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Analytica Chimica Acta (v.683, #2)
Evaluation of photodynamic therapy (PDT) procedures using microfluidic system by Elzbieta Jedrych; Zuzanna Pawlicka; Michal Chudy; Artur Dybko; Zbigniew Brzozka (pp. 149-155).
A hybrid PDMS/glass microfluidic system for evaluation of the efficiency of photodynamic therapy is presented. 5-aminolevulinic acid (ALA) was used as a precursor of photosensitizer. The geometry of the microdevice presented in this paper enables to test different concentrations of the photosensitizer in a single assay. The viability of the A549 cells was determined 24h after PDT procedure (irradiation with light which induced a photosensitizer accumulated in carcinoma cells, λ=625nm). The presented results confirmed the possibility to perform the photodynamic therapy process in vitro in microscale and the possibility to assess its effectiveness. Moreover, because two identical microstructures on a single chip were performed, the microchip can be used for examination simultaneously various cell lines (carcinoma and normal) or various photosensitizers.
Keywords: Photodynamic therapy (PDT); Microfluidic system; Lab on a chip; Cancer treatment; Cell culture
Evaluation of photodynamic therapy (PDT) procedures using microfluidic system by Elzbieta Jedrych; Zuzanna Pawlicka; Michal Chudy; Artur Dybko; Zbigniew Brzozka (pp. 149-155).
A hybrid PDMS/glass microfluidic system for evaluation of the efficiency of photodynamic therapy is presented. 5-aminolevulinic acid (ALA) was used as a precursor of photosensitizer. The geometry of the microdevice presented in this paper enables to test different concentrations of the photosensitizer in a single assay. The viability of the A549 cells was determined 24h after PDT procedure (irradiation with light which induced a photosensitizer accumulated in carcinoma cells, λ=625nm). The presented results confirmed the possibility to perform the photodynamic therapy process in vitro in microscale and the possibility to assess its effectiveness. Moreover, because two identical microstructures on a single chip were performed, the microchip can be used for examination simultaneously various cell lines (carcinoma and normal) or various photosensitizers.
Keywords: Photodynamic therapy (PDT); Microfluidic system; Lab on a chip; Cancer treatment; Cell culture
Synthetic membranes (vesicles) in inorganic ion analysis: A review by Dimosthenis L. Giokas; Athanasios G. Vlessidis (pp. 156-169).
Vesicles are structures of amphiphile molecules occurring through a self-aggregation process at the molecular or nano scale level with a large structural variety and diverse properties providing a reaction environment for chemical reactions that resembles that of natural systems. Their high versatility and recognized utility in various applications have triggered a interdisciplinary scientific endeavor over their formation, characterization and potential applications with impressive results. However, in the vastness of applications surrounding vesicular structures, their utility in analytical chemistry has only received minor attention. Notwithstanding, studies demonstrating their potential as colorimetric or fluorescence sensors, extraction solvents of inorganic ions or their chelates and stationary phase modifiers in liquid chromatography have appeared. To this end, this article aims to present for the first time the analytical chemistry aspects behind the use of vesicle media with special emphasis on the detection and determination of inorganic ions and encourage further research on this promising field of analytical science.
Keywords: Synthetic membranes; Vesicles; Inorganic ions; Review
Synthetic membranes (vesicles) in inorganic ion analysis: A review by Dimosthenis L. Giokas; Athanasios G. Vlessidis (pp. 156-169).
Vesicles are structures of amphiphile molecules occurring through a self-aggregation process at the molecular or nano scale level with a large structural variety and diverse properties providing a reaction environment for chemical reactions that resembles that of natural systems. Their high versatility and recognized utility in various applications have triggered a interdisciplinary scientific endeavor over their formation, characterization and potential applications with impressive results. However, in the vastness of applications surrounding vesicular structures, their utility in analytical chemistry has only received minor attention. Notwithstanding, studies demonstrating their potential as colorimetric or fluorescence sensors, extraction solvents of inorganic ions or their chelates and stationary phase modifiers in liquid chromatography have appeared. To this end, this article aims to present for the first time the analytical chemistry aspects behind the use of vesicle media with special emphasis on the detection and determination of inorganic ions and encourage further research on this promising field of analytical science.
