogens and cross-linker in the polymerization mixture was optimized in detail. The resulting IL-monolithic column could not only generate a stable reversed electroosmotic flow (EOF) in a wide pH range (2.0–12.0), but also effectively eliminate the wall adsorption of the basic analytes. The obtained IL-monolithic columns were examined by scanning electron microscopy (SEM) and Fourier transform infrared (FT-IR). These results indicated that the IL-monolithic capillary column possessed good pore properties, mechanical stability and permeability. The column performance was also evaluated by separating different kinds of compounds, such as alkylbenzenes, thiourea and its analogues, and amino acids. The lowest plate height of ∼6.8μm was obtained, which corresponded to column efficiency (theoretical plates, N) of ∼147,000platesm−1 for thiourea. ILs, as a new type of functional monomer, present a promising option in the fabrication of the organic polymer-based monolithic columns in CEC.
Keywords: Capillary electrochromatography; Ionic liquid; Monolithic column; Separation
Application of surface plasmon resonance for the detection of carbohydrates, glycoconjugates, and measurement of the carbohydrate-specific interactions: A comparison with conventional analytical techniques. A critical review by Gulnara Safina (pp. 9-29).
Display Omitted► Comprehensive overview of the analytical techniques for the assay of glycoforms is given. ► Special emphasis on surface plasmon resonance (SPR) for the assay of glycoforms is done. ► Different SPR techniques and approaches for the assay of glycoforms are highlighted. ► Critical comparison of the analytical techniques/methods with SPR for the assay of glycoforms is provided.Carbohydrates (glycans) and their conjugates with proteins and lipids contribute significantly to many biological processes. That makes these compounds important targets to be detected, monitored and identified. The identification of the carbohydrate content in their conjugates with proteins and lipids (glycoforms) is often a challenging task. Most of the conventional instrumental analytical techniques are time-consuming and require tedious sample pretreatment and utilising various labeling agents. Surface plasmon resonance (SPR) has been intensively developed during last two decades and has received the increasing attention for different applications, from the real-time monitoring of affinity bindings to biosensors. SPR does not require any labels and is capable of direct measurement of biospecific interaction occurring on the sensing surface. This review provides a critical comparison of modern analytical instrumental techniques with SPR in terms of their analytical capabilities to detect carbohydrates, their conjugates with proteins and lipids and to study the carbohydrate-specific bindings. A few selected examples of the SPR approaches developed during 2004–2011 for the biosensing of glycoforms and for glycan–protein affinity studies are comprehensively discussed.
Keywords: Carbohydrates; Glycoconjugates; Lectins; Surface plasmon resonance; Label-free detection techniques; Carbohydrate–lectin interactions
Application of surface plasmon resonance for the detection of carbohydrates, glycoconjugates, and measurement of the carbohydrate-specific interactions: A comparison with conventional analytical techniques. A critical review by Gulnara Safina (pp. 9-29).
Display Omitted► Comprehensive overview of the analytical techniques for the assay of glycoforms is given. ► Special emphasis on surface plasmon resonance (SPR) for the assay of glycoforms is done. ► Different SPR techniques and approaches for the assay of glycoforms are highlighted. ► Critical comparison of the analytical techniques/methods with SPR for the assay of glycoforms is provided.Carbohydrates (glycans) and their conjugates with proteins and lipids contribute significantly to many biological processes. That makes these compounds important targets to be detected, monitored and identified. The identification of the carbohydrate content in their conjugates with proteins and lipids (glycoforms) is often a challenging task. Most of the conventional instrumental analytical techniques are time-consuming and require tedious sample pretreatment and utilising various labeling agents. Surface plasmon resonance (SPR) has been intensively developed during last two decades and has received the increasing attention for different applications, from the real-time monitoring of affinity bindings to biosensors. SPR does not require any labels and is capable of direct measurement of biospecific interaction occurring on the sensing surface. This review provides a critical comparison of modern analytical instrumental techniques with SPR in terms of their analytical capabilities to detect carbohydrates, their conjugates with proteins and lipids and to study the carbohydrate-specific bindings. A few selected examples of the SPR approaches developed during 2004–2011 for the biosensing of glycoforms and for glycan–protein affinity studies are comprehensively discussed.
Keywords: Carbohydrates; Glycoconjugates; Lectins; Surface plasmon resonance; Label-free detection techniques; Carbohydrate–lectin interactions
A risk-based statistical investigation of the quantification of polymorphic purity of a pharmaceutical candidate by solid-state19F NMR by Samantha J. Barry; Tran N. Pham; Phil J. Borman; Andrew J. Edwards; Simon A. Watson (pp. 30-36).
.Display Omitted► Investigate a quantitative19F solid-state NMR method for polymorphic purity. ► DMAIC framework used to investigate risk factors and reduce variability. ► Analytical method found to directly affect polymorphism. ► Differences in data processing are responsible for variability in the method. ► Specific processing steps implemented to reduce variability.The DMAIC (Define, Measure, Analyse, Improve and Control) framework and associated statistical tools have been applied to both identify and reduce variability observed in a quantitative19F solid-state NMR (SSNMR) analytical method. The method had been developed to quantify levels of an additional polymorph (Form 3) in batches of an active pharmaceutical ingredient (API), where Form 1 is the predominant polymorph. In order to validate analyses of the polymorphic form, a single batch of API was used as a standard each time the method was used. The level of Form 3 in this standard was observed to gradually increase over time, the effect not being immediately apparent due to method variability. In order to determine the cause of this unexpected increase and to reduce method variability, a risk-based statistical investigation was performed to identify potential factors which could be responsible for these effects. Factors identified by the risk assessment were investigated using a series of designed experiments to gain a greater understanding of the method. The increase of the level of Form 3 in the standard was primarily found to correlate with the number of repeat analyses, an effect not previously reported in SSNMR literature. Differences in data processing (phasing and linewidth) were found to be responsible for the variability in the method. After implementing corrective actions the variability was reduced such that the level of Form 3 was within an acceptable range of ±1% ww−1 in fresh samples of API.
Keywords: Fishbone; DMAIC; Variance; Polymorphism; Quantitative; Solid-state; 19; F NMR
A risk-based statistical investigation of the quantification of polymorphic purity of a pharmaceutical candidate by solid-state19F NMR by Samantha J. Barry; Tran N. Pham; Phil J. Borman; Andrew J. Edwards; Simon A. Watson (pp. 30-36).
.Display Omitted► Investigate a quantitative19F solid-state NMR method for polymorphic purity. ► DMAIC framework used to investigate risk factors and reduce variability. ► Analytical method found to directly affect polymorphism. ► Differences in data processing are responsible for variability in the method. ► Specific processing steps implemented to reduce variability.The DMAIC (Define, Measure, Analyse, Improve and Control) framework and associated statistical tools have been applied to both identify and reduce variability observed in a quantitative19F solid-state NMR (SSNMR) analytical method. The method had been developed to quantify levels of an additional polymorph (Form 3) in batches of an active pharmaceutical ingredient (API), where Form 1 is the predominant polymorph. In order to validate analyses of the polymorphic form, a single batch of API was used as a standard each time the method was used. The level of Form 3 in this standard was observed to gradually increase over time, the effect not being immediately apparent due to method variability. In order to determine the cause of this unexpected increase and to reduce method variability, a risk-based statistical investigation was performed to identify potential factors which could be responsible for these effects. Factors identified by the risk assessment were investigated using a series of designed experiments to gain a greater understanding of the method. The increase of the level of Form 3 in the standard was primarily found to correlate with the number of repeat analyses, an effect not previously reported in SSNMR literature. Differences in data processing (phasing and linewidth) were found to be responsible for the variability in the method. After implementing corrective actions the variability was reduced such that the level of Form 3 was within an acceptable range of ±1% ww−1 in fresh samples of API.
Keywords: Fishbone; DMAIC; Variance; Polymorphism; Quantitative; Solid-state; 19; F NMR
One- and two-dimensional gas chromatography–mass spectrometry and high performance liquid chromatography–diode-array detector fingerprints of complex substances: A comparison of classification performance of similar, complex Rhizoma Curcumae samples with the aid of chemometrics by Yongnian Ni; Minghua Mei; Serge Kokot (pp. 37-44).
Display Omitted► GC–MS and HPLC–DAD technique were combined to produce two-way fingerprints for the complex materials. ► Supervised chemometrics methods, LDA, BP-ANN and LS-SVM were used for classification. ► Improved information and discrimination of the objects were obtained from the combined data matrix models.Many complex natural or synthetic products are analysed either by the GC–MS (gas chromatography–mass spectrometry) or HPLC–DAD (high performance liquid chromatography–diode-array detector) technique, each of which produces a one-dimensional fingerprint for a given sample. This may be used for classification of different batches of a product. GC–MS and HPLC–DAD analyses of complex, similar substances represented by the three common types of the TCM (traditional Chinese medicine), Rhizoma Curcumae were analysed in the form of one- and two-dimensional matrices firstly with the use of PCA (Principal component analysis), which showed a reasonable separation of the samples for each technique. However, the separation patterns were rather different for each analytical method, and PCA of the combined data matrix showed improved discrimination of the three types of object; close associations between the GC–MS and HPLC–DAD variables were observed. LDA (linear discriminant analysis), BP-ANN (back propagation-artificial neural networks) and LS-SVM (least squares-support vector machine) chemometrics methods were then applied to classify the training and prediction sets. For one-dimensional matrices, all training models indicated that several samples would be misclassified; the same was observed for each prediction set. However, by comparison, in the analysis of the combined matrix, all models gave 100% classification with the training set, and the LS-SVM calibration also produced a 100% result for prediction, with the BP-ANN calibration closely behind. This has important implications for comparing complex substances such as the TCMs because clearly the one-dimensional data matrices alone produce inferior results for training and prediction as compared to the combined data matrix models. Thus, product samples may be misclassified with the use of the one-dimensional data because of insufficient information.
Keywords: Gas chromatography–mass spectrometry (GC–MS); High performance liquid chromatography–diode-array detector (HPLC–DAD); Two-dimensional fingerprints; Classification; Least squares-support vector machine (LS-SVM); Rhizoma Curcumae
One- and two-dimensional gas chromatography–mass spectrometry and high performance liquid chromatography–diode-array detector fingerprints of complex substances: A comparison of classification performance of similar, complex Rhizoma Curcumae samples with the aid of chemometrics by Yongnian Ni; Minghua Mei; Serge Kokot (pp. 37-44).