Keywords: Synthetic membranes; Vesicles; Inorganic ions; Review
Analysis of time-dependent conjugation of gold nanoparticles with an antiparkinsonian molecule by using curve resolution methods by José Manuel Amigo; Neus G. Bastús; Rob Hoen; Socorro Vázquez-Campos; Miriam Varón; Miriam Royo; Victor Puntes (pp. 170-177).
In this work, the time-dependent conjugation process between a thiolated molecule (with anti-parkinsonian properties) and gold nanoparticles has been monitored and studied by the combined use of fast acquisition Ultra Violet–Visible (UV–Vis) spectra and the ability of Multivariate Curve Resolution-Alternating Least Squares (MCR-ALS) technique. From the highly informative kinetic profiles obtained it was possible to extract quantitative and qualitative information of the conjugation process which includes i) time-dependent concentration profiles and pure spectra of species involved on conjugation process, ii) estimation of molecule concentration necessary for the completeness of the conjugation reaction, iii) molecule footprint and iv) free energy of molecule adsorption.
Keywords: Gold nanoparticles; Adenosine antagonist; Multivariate Curve Resolution-Alternating Least Squares; Ultra Violet–Visible spectroscopy; Kinetic modeling
Analysis of time-dependent conjugation of gold nanoparticles with an antiparkinsonian molecule by using curve resolution methods by José Manuel Amigo; Neus G. Bastús; Rob Hoen; Socorro Vázquez-Campos; Miriam Varón; Miriam Royo; Victor Puntes (pp. 170-177).
In this work, the time-dependent conjugation process between a thiolated molecule (with anti-parkinsonian properties) and gold nanoparticles has been monitored and studied by the combined use of fast acquisition Ultra Violet–Visible (UV–Vis) spectra and the ability of Multivariate Curve Resolution-Alternating Least Squares (MCR-ALS) technique. From the highly informative kinetic profiles obtained it was possible to extract quantitative and qualitative information of the conjugation process which includes i) time-dependent concentration profiles and pure spectra of species involved on conjugation process, ii) estimation of molecule concentration necessary for the completeness of the conjugation reaction, iii) molecule footprint and iv) free energy of molecule adsorption.
Keywords: Gold nanoparticles; Adenosine antagonist; Multivariate Curve Resolution-Alternating Least Squares; Ultra Violet–Visible spectroscopy; Kinetic modeling
Spectrophotometric study of complex formation equilibria in the presence of interference using hard–soft net analyte signal method: Application to drug–metal complexation by Bahram Hemmateenejad; Mohsen Nekoeinia; Ghodratollah Absalan (pp. 178-186).
In this article, the ability of a new and efficient hard–soft method, previously proposed by our research group, is reported for modeling of the complex formation equilibria in the presence of interferences. This method is based on the net analyte signal (NAS) concept, which is a part of total signal that is directly related to the concentration of the component of interest. It monitors the concentration changes of any chemical species involved in the evolutionary process without requiring any pure spectra or having previous knowledge about the presence of the interferences. The proposed hard–soft method based on net analyte signal (HS-NAS) only needs a chemical model for one of the species involved in the reaction under study. The reliability of the method was examined by applying it to the measured data and spectrum of the known real systems of Fe2+–azithromycin and Ca2+–tetracycline.
Keywords: Multivariate curve resolution; Net anayte signal; Hard–soft method; Complex formation; Azithromycin; Tetracycline
Spectrophotometric study of complex formation equilibria in the presence of interference using hard–soft net analyte signal method: Application to drug–metal complexation by Bahram Hemmateenejad; Mohsen Nekoeinia; Ghodratollah Absalan (pp. 178-186).
In this article, the ability of a new and efficient hard–soft method, previously proposed by our research group, is reported for modeling of the complex formation equilibria in the presence of interferences. This method is based on the net analyte signal (NAS) concept, which is a part of total signal that is directly related to the concentration of the component of interest. It monitors the concentration changes of any chemical species involved in the evolutionary process without requiring any pure spectra or having previous knowledge about the presence of the interferences. The proposed hard–soft method based on net analyte signal (HS-NAS) only needs a chemical model for one of the species involved in the reaction under study. The reliability of the method was examined by applying it to the measured data and spectrum of the known real systems of Fe2+–azithromycin and Ca2+–tetracycline.
Keywords: Multivariate curve resolution; Net anayte signal; Hard–soft method; Complex formation; Azithromycin; Tetracycline
Electrochemical detection of ultratrace nitroaromatic explosives using ordered mesoporous carbon by Jianfeng Zang; Chun Xian Guo; Fengping Hu; Lei Yu; Chang Ming Li (pp. 187-191).
A sensitive electrochemical sensor has been fabricated to detect ultratrace nitroaromatic explosives using ordered mesoporus carbon (OMC). OMC was synthesized and characterized by scanning electron microscopy, transmission electron microscopy and nitrogen adsorption/desorption measurements. Glassy carbon electrodes functionalized with OMC show high sensitivity of 62.7μAcm−2 per ppb towards 2,4,6-trinitrotoluene (TNT). By comparison with other materials such as carbon nanotubes and ordered mesoporous silica, it is found that the high performance of OMC toward sensing TNT is attributed to its large specific surface area and fast electron transfer capability. As low as 0.2ppb TNT, 1ppb 2,4-dinitrotoluene and 1ppb 1,3-dinitrobenzene can be detected on OMC based electrodes. This work renders new opportunities to detect ultratrace explosives for applications of environment protections and home securities against chemical warfare agents.
Keywords: 2,4,6-Tirnitrotoluene; Ordered mesoporous carbon; Ultratrace explosive detection; Electrochemical sensors
Electrochemical detection of ultratrace nitroaromatic explosives using ordered mesoporous carbon by Jianfeng Zang; Chun Xian Guo; Fengping Hu; Lei Yu; Chang Ming Li (pp. 187-191).
A sensitive electrochemical sensor has been fabricated to detect ultratrace nitroaromatic explosives using ordered mesoporus carbon (OMC). OMC was synthesized and characterized by scanning electron microscopy, transmission electron microscopy and nitrogen adsorption/desorption measurements. Glassy carbon electrodes functionalized with OMC show high sensitivity of 62.7μAcm−2 per ppb towards 2,4,6-trinitrotoluene (TNT). By comparison with other materials such as carbon nanotubes and ordered mesoporous silica, it is found that the high performance of OMC toward sensing TNT is attributed to its large specific surface area and fast electron transfer capability. As low as 0.2ppb TNT, 1ppb 2,4-dinitrotoluene and 1ppb 1,3-dinitrobenzene can be detected on OMC based electrodes. This work renders new opportunities to detect ultratrace explosives for applications of environment protections and home securities against chemical warfare agents.
Keywords: 2,4,6-Tirnitrotoluene; Ordered mesoporous carbon; Ultratrace explosive detection; Electrochemical sensors
Multicomponent analysis of drinking water by a voltammetric electronic tongue by Fredrik Winquist; John Olsson; Mats Eriksson (pp. 192-197).
A voltammetric electronic tongue is described that was used for multicomponent analysis of drinking water. Measurements were performed on drinking water from a tap and injections of the compounds NaCl, NaN3, NaHSO3, ascorbic acid, NaOCl and yeast suspensions could be identified by use of principal component analysis (PCA). A model based on partial least square (PLS) was developed for the simultaneously prediction of identification and concentration of the compounds NaCl, NaHSO3 and NaOCl. By utilizing this type of non-selective sensor technique for water quality surveillance, it will be feasible to detect a plurality of events without the need of a specific sensor for each type of event.
Keywords: Electronic tongue; Drinking water; Voltammetry; Chemometry
Multicomponent analysis of drinking water by a voltammetric electronic tongue by Fredrik Winquist; John Olsson; Mats Eriksson (pp. 192-197).
A voltammetric electronic tongue is described that was used for multicomponent analysis of drinking water. Measurements were performed on drinking water from a tap and injections of the compounds NaCl, NaN3, NaHSO3, ascorbic acid, NaOCl and yeast suspensions could be identified by use of principal component analysis (PCA). A model based on partial least square (PLS) was developed for the simultaneously prediction of identification and concentration of the compounds NaCl, NaHSO3 and NaOCl. By utilizing this type of non-selective sensor technique for water quality surveillance, it will be feasible to detect a plurality of events without the need of a specific sensor for each type of event.