Display Omitted► GC–MS and HPLC–DAD technique were combined to produce two-way fingerprints for the complex materials. ► Supervised chemometrics methods, LDA, BP-ANN and LS-SVM were used for classification. ► Improved information and discrimination of the objects were obtained from the combined data matrix models.Many complex natural or synthetic products are analysed either by the GC–MS (gas chromatography–mass spectrometry) or HPLC–DAD (high performance liquid chromatography–diode-array detector) technique, each of which produces a one-dimensional fingerprint for a given sample. This may be used for classification of different batches of a product. GC–MS and HPLC–DAD analyses of complex, similar substances represented by the three common types of the TCM (traditional Chinese medicine), Rhizoma Curcumae were analysed in the form of one- and two-dimensional matrices firstly with the use of PCA (Principal component analysis), which showed a reasonable separation of the samples for each technique. However, the separation patterns were rather different for each analytical method, and PCA of the combined data matrix showed improved discrimination of the three types of object; close associations between the GC–MS and HPLC–DAD variables were observed. LDA (linear discriminant analysis), BP-ANN (back propagation-artificial neural networks) and LS-SVM (least squares-support vector machine) chemometrics methods were then applied to classify the training and prediction sets. For one-dimensional matrices, all training models indicated that several samples would be misclassified; the same was observed for each prediction set. However, by comparison, in the analysis of the combined matrix, all models gave 100% classification with the training set, and the LS-SVM calibration also produced a 100% result for prediction, with the BP-ANN calibration closely behind. This has important implications for comparing complex substances such as the TCMs because clearly the one-dimensional data matrices alone produce inferior results for training and prediction as compared to the combined data matrix models. Thus, product samples may be misclassified with the use of the one-dimensional data because of insufficient information.
Keywords: Gas chromatography–mass spectrometry (GC–MS); High performance liquid chromatography–diode-array detector (HPLC–DAD); Two-dimensional fingerprints; Classification; Least squares-support vector machine (LS-SVM); Rhizoma Curcumae
Testing the performance of pure spectrum resolution from Raman hyperspectral images of differently manufactured pharmaceutical tablets by Balázs Vajna; Attila Farkas; Hajnalka Pataki; Zsolt Zsigmond; Tamás Igricz; György Marosi (pp. 45-55).
Display Omitted► MCR-ALS and PMF provide better spectra and concentration maps than SMMA and SISAL. ► Homogeneous distribution of a component makes curve resolution much less accurate. ► MCR-ALS can be also well used if a component is homogeneously distributed. ► An unknown product can be characterized regardless how it was manufactured. ► Our results show perspectives in the analysis of unknown (illegal) drugs.Chemical imaging is a rapidly emerging analytical method in pharmaceutical technology. Due to the numerous chemometric solutions available, characterization of pharmaceutical samples with unknown components present has also become possible. This study compares the performance of current state-of-the-art curve resolution methods (multivariate curve resolution-alternating least squares, positive matrix factorization, simplex identification via split augmented Lagrangian and self-modelling mixture analysis) in the estimation of pure component spectra from Raman maps of differently manufactured pharmaceutical tablets. The batches of different technologies differ in the homogeneity level of the active ingredient, thus, the curve resolution methods are tested under different conditions. An empirical approach is shown to determine the number of components present in a sample. The chemometric algorithms are compared regarding the number of detected components, the quality of the resolved spectra and the accuracy of scores (spectral concentrations) compared to those calculated with classical least squares, using the true pure component (reference) spectra. It is demonstrated that using appropriate multivariate methods, Raman chemical imaging can be a useful tool in the non-invasive characterization of unknown (e.g. illegal or counterfeit) pharmaceutical products.
Keywords: Micro-Raman; Hyperspectral; Imaging; Chemometrics; Pharmaceutical; Mapping
Testing the performance of pure spectrum resolution from Raman hyperspectral images of differently manufactured pharmaceutical tablets by Balázs Vajna; Attila Farkas; Hajnalka Pataki; Zsolt Zsigmond; Tamás Igricz; György Marosi (pp. 45-55).
Display Omitted► MCR-ALS and PMF provide better spectra and concentration maps than SMMA and SISAL. ► Homogeneous distribution of a component makes curve resolution much less accurate. ► MCR-ALS can be also well used if a component is homogeneously distributed. ► An unknown product can be characterized regardless how it was manufactured. ► Our results show perspectives in the analysis of unknown (illegal) drugs.Chemical imaging is a rapidly emerging analytical method in pharmaceutical technology. Due to the numerous chemometric solutions available, characterization of pharmaceutical samples with unknown components present has also become possible. This study compares the performance of current state-of-the-art curve resolution methods (multivariate curve resolution-alternating least squares, positive matrix factorization, simplex identification via split augmented Lagrangian and self-modelling mixture analysis) in the estimation of pure component spectra from Raman maps of differently manufactured pharmaceutical tablets. The batches of different technologies differ in the homogeneity level of the active ingredient, thus, the curve resolution methods are tested under different conditions. An empirical approach is shown to determine the number of components present in a sample. The chemometric algorithms are compared regarding the number of detected components, the quality of the resolved spectra and the accuracy of scores (spectral concentrations) compared to those calculated with classical least squares, using the true pure component (reference) spectra. It is demonstrated that using appropriate multivariate methods, Raman chemical imaging can be a useful tool in the non-invasive characterization of unknown (e.g. illegal or counterfeit) pharmaceutical products.
Keywords: Micro-Raman; Hyperspectral; Imaging; Chemometrics; Pharmaceutical; Mapping
Characterisation of PDO olive oil Chianti Classico by non-selective (UV–visible, NIR and MIR spectroscopy) and selective (fatty acid composition) analytical techniques by M. Casale; P. Oliveri; C. Casolino; N. Sinelli; P. Zunin; C. Armanino; M. Forina; S. Lanteri (pp. 56-63).
Display Omitted► Characterisation of the Italian PDO extra virgin olive oil Chianti Classico. ► Comparison between non-selective (UV–vis, NIR and MIR spectroscopy) and selective (fatty acid composition) analytical techniques. ► Synergy among spectroscopic techniques, by the fusion of the respective spectra. ► Prediction of the content of oleic and linoleic acids in the olive oils.An authentication study of the Italian PDO (protected designation of origin) extra virgin olive oil Chianti Classico was performed; UV–visible (UV–vis), Near-Infrared (NIR) and Mid-Infrared (MIR) spectroscopies were applied to a set of samples representative of the whole Chianti Classico production area.The non-selective signals (fingerprints) provided by the three spectroscopic techniques were utilised both individually and jointly, after fusion of the respective profile vectors, in order to build a model for the Chianti Classico PDO olive oil.Moreover, these results were compared with those obtained by the gas chromatographic determination of the fatty acids composition.In order to characterise the olive oils produced in the Chianti Classico PDO area, UNEQ (unequal class models) and SIMCA (soft independent modelling of class analogy) were employed both on the MIR, NIR and UV–vis spectra, individually and jointly, and on the fatty acid composition.Finally, PLS (partial least square) regression was applied on the UV–vis, NIR and MIR spectra, in order to predict the content of oleic and linoleic acids in the extra virgin olive oils.UNEQ, SIMCA and PLS were performed after selection of the relevant predictors, in order to increase the efficiency of both classification and regression models.The non-selective information obtained from UV–vis, NIR and MIR spectroscopy allowed to build reliable models for checking the authenticity of the Italian PDO extra virgin olive oil Chianti Classico.
Keywords: Chianti Classico; PDO olive oil; Spectroscopy; Classification and regression models; Fatty acid composition; Data fusion
Characterisation of PDO olive oil Chianti Classico by non-selective (UV–visible, NIR and MIR spectroscopy) and selective (fatty acid composition) analytical techniques by M. Casale; P. Oliveri; C. Casolino; N. Sinelli; P. Zunin; C. Armanino; M. Forina; S. Lanteri (pp. 56-63).
Display Omitted► Characterisation of the Italian PDO extra virgin olive oil Chianti Classico. ► Comparison between non-selective (UV–vis, NIR and MIR spectroscopy) and selective (fatty acid composition) analytical techniques. ► Synergy among spectroscopic techniques, by the fusion of the respective spectra. ► Prediction of the content of oleic and linoleic acids in the olive oils.An authentication study of the Italian PDO (protected designation of origin) extra virgin olive oil Chianti Classico was performed; UV–visible (UV–vis), Near-Infrared (NIR) and Mid-Infrared (MIR) spectroscopies were applied to a set of samples representative of the whole Chianti Classico production area.The non-selective signals (fingerprints) provided by the three spectroscopic techniques were utilised both individually and jointly, after fusion of the respective profile vectors, in order to build a model for the Chianti Classico PDO olive oil.Moreover, these results were compared with those obtained by the gas chromatographic determination of the fatty acids composition.In order to characterise the olive oils produced in the Chianti Classico PDO area, UNEQ (unequal class models) and SIMCA (soft independent modelling of class analogy) were employed both on the MIR, NIR and UV–vis spectra, individually and jointly, and on the fatty acid composition.Finally, PLS (partial least square) regression was applied on the UV–vis, NIR and MIR spectra, in order to predict the content of oleic and linoleic acids in the extra virgin olive oils.UNEQ, SIMCA and PLS were performed after selection of the relevant predictors, in order to increase the efficiency of both classification and regression models.The non-selective information obtained from UV–vis, NIR and MIR spectroscopy allowed to build reliable models for checking the authenticity of the Italian PDO extra virgin olive oil Chianti Classico.
Keywords: Chianti Classico; PDO olive oil; Spectroscopy; Classification and regression models; Fatty acid composition; Data fusion
Nonenzymatic amperometric organic peroxide sensor based on nano-cobalt phthalocyanine loaded functionalized graphene film by Lin Cui; Lijian Chen; Minrong Xu; Haichao Su; Shiyun Ai (pp. 64-71).
Display Omitted► A sensor fabricated on cobalt phthalocyanine loaded functionalized graphene. ► The sensor can be applied to the tert-butyl hydroperoxide (TBHP) reduction. ► This proposed sensor was designed to detection TBHP in body lotion.An enzyme-free amperometric method was established for the electrochemical reduction tert-butyl hydroperoxide (TBHP) on the utilization of nano-cobalt phthalocyanine (CoPc) loaded functionalized graphene (FGR) and to create a highly responsive organic peroxide sensor. FGR was synthesized with a simple and fast method of electrolysis with potassium hexafluorophosphate (KPF6) solution as electrolyte under the static current of 0.2A. In the present work, FGR was dispersed in the solution of CoPc to fabricate chemical modified electrode to detect TBHP. The electro-reduction of TBHP can be catalyzed by FGR–CoPc, which has an excellent electrocatalytical activity due to the synergistic effect of the FGR with CoPc. The sensor can be applied to the quantification of TBHP with a linear range covering from 0.0260 to 4.81mM, a high sensitivity of 13.64AM−1, and a low detection limit of 5μM. This proposed sensor was designed as a simple, robust, and cheap analytical device for the determination of TBHP in body lotion.
Keywords: Nano-cobalt phthalocyanine (CoPc); Functionalized graphene (FGR); Tert-butyl hydroperoxide (TBHP); Nonenzymatic sensor; Determination
Nonenzymatic amperometric organic peroxide sensor based on nano-cobalt phthalocyanine loaded functionalized graphene film by Lin Cui; Lijian Chen; Minrong Xu; Haichao Su; Shiyun Ai (pp. 64-71).
Display Omitted► A sensor fabricated on cobalt phthalocyanine loaded functionalized graphene. ► The sensor can be applied to the tert-butyl hydroperoxide (TBHP) reduction. ► This proposed sensor was designed to detection TBHP in body lotion.An enzyme-free amperometric method was established for the electrochemical reduction tert-butyl hydroperoxide (TBHP) on the utilization of nano-cobalt phthalocyanine (CoPc) loaded functionalized graphene (FGR) and to create a highly responsive organic peroxide sensor. FGR was synthesized with a simple and fast method of electrolysis with potassium hexafluorophosphate (KPF6) solution as electrolyte under the static current of 0.2A. In the present work, FGR was dispersed in the solution of CoPc to fabricate chemical modified electrode to detect TBHP. The electro-reduction of TBHP can be catalyzed by FGR–CoPc, which has an excellent electrocatalytical activity due to the synergistic effect of the FGR with CoPc. The sensor can be applied to the quantification of TBHP with a linear range covering from 0.0260 to 4.81mM, a high sensitivity of 13.64AM−1, and a low detection limit of 5μM. This proposed sensor was designed as a simple, robust, and cheap analytical device for the determination of TBHP in body lotion.
Keywords: Nano-cobalt phthalocyanine (CoPc); Functionalized graphene (FGR); Tert-butyl hydroperoxide (TBHP); Nonenzymatic sensor; Determination
Determination of chlorophenols in landfill leachate using headspace sampling with ionic liquid-coated solid-phase microextraction fibers combined with gas chromatography–mass spectrometry by Tse-Tsung Ho; Chung-Yu Chen; Zu-Guang Li; Thomas Ching-Cherng Yang; Maw-Rong Lee (pp. 72-77).
Display Omitted► Ionic liquid (IL), ([C4MIM][PF6]), was rapid synthesized by microwave radiation. ► Trace chlorophenols in landfill leachate were extract by SPME coated IL. ► The IL-coated SPME-GC/MS method is low-cost, solvent-free and sensitive.A new microextraction technique based on ionic liquid solid-phase microextraction (IL-SPME) was developed for determination of trace chlorophenols (CPs) in landfill leachate. The synthesized ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate ([C4MIM][PF6]), was coated onto the spent fiber of SPME for extraction of trace CPs. After extraction, the absorbed analytes were desorbed and quantified using gas chromatography–mass spectrometry (GC/MS). The term of the proposed method is as ionic liquid-coated of solid-phase microextraction combined with gas chromatography–mass spectrometry (IL-SPME-GC/MS). No carryover effect was found, and every laboratory-made ionic liquids-coated-fiber could be used for extraction at least eighty times without degradation of efficiency. The chlorophenols studied were 2,4-dichlorophenol (2,4-DP), 2,4,6-trichlorophenol (2,4,6-TCP), 2,3,4,6-tetrachlorophenol (2,3,4,6-TeCP), and pentachlorophenol (PCP). The best results of chlorophenols analysis were obtained with landfill leachate at pH 2, headspace extraction for 4min, and thermal desorption with the gas chromatograph injector at 240°C for 4min. Linearity was observed from 0.1 to 1000μgL−1 with relative standard deviations (RSD) less than 7% and recoveries were over 87%. The limit of detection (LOD) for pentachlorophenol was 0.008μgL−1. The proposed method was tested by analyzing landfill leachate from a sewage farm. The concentrations of chlorophenols were detected to range from 1.1 to 1.4μgL−1. The results demonstrate that the IL-SPME-GC/MS method is highly effective in analyzing trace chlorophenols in landfill leachate.
Keywords: Ionic liquid; Solid-phase microextraction; Chlorophenols; Gas chromatography–mass spectrometry; Landfill leachate
Determination of chlorophenols in landfill leachate using headspace sampling with ionic liquid-coated solid-phase microextraction fibers combined with gas chromatography–mass spectrometry by Tse-Tsung Ho; Chung-Yu Chen; Zu-Guang Li; Thomas Ching-Cherng Yang; Maw-Rong Lee (pp. 72-77).
Display Omitted► Ionic liquid (IL), ([C4MIM][PF6]), was rapid synthesized by microwave radiation. ► Trace chlorophenols in landfill leachate were extract by SPME coated IL. ► The IL-coated SPME-GC/MS method is low-cost, solvent-free and sensitive.A new microextraction technique based on ionic liquid solid-phase microextraction (IL-SPME) was developed for determination of trace chlorophenols (CPs) in landfill leachate. The synthesized ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate ([C4MIM][PF6]), was coated onto the spent fiber of SPME for extraction of trace CPs. After extraction, the absorbed analytes were desorbed and quantified using gas chromatography–mass spectrometry (GC/MS). The term of the proposed method is as ionic liquid-coated of solid-phase microextraction combined with gas chromatography–mass spectrometry (IL-SPME-GC/MS). No carryover effect was found, and every laboratory-made ionic liquids-coated-fiber could be used for extraction at least eighty times without degradation of efficiency. The chlorophenols studied were 2,4-dichlorophenol (2,4-DP), 2,4,6-trichlorophenol (2,4,6-TCP), 2,3,4,6-tetrachlorophenol (2,3,4,6-TeCP), and pentachlorophenol (PCP). The best results of chlorophenols analysis were obtained with landfill leachate at pH 2, headspace extraction for 4min, and thermal desorption with the gas chromatograph injector at 240°C for 4min. Linearity was observed from 0.1 to 1000μgL−1 with relative standard deviations (RSD) less than 7% and recoveries were over 87%. The limit of detection (LOD) for pentachlorophenol was 0.008μgL−1. The proposed method was tested by analyzing landfill leachate from a sewage farm. The concentrations of chlorophenols were detected to range from 1.1 to 1.4μgL−1. The results demonstrate that the IL-SPME-GC/MS method is highly effective in analyzing trace chlorophenols in landfill leachate.
Keywords: Ionic liquid; Solid-phase microextraction; Chlorophenols; Gas chromatography–mass spectrometry; Landfill leachate
Homogeneous ionic liquid microextraction of the active constituents from fruits of Schisandra chinensis and Schisandra sphenanthera by Yao Xiao; Hanqi Zhang (pp. 78-84).
Display Omitted► The ionic liquid was used as extraction solvent and no volatile organic solvent was used. ► The proposed method represents lower expenditures of sample, extraction time and solvent, compared with conventional methods. ► [C4MIM][PF6] was prepared in situ. ► The homogeneous extraction was performed.Homogeneous ionic liquid microextraction (HILME) was developed for the extraction of schizandrin, schisantherin A and deoxyschizandrin from Schisandra chinensis and Schisandra sphenanthera. 1-Butyl-3-methylimidazolium tetrafluoroborate ([C4MIM][BF4]) aqueous solution was used as extraction solvent, and ammonium hexafluorophosphate ([NH4][PF6]) was used as ion-pairing agent. 1-Butyl-3-methylimidazolium hexafluorophosphate ([C4MIM][PF6]), which is barely soluble in water, was formed in situ, and was used as sample solution. High-performance liquid chromatography (HPLC) was employed for separation and determination of the analytes. The calibration curve showed good linear relationship ( r>0.9998). The recoveries were between 69.71% and 88.33% with RSDs lower than 4.86%. External standard method was adopted in the proposed method, and internal standard method was applied for the evaluation of the proposed method. The two methods were compared and the results indicated that the proposed method was acceptable and simple. The HILME is free of volatile organic solvents, and represents lower expenditures of sample, extraction time and solvent, compared with ultrasonic and Soxhlet extraction. There was no obvious difference in the extraction yields of active constitutions obtained by the three extraction methods.
Keywords: Schisandra chinensis; Schisandra sphenanthera; Homogeneous ionic liquid microextraction; High-performance liquid chromatography
Homogeneous ionic liquid microextraction of the active constituents from fruits of Schisandra chinensis and Schisandra sphenanthera by Yao Xiao; Hanqi Zhang (pp. 78-84).
Display Omitted► The ionic liquid was used as extraction solvent and no volatile organic solvent was used. ► The proposed method represents lower expenditures of sample, extraction time and solvent, compared with conventional methods. ► [C4MIM][PF6] was prepared in situ. ► The homogeneous extraction was performed.Homogeneous ionic liquid microextraction (HILME) was developed for the extraction of schizandrin, schisantherin A and deoxyschizandrin from Schisandra chinensis and Schisandra sphenanthera. 1-Butyl-3-methylimidazolium tetrafluoroborate ([C4MIM][BF4]) aqueous solution was used as extraction solvent, and ammonium hexafluorophosphate ([NH4][PF6]) was used as ion-pairing agent. 1-Butyl-3-methylimidazolium hexafluorophosphate ([C4MIM][PF6]), which is barely soluble in water, was formed in situ, and was used as sample solution. High-performance liquid chromatography (HPLC) was employed for separation and determination of the analytes. The calibration curve showed good linear relationship ( r>0.9998). The recoveries were between 69.71% and 88.33% with RSDs lower than 4.86%. External standard method was adopted in the proposed method, and internal standard method was applied for the evaluation of the proposed method. The two methods were compared and the results indicated that the proposed method was acceptable and simple. The HILME is free of volatile organic solvents, and represents lower expenditures of sample, extraction time and solvent, compared with ultrasonic and Soxhlet extraction. There was no obvious difference in the extraction yields of active constitutions obtained by the three extraction methods.