Keywords: Electronic tongue; Drinking water; Voltammetry; Chemometry
Synthesis and study of a molecularly imprinted polymer for the specific extraction of indole alkaloids from Catharanthus roseus extracts by C. Lopez; B. Claude; Ph. Morin; J.-P. Max; R. Pena; J.-P. Ribet (pp. 198-205).
Two molecularly imprinted polymers (MIP) for catharanthine and vindoline have been synthesized in order to specifically extract these natural indole alkaloids from Catharanthus roseus by solid-phase extraction (SPE). Each MIP was prepared by thermal polymerisation using catharanthine (or vindoline) as template, methacrylic acid (or itaconic acid) as functional monomer, ethylene glycol dimethacrylate (EDMA) as cross-linking agent and acetonitrile (or acetone) as porogenic solvent.For catharanthine-MIP, a SPE protocol (ACN–AcOH 99/1 washing and MeOH–AcOH 90/10 elution) allows a good MIP/NIP selectivity (imprinting factor 12.6). The specificity of catharanthine-MIP versus related bisindole alkaloids was assessed by cross-reactivity study. The catharanthine-MIP specifically retained catharanthine and its N-oxide analogue but displayed a weak cross-reactivity for other Vinca alkaloids (vinorelbine, vincristine, vinblastine, vindoline, vinflunine). It appears that the catharanthine-like unit of these molecules are hardly trapped in catharanthine cavities located in the MIP, probably due to the sterical hindrance of the vindoline moiety. Finally, the MIP-SPE applied to C. roseus extract enabled quantitative recovery of catharanthine (101%) and the total removal of vindoline. Its capacity was determined and was equal to 2.43μmolg−1.Vindoline is a weaker base than catharanthine, so the vindoline-MIP was achieved with a strong acidic monomer (itaconic acid) to increase vindoline–monomer interactions and a modified washing solvent (ACN–HCOOH 99/1) to reduce non-specific interactions. The influence of the amount of HCOOH (protic modifier) percolated during the washing step upon the elution yield and the imprinting factor for vindoline was investigated. This preliminary optimisation of the washing step, and in particular the number of moles of acid percolated, seems useful to emphasize the use of MIP in conditions of high selectivity or high yield. A compromise was obtained with an imprinting factor equal to 7.6 and an elution recovery of 33%. However MIP-vindoline failed to achieve a specific extraction of vindoline since catharanthine was also extracted probably because of strong non-specific interactions occurring between catharanthine and the sorbent.
Keywords: Molecularly imprinted polymer; Indole alkaloids; Catharanthus roseus; Catharanthine; Vindoline; Solid-phase extraction; Plant extract; Imprinting factor
Synthesis and study of a molecularly imprinted polymer for the specific extraction of indole alkaloids from Catharanthus roseus extracts by C. Lopez; B. Claude; Ph. Morin; J.-P. Max; R. Pena; J.-P. Ribet (pp. 198-205).
Two molecularly imprinted polymers (MIP) for catharanthine and vindoline have been synthesized in order to specifically extract these natural indole alkaloids from Catharanthus roseus by solid-phase extraction (SPE). Each MIP was prepared by thermal polymerisation using catharanthine (or vindoline) as template, methacrylic acid (or itaconic acid) as functional monomer, ethylene glycol dimethacrylate (EDMA) as cross-linking agent and acetonitrile (or acetone) as porogenic solvent.For catharanthine-MIP, a SPE protocol (ACN–AcOH 99/1 washing and MeOH–AcOH 90/10 elution) allows a good MIP/NIP selectivity (imprinting factor 12.6). The specificity of catharanthine-MIP versus related bisindole alkaloids was assessed by cross-reactivity study. The catharanthine-MIP specifically retained catharanthine and its N-oxide analogue but displayed a weak cross-reactivity for other Vinca alkaloids (vinorelbine, vincristine, vinblastine, vindoline, vinflunine). It appears that the catharanthine-like unit of these molecules are hardly trapped in catharanthine cavities located in the MIP, probably due to the sterical hindrance of the vindoline moiety. Finally, the MIP-SPE applied to C. roseus extract enabled quantitative recovery of catharanthine (101%) and the total removal of vindoline. Its capacity was determined and was equal to 2.43μmolg−1.Vindoline is a weaker base than catharanthine, so the vindoline-MIP was achieved with a strong acidic monomer (itaconic acid) to increase vindoline–monomer interactions and a modified washing solvent (ACN–HCOOH 99/1) to reduce non-specific interactions. The influence of the amount of HCOOH (protic modifier) percolated during the washing step upon the elution yield and the imprinting factor for vindoline was investigated. This preliminary optimisation of the washing step, and in particular the number of moles of acid percolated, seems useful to emphasize the use of MIP in conditions of high selectivity or high yield. A compromise was obtained with an imprinting factor equal to 7.6 and an elution recovery of 33%. However MIP-vindoline failed to achieve a specific extraction of vindoline since catharanthine was also extracted probably because of strong non-specific interactions occurring between catharanthine and the sorbent.
Keywords: Molecularly imprinted polymer; Indole alkaloids; Catharanthus roseus; Catharanthine; Vindoline; Solid-phase extraction; Plant extract; Imprinting factor
Self-doped polyaniline as new polyaniline substitute for solid-phase microextraction by Ali Mehdinia; Fateme Roohi; Ali Jabbari; Mohammad Reza Manafi (pp. 206-211).
This work is a first study on extraction efficiency and thermal stability of nano-structured self-doped polyaniline (SPAN) as a coating of solid-phase microextraction (SPME) fibers. SPAN-based fibers were prepared using electrochemical deposition on platinum wires. The particle sizes of prepared nano-structure were in the range of 50–100nm. Extraction properties of the fiber to 1,4-dioxane were examined using headspace solid-phase microextraction (HS-SPME) coupled to gas chromatography-flame ionization detection (GC-FID). The results have proved higher thermal stability of the proposed fiber compared to common PANI fiber. The SPAN coating was proved to be very stable at relatively high temperatures (up to 350°C) with high extraction capacity and long lifespan (more than 50 times). Therefore, it can be a good substitute of polyaniline (PANI) as a SPME coating. The extraction procedure was optimized by selecting the appropriate extraction parameters including extraction time, extraction temperature, salt concentration, stirring rate and headspace volume. Calibration graph was linear in the concentration range of 1–100ngmL−1 ( R2>0.993) with detection limit of 0.1ngmL−1. Single fiber and fiber-to-fiber repeatability were lower than 6.0% and 10.4%, respectively. Different water samples were analyzed as real samples and good recoveries (98–120%) were obtained.
Keywords: Self-doped polyaniline; Solid-phase microextraction; 1,4-Dioxane; Nano-structure
Self-doped polyaniline as new polyaniline substitute for solid-phase microextraction by Ali Mehdinia; Fateme Roohi; Ali Jabbari; Mohammad Reza Manafi (pp. 206-211).
This work is a first study on extraction efficiency and thermal stability of nano-structured self-doped polyaniline (SPAN) as a coating of solid-phase microextraction (SPME) fibers. SPAN-based fibers were prepared using electrochemical deposition on platinum wires. The particle sizes of prepared nano-structure were in the range of 50–100nm. Extraction properties of the fiber to 1,4-dioxane were examined using headspace solid-phase microextraction (HS-SPME) coupled to gas chromatography-flame ionization detection (GC-FID). The results have proved higher thermal stability of the proposed fiber compared to common PANI fiber. The SPAN coating was proved to be very stable at relatively high temperatures (up to 350°C) with high extraction capacity and long lifespan (more than 50 times). Therefore, it can be a good substitute of polyaniline (PANI) as a SPME coating. The extraction procedure was optimized by selecting the appropriate extraction parameters including extraction time, extraction temperature, salt concentration, stirring rate and headspace volume. Calibration graph was linear in the concentration range of 1–100ngmL−1 ( R2>0.993) with detection limit of 0.1ngmL−1. Single fiber and fiber-to-fiber repeatability were lower than 6.0% and 10.4%, respectively. Different water samples were analyzed as real samples and good recoveries (98–120%) were obtained.