Keywords: Schisandra chinensis; Schisandra sphenanthera; Homogeneous ionic liquid microextraction; High-performance liquid chromatography
Microwave-assisted extraction performed in low temperature and in vacuo for the extraction of labile compounds in food samples by Xiaohua Xiao; Wei Song; Jiayue Wang; Gongke Li (pp. 85-93).
Display Omitted► Low temperature vacuum MAE was studied for the extraction of labile compounds. ► Results of experiments and chemical kinetics were compared and agreed well. ► Both low temperature and in vacuo environment were benefit to the extraction process. ► The method has good potential application in many fields.In this study, low temperature vacuum microwave-assisted extraction, which simultaneous performed microwave-assisted extraction (MAE) in low temperature and in vacuo environment, was proposed. The influencing parameters including solid/liquid ratio, extraction temperature, extraction time, degree of vacuum and microwave power were discussed. The predominance of low temperature vacuum microwave-assisted extraction was investigated by comparing the extraction yields of vitamin C, β-carotene, aloin A and astaxanthin in different foods with that in MAE and solvent extraction, and 5.2–243% increments were obtained. On the other hand, the chemical kinetics of vitamin C and aloin A, which composed two different steps including the extraction step of analyte transferred from matrix into solvent and the decomposition step of analyte degraded in the extraction solvent, were proposed. All of the decomposition rates ( K2) for the selected analyte in low temperature, in vacuo and in nitrogen atmosphere decreased significantly comparing with that in conventional MAE, which are in agreement with that obtained from experiments. Consequently, the present method was successfully applied to extract labile compound from different food samples. These results showed that low temperature and/or in vacuo environment in microwave-assisted extraction system was especially important to prevent the degradation of labile components and have good potential on the extraction of labile compound in foods, pharmaceutical and natural products.
Keywords: Microwave-assisted extraction; Low temperature; In vacuo; Chemical kinetic; Labile compound; Food sample
Microwave-assisted extraction performed in low temperature and in vacuo for the extraction of labile compounds in food samples by Xiaohua Xiao; Wei Song; Jiayue Wang; Gongke Li (pp. 85-93).
Display Omitted► Low temperature vacuum MAE was studied for the extraction of labile compounds. ► Results of experiments and chemical kinetics were compared and agreed well. ► Both low temperature and in vacuo environment were benefit to the extraction process. ► The method has good potential application in many fields.In this study, low temperature vacuum microwave-assisted extraction, which simultaneous performed microwave-assisted extraction (MAE) in low temperature and in vacuo environment, was proposed. The influencing parameters including solid/liquid ratio, extraction temperature, extraction time, degree of vacuum and microwave power were discussed. The predominance of low temperature vacuum microwave-assisted extraction was investigated by comparing the extraction yields of vitamin C, β-carotene, aloin A and astaxanthin in different foods with that in MAE and solvent extraction, and 5.2–243% increments were obtained. On the other hand, the chemical kinetics of vitamin C and aloin A, which composed two different steps including the extraction step of analyte transferred from matrix into solvent and the decomposition step of analyte degraded in the extraction solvent, were proposed. All of the decomposition rates ( K2) for the selected analyte in low temperature, in vacuo and in nitrogen atmosphere decreased significantly comparing with that in conventional MAE, which are in agreement with that obtained from experiments. Consequently, the present method was successfully applied to extract labile compound from different food samples. These results showed that low temperature and/or in vacuo environment in microwave-assisted extraction system was especially important to prevent the degradation of labile components and have good potential on the extraction of labile compound in foods, pharmaceutical and natural products.
Keywords: Microwave-assisted extraction; Low temperature; In vacuo; Chemical kinetic; Labile compound; Food sample
A re-examination of matrix effects in the segmented-flow analysis of nutrients in sea and estuarine water by Stephen Coverly; Roger Kérouel; Alain Aminot (pp. 94-100).
Display Omitted► We reclassify matrix effects and distinguish between static and dynamic origins. ► We contrast matrix effects in debubbled and bubble-through flowcells. ► We show how matrix effects can be measured and reduced. ► We propose simplified correction procedures for chemistry-related matrix effects. ► We propose a semi-automated correction procedure for refractive index blanks.Modern instruments together with the use of standard reference materials have improved the accuracy and long-term reproducibility of the analysis of nutrients (ammonium, nitrate, nitrite, phosphate and silicate) in sea water using segmented-flow analysis, so that errors arising from matrix effects become more significant. Colorimetric detectors with bubble-through flowcells have become widely used for seawater analysis in recent years and their associated matrix effects are described. A re-examination of all categories of matrix effects, whose main origin is salinity, was thus undertaken to assess how much they are liable to alter the data. Interferences were classified into four types, each of which was examined in order to show its influence on the measurements. We discuss how matrix effects can be identified, quantified, reduced and corrected. Chemistry and instrument design play a major role in some matrix effects and recommendations are given to minimise these or make them easier to correct. In particular, the correction for chemical salt effects is revisited for the general case and new, simplified procedures are proposed for its computation. A semi-automated procedure is proposed for measuring and correcting sample and refractive index blanks.
Keywords: Nutrient; Determination; Seawater; Estuarine water; Segmented-flow analysis; Matrix effects
A re-examination of matrix effects in the segmented-flow analysis of nutrients in sea and estuarine water by Stephen Coverly; Roger Kérouel; Alain Aminot (pp. 94-100).
Display Omitted► We reclassify matrix effects and distinguish between static and dynamic origins. ► We contrast matrix effects in debubbled and bubble-through flowcells. ► We show how matrix effects can be measured and reduced. ► We propose simplified correction procedures for chemistry-related matrix effects. ► We propose a semi-automated correction procedure for refractive index blanks.Modern instruments together with the use of standard reference materials have improved the accuracy and long-term reproducibility of the analysis of nutrients (ammonium, nitrate, nitrite, phosphate and silicate) in sea water using segmented-flow analysis, so that errors arising from matrix effects become more significant. Colorimetric detectors with bubble-through flowcells have become widely used for seawater analysis in recent years and their associated matrix effects are described. A re-examination of all categories of matrix effects, whose main origin is salinity, was thus undertaken to assess how much they are liable to alter the data. Interferences were classified into four types, each of which was examined in order to show its influence on the measurements. We discuss how matrix effects can be identified, quantified, reduced and corrected. Chemistry and instrument design play a major role in some matrix effects and recommendations are given to minimise these or make them easier to correct. In particular, the correction for chemical salt effects is revisited for the general case and new, simplified procedures are proposed for its computation. A semi-automated procedure is proposed for measuring and correcting sample and refractive index blanks.
Keywords: Nutrient; Determination; Seawater; Estuarine water; Segmented-flow analysis; Matrix effects
Minimization of side reactions during Lys Tag derivatization of C-terminal lysine peptides by Olav Mjaavatten; Gyrid Nygaard; Frode S. Berven; Frode Selheim (pp. 101-107).
Display Omitted► In this study we found that Lys Tag derivatization of lysine-containing peptides leads to side reactions such as methylation, deamidation and Lys Tag labeling of the N-terminus. ► We found temperature and pH to be the main variables to control side-reactions. ► We show that side-reactions during Lys Tag derivatization can be avoided or minimized by simply lowering the reaction temperature from 55°C to room temperature.Several issues need to be considered concerning chemical labeling strategies in proteomics. Some of these are labeling specificity, possible side reactions, completeness of reaction, recovery rate, conserving integrity of sample, hydrolysis of peptide bonds at high pH, and signal suppression in mass spectrometry (MS). We tested the effects of different reaction conditions for 2-methoxy-4,5-dihydro-1H-imidazole (Lys Tag) derivatization of the ɛ-amine group of lysine ( K) residues. By using nanoflow LC–electrospray ionization-MS (LC–ESI-MS) and MS/MS in combination with MSight 2-D image analysis, we found that standard Lys Tag derivatization processes and conditions induce side reactions such as (i) Lys Tag labeling of the N-terminus, (ii) methylation of internal aspartic acid (D), glutamic acid (E) and C- and N-peptide termini and (iii) deamidation of asparagine (N) and glutamine (Q). We found temperature and pH to be the main variables to control side reactions. Lowering the reaction temperature from 55°C to room temperature reduced deamidation from 22.8±1.4% (SEM) to 7.7±5.5% (SEM) and almost totally blocked methylation (7.0±1.2% (SEM) to 0.4±0.4% (SEM) of the internal acidic amino acids (D and E) at high pH. We conclude that lowering the reaction temperature minimizes undesired side reactions during Lys Tag derivatization in solution.
Keywords: Chromatography; Chemical labeling; Nanoflow LC–ESI-MS; MS/MS; MSight 2-D image analysis
Minimization of side reactions during Lys Tag derivatization of C-terminal lysine peptides by Olav Mjaavatten; Gyrid Nygaard; Frode S. Berven; Frode Selheim (pp. 101-107).
Display Omitted► In this study we found that Lys Tag derivatization of lysine-containing peptides leads to side reactions such as methylation, deamidation and Lys Tag labeling of the N-terminus. ► We found temperature and pH to be the main variables to control side-reactions. ► We show that side-reactions during Lys Tag derivatization can be avoided or minimized by simply lowering the reaction temperature from 55°C to room temperature.Several issues need to be considered concerning chemical labeling strategies in proteomics. Some of these are labeling specificity, possible side reactions, completeness of reaction, recovery rate, conserving integrity of sample, hydrolysis of peptide bonds at high pH, and signal suppression in mass spectrometry (MS). We tested the effects of different reaction conditions for 2-methoxy-4,5-dihydro-1H-imidazole (Lys Tag) derivatization of the ɛ-amine group of lysine ( K) residues. By using nanoflow LC–electrospray ionization-MS (LC–ESI-MS) and MS/MS in combination with MSight 2-D image analysis, we found that standard Lys Tag derivatization processes and conditions induce side reactions such as (i) Lys Tag labeling of the N-terminus, (ii) methylation of internal aspartic acid (D), glutamic acid (E) and C- and N-peptide termini and (iii) deamidation of asparagine (N) and glutamine (Q). We found temperature and pH to be the main variables to control side reactions. Lowering the reaction temperature from 55°C to room temperature reduced deamidation from 22.8±1.4% (SEM) to 7.7±5.5% (SEM) and almost totally blocked methylation (7.0±1.2% (SEM) to 0.4±0.4% (SEM) of the internal acidic amino acids (D and E) at high pH. We conclude that lowering the reaction temperature minimizes undesired side reactions during Lys Tag derivatization in solution.
Keywords: Chromatography; Chemical labeling; Nanoflow LC–ESI-MS; MS/MS; MSight 2-D image analysis
Quantification of vitamin B6 vitamers in human cerebrospinal fluid by ultra performance liquid chromatography–tandem mass spectrometry by M. van der Ham; M. Albersen; T.J. de Koning; G. Visser; A. Middendorp; M. Bosma; N.M. Verhoeven-Duif; M.G.M. de Sain-van der Velden (pp. 108-114).
Display Omitted► We present a sensitive UPLC–MS/MS method for quantification of B6 vitamers in human CSF. ► Our method is very accurate since stable isotope labeled internal standards are used. ► We present data on light sensitivity, temperature dependence and rostrocaudal gradient. ► With PN supplementation, concentrations of PL, PM, PN and PA in CSF are increased. ► Our fully validated method is suitable for implementation in a diagnostic setting.Since vitamin B6 is essential for normal functioning of the central nervous system, there is growing need for sensitive analysis of B6 vitamers in cerebrospinal fluid (CSF). This manuscript describes the development and validation of a rapid, sensitive and accurate method for quantification of the vitamin B6 vitamers pyridoxal (PL), pyridoxamine (PM), pyridoxine (PN), pyridoxic acid (PA), pyridoxal 5′-phosphate (PLP), pyridoxamine 5′-phosphate (PMP) and pyridoxine 5′-phosphate (PNP) in human CSF.The method is based on ultra performance liquid chromatography–tandem mass spectrometry (UPLC–MS/MS) with a simple sample preparation procedure of protein precipitation using 50gL−1 trichloroacetic acid containing stable isotope labeled internal standards: PL-D3 for PL and PM, PN-13C4 for PN, PA-D2 for PA and PLP-D3 for the phosphorylated vitamers. B6 vitamers were separated (Acquity HSS-T3 UPLC column) with a buffer containing acetic acid, heptafluorobutyric acid and acetonitrile. Positive electrospray ionization was used to monitor transitions m/ z 168.1→150.1 (PL), 169.1→134.1 (PM), 170.1→134.1 (PN), 184.1→148.1 (PA), 248.1→150.1 (PLP), 249.1→232.1 (PMP) and 250.1→134.1 (PNP).The method was validated at three concentration levels for each B6 vitamer in CSF. Recoveries of the internal standards were between 93% and 96%. Intra- and inter-assay variations were below 20%. Accuracy tests showed deviations from 3% (PN) to 39% (PMP). Limits of quantification were in the range of 0.03–5.37nM. Poor results were obtained for quantification of PNP.The method was applied to CSF samples of 20 subjects and two patients on pyridoxine supplementation. Using minimal CSF volumes this method is suitable for implementation in a routine diagnostic setting.
Keywords: B6 vitamers; Cerebrospinal fluid; Liquid chromatography; Tandem mass spectrometry
Quantification of vitamin B6 vitamers in human cerebrospinal fluid by ultra performance liquid chromatography–tandem mass spectrometry by M. van der Ham; M. Albersen; T.J. de Koning; G. Visser; A. Middendorp; M. Bosma; N.M. Verhoeven-Duif; M.G.M. de Sain-van der Velden (pp. 108-114).
Display Omitted► We present a sensitive UPLC–MS/MS method for quantification of B6 vitamers in human CSF. ► Our method is very accurate since stable isotope labeled internal standards are used. ► We present data on light sensitivity, temperature dependence and rostrocaudal gradient. ► With PN supplementation, concentrations of PL, PM, PN and PA in CSF are increased. ► Our fully validated method is suitable for implementation in a diagnostic setting.Since vitamin B6 is essential for normal functioning of the central nervous system, there is growing need for sensitive analysis of B6 vitamers in cerebrospinal fluid (CSF). This manuscript describes the development and validation of a rapid, sensitive and accurate method for quantification of the vitamin B6 vitamers pyridoxal (PL), pyridoxamine (PM), pyridoxine (PN), pyridoxic acid (PA), pyridoxal 5′-phosphate (PLP), pyridoxamine 5′-phosphate (PMP) and pyridoxine 5′-phosphate (PNP) in human CSF.The method is based on ultra performance liquid chromatography–tandem mass spectrometry (UPLC–MS/MS) with a simple sample preparation procedure of protein precipitation using 50gL−1 trichloroacetic acid containing stable isotope labeled internal standards: PL-D3 for PL and PM, PN-13C4 for PN, PA-D2 for PA and PLP-D3 for the phosphorylated vitamers. B6 vitamers were separated (Acquity HSS-T3 UPLC column) with a buffer containing acetic acid, heptafluorobutyric acid and acetonitrile. Positive electrospray ionization was used to monitor transitions m/ z 168.1→150.1 (PL), 169.1→134.1 (PM), 170.1→134.1 (PN), 184.1→148.1 (PA), 248.1→150.1 (PLP), 249.1→232.1 (PMP) and 250.1→134.1 (PNP).The method was validated at three concentration levels for each B6 vitamer in CSF. Recoveries of the internal standards were between 93% and 96%. Intra- and inter-assay variations were below 20%. Accuracy tests showed deviations from 3% (PN) to 39% (PMP). Limits of quantification were in the range of 0.03–5.37nM. Poor results were obtained for quantification of PNP.The method was applied to CSF samples of 20 subjects and two patients on pyridoxine supplementation. Using minimal CSF volumes this method is suitable for implementation in a routine diagnostic setting.
Keywords: B6 vitamers; Cerebrospinal fluid; Liquid chromatography; Tandem mass spectrometry
A ratiometric fluorescent chemodosimeter for Cu(II) in water with high selectivity and sensitivity by Kai Li; Na Li; Xiaotong Chen; Aijun Tong (pp. 115-119).
Display Omitted► A coumarin-based ratiometric chemodosimeter for the detection of Cu(II) is facilely synthesized by three steps reactions. ► Cu(II) catalyzes the hydrolysis of chemodosimeter with ratiometric fluorescence signal greatly amplified. ► Detection of Cu(II) can be performed in water at neutral pH with high sensitivity. ► The chemodosimeter exhibits remarkably selective fluorescence enhancement to Cu(II) over other metal ions.Coumarin derivative1 was synthesized as an efficient ratiometric chemodosimeter for the detection of Cu(II) in 99% water/DMSO ( v/ v) at pH 7.0. Mechanism studies suggested that1 formed a complex with Cu(II) at 2:1 ratio accompanied by quenching of green fluorescence at 524nm; when the solution was heated to 50°C for 30min, Cu(II)-promoted hydrolysis of coumarin lactone moiety of1 occurred with bright blue fluorescence at 451nm emerged. With fluorescence intensity ratio detection at 451nm and 524nm,1 features an excellent sensitivity with the detection limit of 15nmolL−1 toward Cu(II) and a good selectivity over other metal ions.
Keywords: Copper ion; Ratiometric fluorescence; Chemodosimeter; Coumarin derivative
A ratiometric fluorescent chemodosimeter for Cu(II) in water with high selectivity and sensitivity by Kai Li; Na Li; Xiaotong Chen; Aijun Tong (pp. 115-119).
Display Omitted► A coumarin-based ratiometric chemodosimeter for the detection of Cu(II) is facilely synthesized by three steps reactions. ► Cu(II) catalyzes the hydrolysis of chemodosimeter with ratiometric fluorescence signal greatly amplified. ► Detection of Cu(II) can be performed in water at neutral pH with high sensitivity. ► The chemodosimeter exhibits remarkably selective fluorescence enhancement to Cu(II) over other metal ions.Coumarin derivative1 was synthesized as an efficient ratiometric chemodosimeter for the detection of Cu(II) in 99% water/DMSO ( v/ v) at pH 7.0. Mechanism studies suggested that1 formed a complex with Cu(II) at 2:1 ratio accompanied by quenching of green fluorescence at 524nm; when the solution was heated to 50°C for 30min, Cu(II)-promoted hydrolysis of coumarin lactone moiety of1 occurred with bright blue fluorescence at 451nm emerged. With fluorescence intensity ratio detection at 451nm and 524nm,1 features an excellent sensitivity with the detection limit of 15nmolL−1 toward Cu(II) and a good selectivity over other metal ions.
Keywords: Copper ion; Ratiometric fluorescence; Chemodosimeter; Coumarin derivative
Mn-doped ZnS quantum dots for the determination of acetone by phosphorescence attenuation by Emma Sotelo-Gonzalez; María T. Fernandez-Argüelles; Jose M. Costa-Fernandez; Alfredo Sanz-Medel (pp. 120-126).
Display Omitted► Colloidal Mn:ZnS QDs exhibiting intense and long-lasting phosphorescence were synthesized and exhaustively characterized. ► Several experimental factors that influence classical phosphorescence do not modify the Mn:ZnS QDs phosphorescence emission. ► Mn:ZnS QDs have been applied for phosphorescence-based acetone determination. ► A mechanism has been proposed to explain acetone quenching effect on QDs phosphorescence.Quantum dot (QD) nanoparticles (NPs) are increasingly used as highly valuable fluorescent biomarkers and as sensitive (bio)chemical probes. Interestingly, if certain metal impurities are incorporated during the NPs synthesis, phosphorescent QDs with analytical potential can be obtained.We report here the synthesis of colloidal manganese-doped ZnS nanoparticles which have been surface-modified withl-cysteine that exhibit an intense room temperature phosphorescence (RTP) emission in aqueous media even in the presence of dissolved oxygen (i.e. sample deoxygenation is not needed). An exhaustive RTP photoluminescent and morphological characterization of the synthesized QDs and their potential for development of phosphorescent analytical methodologies is described. Application to analytical control of acetone (“model analyte” from the ketones family) in water and urine samples is carried out by measuring the QDs phosphorescence quenching rate.The observed results showed a high selectivity of Mn2+-doped ZnS QDs towards acetone. The linear range of the developed methodology turned out to be at least up to 600mgL−1 with a detection limit (DL) for acetone dissolved in aqueous medium of 0.2mgL−1. The developed methodology was finally applied for acetone determination in different spiked water and urine samples, and the recoveries fall in the range of 93–107%.
Keywords: Quantum dots; Phosphorescence; Luminescence; Acetone determination; Nanoparticles
Mn-doped ZnS quantum dots for the determination of acetone by phosphorescence attenuation by Emma Sotelo-Gonzalez; María T. Fernandez-Argüelles; Jose M. Costa-Fernandez; Alfredo Sanz-Medel (pp. 120-126).
Display Omitted► Colloidal Mn:ZnS QDs exhibiting intense and long-lasting phosphorescence were synthesized and exhaustively characterized. ► Several experimental factors that influence classical phosphorescence do not modify the Mn:ZnS QDs phosphorescence emission. ► Mn:ZnS QDs have been applied for phosphorescence-based acetone determination. ► A mechanism has been proposed to explain acetone quenching effect on QDs phosphorescence.Quantum dot (QD) nanoparticles (NPs) are increasingly used as highly valuable fluorescent biomarkers and as sensitive (bio)chemical probes. Interestingly, if certain metal impurities are incorporated during the NPs synthesis, phosphorescent QDs with analytical potential can be obtained.We report here the synthesis of colloidal manganese-doped ZnS nanoparticles which have been surface-modified withl-cysteine that exhibit an intense room temperature phosphorescence (RTP) emission in aqueous media even in the presence of dissolved oxygen (i.e. sample deoxygenation is not needed). An exhaustive RTP photoluminescent and morphological characterization of the synthesized QDs and their potential for development of phosphorescent analytical methodologies is described. Application to analytical control of acetone (“model analyte” from the ketones family) in water and urine samples is carried out by measuring the QDs phosphorescence quenching rate.The observed results showed a high selectivity of Mn2+-doped ZnS QDs towards acetone. The linear range of the developed methodology turned out to be at least up to 600mgL−1 with a detection limit (DL) for acetone dissolved in aqueous medium of 0.2mgL−1. The developed methodology was finally applied for acetone determination in different spiked water and urine samples, and the recoveries fall in the range of 93–107%.
Keywords: Quantum dots; Phosphorescence; Luminescence; Acetone determination; Nanoparticles
An electrochemical aptasensor for chiral peptide detection using layer-by-layer assembly of polyelectrolyte-methylene blue/polyelectrolyte-graphene multilayer by Haixia Qin; Jiyang Liu; Chaogui Chen; JiaHai Wang; Erkang Wang (pp. 127-131).
Display Omitted► An electrochemical aptasensor for selective detection of peptide is constructed. ► This aptasensor is based on grapheme multilayer via layer-by-layer assembly. ► Such multilayer facilitates electron transfer and provides more adsorption sites.Here we demonstrate for the first time that by physically adsorbing aptamer onto conductive film assembled via alternate adsorption of graphene/polyelectrolyte and methylene blue/polyelectrolyte, a label-free electrochemical aptasensor with high sensitivity and selectivity for peptide detection is constructed. Graphene multilayer derived from layer-by-layer assembly has played significant roles in this sensing strategy: allowing accumulation of methylene blue, facilitating electron transfer and providing much more adsorption site. As compared to previous electrochemical aptasensors, the current sensor based on graphene multilayer alternated with electroactive molecule layer offers extremely high capability for sensitive detection of target without interference of environmental surrounding. This electroactive probe-confined graphene multilayer confers great flexibility to combine with differential pulse voltammetry (DPV) together. In the presence of targetd entiomer of arginine vasopressin (d-VP), the binding of peptide to aptamer block the electron transfer process of MB, leading to decreased current peak of DPV. By this way, this electrochemical aptasensor based on electroactive molecule-intercalated graphene multilayer provide highly sensitive and specific detection ofd-VP with the lowest detectable concentration of 1ngmL−1 and a wide detection range from 1 to 265ngmL−1.
Keywords: Layer-by-layer; Graphene; Electrochemical aptasensor; Chiral peptide; Aptamer
An electrochemical aptasensor for chiral peptide detection using layer-by-layer assembly of polyelectrolyte-methylene blue/polyelectrolyte-graphene multilayer by Haixia Qin; Jiyang Liu; Chaogui Chen; JiaHai Wang; Erkang Wang (pp. 127-131).
Display Omitted► An electrochemical aptasensor for selective detection of peptide is constructed. ► This aptasensor is based on grapheme multilayer via layer-by-layer assembly. ► Such multilayer facilitates electron transfer and provides more adsorption sites.Here we demonstrate for the first time that by physically adsorbing aptamer onto conductive film assembled via alternate adsorption of graphene/polyelectrolyte and methylene blue/polyelectrolyte, a label-free electrochemical aptasensor with high sensitivity and selectivity for peptide detection is constructed. Graphene multilayer derived from layer-by-layer assembly has played significant roles in this sensing strategy: allowing accumulation of methylene blue, facilitating electron transfer and providing much more adsorption site. As compared to previous electrochemical aptasensors, the current sensor based on graphene multilayer alternated with electroactive molecule layer offers extremely high capability for sensitive detection of target without interference of environmental surrounding. This electroactive probe-confined graphene multilayer confers great flexibility to combine with differential pulse voltammetry (DPV) together. In the presence of targetd entiomer of arginine vasopressin (d-VP), the binding of peptide to aptamer block the electron transfer process of MB, leading to decreased current peak of DPV. By this way, this electrochemical aptasensor based on electroactive molecule-intercalated graphene multilayer provide highly sensitive and specific detection ofd-VP with the lowest detectable concentration of 1ngmL−1 and a wide detection range from 1 to 265ngmL−1.
Keywords: Layer-by-layer; Graphene; Electrochemical aptasensor; Chiral peptide; Aptamer
Kappa-casein based electrochemical and surface plasmon resonance biosensors for the assessment of the clotting activity of rennet by Maria A. Panagopoulou; Dimitrios V. Stergiou; Ioannis G. Roussis; George Panayotou; Mamas I. Prodromidis (pp. 132-137).
Display Omitted► κ-CN-based electrochemical and SPR biosensors for the clotting power of rennet are described. ► The proposed biosensors were successfully tested at various commercial rennet samples. ► EIS is more reliable and reproducible than DPV.We report for the first time the development of kappa-casein ( κ-CN)-based electrochemical and surface plasmon resonance (SPR) biosensors for the assessment of the clotting activity of rennet. Electrochemical biosensors were developed over gold electrodes modified with a self-assembled monolayer of dithiobis- N-succinimidyl propionate, while SPR measurements were performed on regenerated carboxymethylated dextran gold surfaces. In both types of biosensor, κ-CN molecules were immobilized onto modified gold surfaces through covalent bonding. In electrochemical biosensors, interactions between the immobilized κ-CN molecules and chymosin (the active component of rennet) were studied by performing cyclic voltammetry, differential pulsed voltammetry, and electrochemical impedance spectroscopy (EIS) measurements, using hexacyanoferrate(II)/(III) couple as a redox probe. κ-CN is cleaved by rennet at the Phe105–Met106 bond, producing a soluble glycomacropeptide, which is released to the electrolyte, and the positively charged insoluble para- κ-casein molecule, which remains attached to the surface of the electrode. This induced reduction of the net negative charge of the sensing surface, along with the partial degradation of the sensing layer, results in an increase of the flux of the redox probe, which exists in the solution, and consequently, to signal variations, which are associated with the increased electrocatalysis of the hexacyanoferrate(II)/(III) couple on the gold surface. SPR experiments were performed in the absence of the redox probe and the observed SPR angle alterations were solely attributed to the cleavage of the immobilized κ-CN molecules. Various experimental variables were investigated and under the selected conditions the proposed biosensors were successfully tried to real samples. The ratios of the clotting power units in various commercial solid or liquid samples, as they are calculated by the EIS-based data, were almost identical to those obtained with a reference method. In addition, EIS measurements showed an excellent reproducibility, lower than 5%.
Keywords: Impedimetric biosensors; Rennet; Food analysis; Kappa; -casein; Milk coagulation; Surface plasmon resonance
Kappa-casein based electrochemical and surface plasmon resonance biosensors for the assessment of the clotting activity of rennet by Maria A. Panagopoulou; Dimitrios V. Stergiou; Ioannis G. Roussis; George Panayotou; Mamas I. Prodromidis (pp. 132-137).
Display Omitted► κ-CN-based electrochemical and SPR biosensors for the clotting power of rennet are described. ► The proposed biosensors were successfully tested at various commercial rennet samples. ► EIS is more reliable and reproducible than DPV.We report for the first time the development of kappa-casein ( κ-CN)-based electrochemical and surface plasmon resonance (SPR) biosensors for the assessment of the clotting activity of rennet. Electrochemical biosensors were developed over gold electrodes modified with a self-assembled monolayer of dithiobis- N-succinimidyl propionate, while SPR measurements were performed on regenerated carboxymethylated dextran gold surfaces. In both types of biosensor, κ-CN molecules were immobilized onto modified gold surfaces through covalent bonding. In electrochemical biosensors, interactions between the immobilized κ-CN molecules and chymosin (the active component of rennet) were studied by performing cyclic voltammetry, differential pulsed voltammetry, and electrochemical impedance spectroscopy (EIS) measurements, using hexacyanoferrate(II)/(III) couple as a redox probe. κ-CN is cleaved by rennet at the Phe105–Met106 bond, producing a soluble glycomacropeptide, which is released to the electrolyte, and the positively charged insoluble para- κ-casein molecule, which remains attached to the surface of the electrode. This induced reduction of the net negative charge of the sensing surface, along with the partial degradation of the sensing layer, results in an increase of the flux of the redox probe, which exists in the solution, and consequently, to signal variations, which are associated with the increased electrocatalysis of the hexacyanoferrate(II)/(III) couple on the gold surface. SPR experiments were performed in the absence of the redox probe and the observed SPR angle alterations were solely attributed to the cleavage of the immobilized κ-CN molecules. Various experimental variables were investigated and under the selected conditions the proposed biosensors were successfully tried to real samples. The ratios of the clotting power units in various commercial solid or liquid samples, as they are calculated by the EIS-based data, were almost identical to those obtained with a reference method. In addition, EIS measurements showed an excellent reproducibility, lower than 5%.
Keywords: Impedimetric biosensors; Rennet; Food analysis; Kappa; -casein; Milk coagulation; Surface plasmon resonance
Development of surface chemistry for surface plasmon resonance based sensors for the detection of proteins and DNA molecules by Zeynep Altintas; Yıldız Uludag; Yasar Gurbuz; Ibtisam Tothill (pp. 138-144).
The principle of applied protein and DNA assays on dendrimer modified MUDA-SAM.Display Omitted► Immobilisation of biomolecules to sensor surface is a crucial step for biosensors. ► DNA and protein immobilisation capacities of different sensor surfaces were compared. ► Higher SPR response was obtained for protein immobilisation on dendrimer surfaces.The immobilisation of biological recognition elements onto a sensor chip surface is a crucial step for the construction of biosensors. While some of the optical biosensors utilise silicon dioxide as the sensor surface, most of the biosensor surfaces are coated with metals for transduction of the signal. Biological recognition elements such as proteins can be adsorbed spontaneously on metal or silicon dioxide substrates but this may denature the molecule and can result in either activity reduction or loss. Self assembled monolayers (SAMs) provide an effective method to protect the biological recognition elements from the sensor surface, thereby providing ligand immobilisation that enables the repeated binding and regeneration cycles to be performed without losing the immobilised ligand, as well as additionally helping to minimise non-specific adsorption. Therefore, in this study different surface chemistries were constructed on SPR sensor chips to investigate protein and DNA immobilisation on Au surfaces. A cysteamine surface and 1%, 10% and 100% mercaptoundecanoic acid (MUDA) coatings with or without dendrimer modification were utilised to construct the various sensor surfaces used in this investigation. A higher response was obtained for NeutrAvidin immobilisation on dendrimer modified surfaces compared to MUDA and cysteamine layers, however, protein or DNA capture responses on the immobilised NeutrAvidin did not show a similar higher response when dendrimer modified surfaces were used.
Keywords: Biosensor; Surface chemistry; Surface plasmon resonance; Dendrimer; Mercaptoundecanoic acid
Development of surface chemistry for surface plasmon resonance based sensors for the detection of proteins and DNA molecules by Zeynep Altintas; Yıldız Uludag; Yasar Gurbuz; Ibtisam Tothill (pp. 138-144).
The principle of applied protein and DNA assays on dendrimer modified MUDA-SAM.Display Omitted► Immobilisation of biomolecules to sensor surface is a crucial step for biosensors. ► DNA and protein immobilisation capacities of different sensor surfaces were compared. ► Higher SPR response was obtained for protein immobilisation on dendrimer surfaces.The immobilisation of biological recognition elements onto a sensor chip surface is a crucial step for the construction of biosensors. While some of the optical biosensors utilise silicon dioxide as the sensor surface, most of the biosensor surfaces are coated with metals for transduction of the signal. Biological recognition elements such as proteins can be adsorbed spontaneously on metal or silicon dioxide substrates but this may denature the molecule and can result in either activity reduction or loss. Self assembled monolayers (SAMs) provide an effective method to protect the biological recognition elements from the sensor surface, thereby providing ligand immobilisation that enables the repeated binding and regeneration cycles to be performed without losing the immobilised ligand, as well as additionally helping to minimise non-specific adsorption. Therefore, in this study different surface chemistries were constructed on SPR sensor chips to investigate protein and DNA immobilisation on Au surfaces. A cysteamine surface and 1%, 10% and 100% mercaptoundecanoic acid (MUDA) coatings with or without dendrimer modification were utilised to construct the various sensor surfaces used in this investigation. A higher response was obtained for NeutrAvidin immobilisation on dendrimer modified surfaces compared to MUDA and cysteamine layers, however, protein or DNA capture responses on the immobilised NeutrAvidin did not show a similar higher response when dendrimer modified surfaces were used.
Keywords: Biosensor; Surface chemistry; Surface plasmon resonance; Dendrimer; Mercaptoundecanoic acid
Simultaneous analysis and retention behavior of major isoflavonoids in Radix Puerariae lobatae and Radix Puerariae thomsonii by high performance liquid chromatography with cyclodextrins as a mobile phase modifier by Aiguo Zeng; Jianfeng Xing; Changhe Wang; Jie Song; Cong Li; Xin Yang; Guangde Yang (pp. 145-151).
Typical HPLC chromatograms of a standard mixture of four isoflavonoids (A), Radix Puerariae lobatae (B) and Radix Puerariae thomsonii (C) by HPLC with isocratic elution employing HP-β-CD as mobile phase additives.Display Omitted► The HPLC method with isocratic elution is developed for determination of four isoflavones in P. lobatae and P. thomsonii. ► As a mobile phase additive, HP-β-CD markedly reduces the retention of isoflavonoids. ► The reduction of the isoflavonoid retention is attributed to the formation of the isoflavonoids–HP-β-CD inclusion complexes. ► The retention behavior of isoflavonoids depends on the nature and concentration of CDs and the property of isoflavonoids.In order to differentiate two species of Radix Puerariae ( Radix Puerariae lobatae and Radix Puerariae thomsonii) and to determine major isoflavonoids (puerarin, daidzin, daidzein and genistein) in the samples, a simple high performance liquid chromatography (HPLC) method with isocratic elution employing cyclodextrins (CDs) as mobile phase additives was developed. Various factors affecting the retention of isoflavonoids in the C18 reversed-phase column, such as the nature of CDs, the concentration of hydroxypropyl-β-cyclodextrin (HP-β-CD) and the methanol percentage in the mobile phase, were studied. Experimental results confirmed that HP-β-CD, as a very effective mobile phase additive, could markedly reduce the retention of isoflavonoids, especially daidzein and genistein. The elution of four isoflavonoids could be achieved on a Kromasil® C18 column within 56min by using the methanol–water contained 5mM HP-β-CD (25/75, v/v) mixture as the mobile phase. The formation of the inclusion complexes between isoflavonoids and HP-β-CD explained the modification of the retention of analytes. The apparent formation constants determined by HPLC confirmed that the stoichiometry of HP-β-CD-isoflavonoid complexes was 1:1, and the stability of the complexes depended on the size and property of isoflavonoids. The optimized method was successfully applied for the simultaneous determination of major isoflavonoids in P. lobatae and P. thomsonii samples. This work provides a useful method for the analysis of traditional Chinese herbs.
Keywords: Isoflavonoids; Cyclodextrins; Isocratic elution; Inclusion complexes; Radix Puerariae lobatae; Radix Puerariae thomsonii
Simultaneous analysis and retention behavior of major isoflavonoids in Radix Puerariae lobatae and Radix Puerariae thomsonii by high performance liquid chromatography with cyclodextrins as a mobile phase modifier by Aiguo Zeng; Jianfeng Xing; Changhe Wang; Jie Song; Cong Li; Xin Yang; Guangde Yang (pp. 145-151).
Typical HPLC chromatograms of a standard mixture of four isoflavonoids (A), Radix Puerariae lobatae (B) and Radix Puerariae thomsonii (C) by HPLC with isocratic elution employing HP-β-CD as mobile phase additives.Display Omitted► The HPLC method with isocratic elution is developed for determination of four isoflavones in P. lobatae and P. thomsonii. ► As a mobile phase additive, HP-β-CD markedly reduces the retention of isoflavonoids. ► The reduction of the isoflavonoid retention is attributed to the formation of the isoflavonoids–HP-β-CD inclusion complexes. ► The retention behavior of isoflavonoids depends on the nature and concentration of CDs and the property of isoflavonoids.In order to differentiate two species of Radix Puerariae ( Radix Puerariae lobatae and Radix Puerariae thomsonii) and to determine major isoflavonoids (puerarin, daidzin, daidzein and genistein) in the samples, a simple high performance liquid chromatography (HPLC) method with isocratic elution employing cyclodextrins (CDs) as mobile phase additives was developed. Various factors affecting the retention of isoflavonoids in the C18 reversed-phase column, such as the nature of CDs, the concentration of hydroxypropyl-β-cyclodextrin (HP-β-CD) and the methanol percentage in the mobile phase, were studied. Experimental results confirmed that HP-β-CD, as a very effective mobile phase additive, could markedly reduce the retention of isoflavonoids, especially daidzein and genistein. The elution of four isoflavonoids could be achieved on a Kromasil® C18 column within 56min by using the methanol–water contained 5mM HP-β-CD (25/75, v/v) mixture as the mobile phase. The formation of the inclusion complexes between isoflavonoids and HP-β-CD explained the modification of the retention of analytes. The apparent formation constants determined by HPLC confirmed that the stoichiometry of HP-β-CD-isoflavonoid complexes was 1:1, and the stability of the complexes depended on the size and property of isoflavonoids. The optimized method was successfully applied for the simultaneous determination of major isoflavonoids in P. lobatae and P. thomsonii samples. This work provides a useful method for the analysis of traditional Chinese herbs.
Keywords: Isoflavonoids; Cyclodextrins; Isocratic elution; Inclusion complexes; Radix Puerariae lobatae; Radix Puerariae thomsonii
Functional gigaporous polystyrene microspheres facilitating separation of poly(ethylene glycol)–protein conjugate by Yanqin Zhai; Weiqing Zhou; Wei Wei; Jianbo Qu; Jiandu Lei; Zhiguo Su; Guanghui Ma (pp. 152-161).
A novel sulfopropyl gigaporous polystyrene (SP-GP) microsphere enhancing the separation of PEGylated protein was first presented. The SP-GP microspheres were successfully prepared by introducing sulfopropyl groups into agarose-coated gigaporous polystyrene microspheres and used as chromatography media. Compared with a commercial medium, SP-GP microspheres exhibited improved column efficiency and reduced backpressure with increasing flow velocity, which could ensure its use in high-speed chromatography. Furthermore, a higher protein recovery and purity of the PEGylated protein could be obtained, even when SP-GP was applied at a flow velocity of 1224cmh−1. Additionally, the dynamic binding capacity (DBC) of P-GP was significantly improved, which was higher than 10mgmL−1 medium even at a flow velocity of 306cmh−1. Further investigation using a laser scanning confocal microscope (LSCM) demonstrated that the static adsorption equilibrium of the PEGylated protein on SP-GP could be completed in 5min, whereas a much longer period (ca. 60min) was required for the commercial medium, indicating that the mass transfer of SP-GP was much faster with the gigaporous structure. All of these results strongly support that our developed SP-GP could serve as a promising cation exchange chromatography resin for high-speed separation, especially for biomolecules of high molecular weight.▪.► We prepared a functional gigaporous microsphere enhancing PEG–protein separation. ► We demonstrated column efficiency of the microspheres in high-speed chromatography. ► We investigated mass transfer behavior of PEG–protein into the microspheres.A novel sulfopropyl gigaporous polystyrene (SP-GP) microsphere enhancing the separation of poly(ethylene glycol)–protein (PEGylated protein) was first presented. The SP-GP microspheres were successfully prepared by introducing sulfopropyl groups into agarose-coated gigaporous polystyrene microspheres and used as chromatography media. Compared with a commercial medium, SP-GP microspheres exhibited improved column efficiency and reduced backpressure with increasing flow velocity, which could ensure its use in high-speed chromatography. Furthermore, a higher protein recovery and purity of the PEGylated protein could be obtained, even when SP-GP was applied at a flow velocity of 1224cmh−1. Additionally, the dynamic binding capacity (DBC) of SP-GP was significantly improved, which was higher than 10mgmL−1 medium even at a flow velocity of 306cmh−1. Further investigation using a laser scanning confocal microscope (LSCM) demonstrated that the static adsorption equilibrium of the PEGylated protein on SP-GP could be completed in 5min, whereas a much longer period (ca. 60min) was required for the commercial medium, indicating that the mass transfer of SP-GP was much faster with the gigaporous structure. All of these results strongly support that our developed SP-GP could serve as a promising cation exchange chromatography resin for high-speed separation, especially for biomolecules of high molecular weight.
Keywords: Gigaporous; Polystyrene microspheres; Poly(ethylene glycol)–protein; Chromatography media
Functional gigaporous polystyrene microspheres facilitating separation of poly(ethylene glycol)–protein conjugate by Yanqin Zhai; Weiqing Zhou; Wei Wei; Jianbo Qu; Jiandu Lei; Zhiguo Su; Guanghui Ma (pp. 152-161).
A novel sulfopropyl gigaporous polystyrene (SP-GP) microsphere enhancing the separation of PEGylated protein was first presented. The SP-GP microspheres were successfully prepared by introducing sulfopropyl groups into agarose-coated gigaporous polystyrene microspheres and used as chromatography media. Compared with a commercial medium, SP-GP microspheres exhibited improved column efficiency and reduced backpressure with increasing flow velocity, which could ensure its use in high-speed chromatography. Furthermore, a higher protein recovery and purity of the PEGylated protein could be obtained, even when SP-GP was applied at a flow velocity of 1224cmh−1. Additionally, the dynamic binding capacity (DBC) of P-GP was significantly improved, which was higher than 10mgmL−1 medium even at a flow velocity of 306cmh−1. Further investigation using a laser scanning confocal microscope (LSCM) demonstrated that the static adsorption equilibrium of the PEGylated protein on SP-GP could be completed in 5min, whereas a much longer period (ca. 60min) was required for the commercial medium, indicating that the mass transfer of SP-GP was much faster with the gigaporous structure. All of these results strongly support that our developed SP-GP could serve as a promising cation exchange chromatography resin for high-speed separation, especially for biomolecules of high molecular weight.▪.► We prepared a functional gigaporous microsphere enhancing PEG–protein separation. ► We demonstrated column efficiency of the microspheres in high-speed chromatography. ► We investigated mass transfer behavior of PEG–protein into the microspheres.A novel sulfopropyl gigaporous polystyrene (SP-GP) microsphere enhancing the separation of poly(ethylene glycol)–protein (PEGylated protein) was first presented. The SP-GP microspheres were successfully prepared by introducing sulfopropyl groups into agarose-coated gigaporous polystyrene microspheres and used as chromatography media. Compared with a commercial medium, SP-GP microspheres exhibited improved column efficiency and reduced backpressure with increasing flow velocity, which could ensure its use in high-speed chromatography. Furthermore, a higher protein recovery and purity of the PEGylated protein could be obtained, even when SP-GP was applied at a flow velocity of 1224cmh−1. Additionally, the dynamic binding capacity (DBC) of SP-GP was significantly improved, which was higher than 10mgmL−1 medium even at a flow velocity of 306cmh−1. Further investigation using a laser scanning confocal microscope (LSCM) demonstrated that the static adsorption equilibrium of the PEGylated protein on SP-GP could be completed in 5min, whereas a much longer period (ca. 60min) was required for the commercial medium, indicating that the mass transfer of SP-GP was much faster with the gigaporous structure. All of these results strongly support that our developed SP-GP could serve as a promising cation exchange chromatography resin for high-speed separation, especially for biomolecules of high molecular weight.
Keywords: Gigaporous; Polystyrene microspheres; Poly(ethylene glycol)–protein; Chromatography media
Comparison of storage stability of odorous VOCs in polyester aluminum and polyvinyl fluoride Tedlar® bags by Yong-Hyun Kim; Ki-Hyun Kim; Sang-Hee Jo; Eui-Chan Jeon; Jong Ryeul Sohn; David B. Parker (pp. 162-167).
Chromatogram of P-1 sample (refer to Table 2): analysis made after loading 50mL (50mLmin−1×1min) of 100ppb VOC standard.Display Omitted► A shortage of polyvinyl fluoride (PVF) Tedlar bags has been projected. ► Alternative sampling bags that can replace PVF are in great demand. ► The relative performance of polyester aluminum bags (PEA) and PVF is compared for VOC sampling. ► The results will help scientists learn the fundamental aspects of bag sampling techniques.Whole air sampling using containers such as flexible bags or rigid canisters is commonly used to collect samples of volatile organic compounds (VOC) in air. The objective of this study was to compare the stability of polyester aluminum (PEA) and polyvinyl fluoride (PVF, brand name Tedlar®) bags for gaseous VOC sampling. Eight VOC standards (benzene, toluene, p-xylene, styrene, methyl ethyl ketone, methyl isobutyl ketone, butyl acetate, and isobutyl alcohol) were placed into each bag at storage times of 0, 2, and 3 days prior to analyses by gas chromatography/mass spectrometry (GC/MS). From each bag representing each storage day, samples of 3 different mass loadings were withdrawn and analyzed to derive response factors (RF) of each chemical between the slope of the GC response ( y-axis) vs. loaded mass ( x-axis). The relative recoveries (RR) of VOC, if derived by dividing RF value of a given storage day by that of 0 day, varied by time, bag type, and VOC type. If the RR values after three days are compared, those of methyl isobutyl ketone were the highest with 96 (PVF) and 99% (PEA); however, the results of isobutyl alcohol were highly contrasting between the two bags with 31 and 94%, respectively. Differences in RR values between the two bag types increased with storage time, such that RR of PEA bags (88±10%) were superior to those of PVF bags (73±22%) after three days, demonstrating that VOC in PEA bags were more stable than in PVF bags.
Keywords: Tedlar bag (PVF); Polyester bag (PEA); Relative recovery; Storage time; Sorptive loss
Comparison of storage stability of odorous VOCs in polyester aluminum and polyvinyl fluoride Tedlar® bags by Yong-Hyun Kim; Ki-Hyun Kim; Sang-Hee Jo; Eui-Chan Jeon; Jong Ryeul Sohn; David B. Parker (pp. 162-167).
Chromatogram of P-1 sample (refer to Table 2): analysis made after loading 50mL (50mLmin−1×1min) of 100ppb VOC standard.Display Omitted► A shortage of polyvinyl fluoride (PVF) Tedlar bags has been projected. ► Alternative sampling bags that can replace PVF are in great demand. ► The relative performance of polyester aluminum bags (PEA) and PVF is compared for VOC sampling. ► The results will help scientists learn the fundamental aspects of bag sampling techniques.Whole air sampling using containers such as flexible bags or rigid canisters is commonly used to collect samples of volatile organic compounds (VOC) in air. The objective of this study was to compare the stability of polyester aluminum (PEA) and polyvinyl fluoride (PVF, brand name Tedlar®) bags for gaseous VOC sampling. Eight VOC standards (benzene, toluene, p-xylene, styrene, methyl ethyl ketone, methyl isobutyl ketone, butyl acetate, and isobutyl alcohol) were placed into each bag at storage times of 0, 2, and 3 days prior to analyses by gas chromatography/mass spectrometry (GC/MS). From each bag representing each storage day, samples of 3 different mass loadings were withdrawn and analyzed to derive response factors (RF) of each chemical between the slope of the GC response ( y-axis) vs. loaded mass ( x-axis). The relative recoveries (RR) of VOC, if derived by dividing RF value of a given storage day by that of 0 day, varied by time, bag type, and VOC type. If the RR values after three days are compared, those of methyl isobutyl ketone were the highest with 96 (PVF) and 99% (PEA); however, the results of isobutyl alcohol were highly contrasting between the two bags with 31 and 94%, respectively. Differences in RR values between the two bag types increased with storage time, such that RR of PEA bags (88±10%) were superior to those of PVF bags (73±22%) after three days, demonstrating that VOC in PEA bags were more stable than in PVF bags.
Keywords: Tedlar bag (PVF); Polyester bag (PEA); Relative recovery; Storage time; Sorptive loss