Keywords: Self-doped polyaniline; Solid-phase microextraction; 1,4-Dioxane; Nano-structure
A novel needle trap sorbent based on carbon nanotube-sol–gel for microextraction of polycyclic aromatic hydrocarbons from aquatic media by Habib Bagheri; Zahra Ayazi; Ali Aghakhani (pp. 212-220).
A new type of composite material based on carbon nanotubes (CNTs) and sol–gel chemistry was prepared and used as sorbent for needle trap device (NTD). The synthesized composite was prepared in a way to disperse CNTs molecules in a sol–gel polymeric network. CNT/silica composites with different CNT doping levels were successfully prepared, and the extraction capability of each composite was evaluated. Effects of surfactant and the oxidation duration of CNTs on the extraction efficiency of synthesized composites were also investigated. The applicability of the synthesized sorbent was examined by developing a method based on needle trap extraction (NTE) and gas chromatography mass spectrometry detection (GC–MS) for the determination of polycyclic aromatic hydrocarbons (PAHs) in aqueous samples. Important parameters influencing the extraction process were optimized and an extraction time of 30min at 50°C and sampling flow rate of 2.5mLmin−1 gave maximum peak area, when NaCl (15%, w/v) was added to the aqueous sample. The linearity for acenaphthene, acenaphthylene and fluorene was in the concentration range of 0.01–20ngmL−1 and for naphthalene and anthracene was in the range of 0.1–50ngmL−1. Limits of detection was 0.001ngmL−1, for acenaphthene, acenaphthylene and fluorene, and 0.01ngmL−1, for naphthalene and anthracene using time-scheduled selected ion monitoring (SIM) mode, and the RSD% values ( n=3) were all below 11.2% at the 1ngmL−1 level. The developed method was successfully applied to real water samples while the relative recovery percentages obtained for the spiked water samples were from 73.8 to 113.8%.
Keywords: Needle trap extraction; Carbon nanotube; Sol–gel; Polycyclic aromatic hydrocarbons; Water analysis
A novel needle trap sorbent based on carbon nanotube-sol–gel for microextraction of polycyclic aromatic hydrocarbons from aquatic media by Habib Bagheri; Zahra Ayazi; Ali Aghakhani (pp. 212-220).
A new type of composite material based on carbon nanotubes (CNTs) and sol–gel chemistry was prepared and used as sorbent for needle trap device (NTD). The synthesized composite was prepared in a way to disperse CNTs molecules in a sol–gel polymeric network. CNT/silica composites with different CNT doping levels were successfully prepared, and the extraction capability of each composite was evaluated. Effects of surfactant and the oxidation duration of CNTs on the extraction efficiency of synthesized composites were also investigated. The applicability of the synthesized sorbent was examined by developing a method based on needle trap extraction (NTE) and gas chromatography mass spectrometry detection (GC–MS) for the determination of polycyclic aromatic hydrocarbons (PAHs) in aqueous samples. Important parameters influencing the extraction process were optimized and an extraction time of 30min at 50°C and sampling flow rate of 2.5mLmin−1 gave maximum peak area, when NaCl (15%, w/v) was added to the aqueous sample. The linearity for acenaphthene, acenaphthylene and fluorene was in the concentration range of 0.01–20ngmL−1 and for naphthalene and anthracene was in the range of 0.1–50ngmL−1. Limits of detection was 0.001ngmL−1, for acenaphthene, acenaphthylene and fluorene, and 0.01ngmL−1, for naphthalene and anthracene using time-scheduled selected ion monitoring (SIM) mode, and the RSD% values ( n=3) were all below 11.2% at the 1ngmL−1 level. The developed method was successfully applied to real water samples while the relative recovery percentages obtained for the spiked water samples were from 73.8 to 113.8%.
Keywords: Needle trap extraction; Carbon nanotube; Sol–gel; Polycyclic aromatic hydrocarbons; Water analysis
Urine stability and steroid profile: Towards a screening index of urine sample degradation for anti-doping purpose by Monica Mazzarino; Maria Gabriella Abate; Roberto Alocci; Francesca Rossi; Raffaella Stinchelli; Francesco Molaioni; Xavier de la Torre; Francesco Botrè (pp. 221-226).
The presence of microorganisms in urine samples, under favourable conditions of storage and transportation, may alter the concentration of steroid hormones, thus altering the correct evaluation of the urinary steroid profile in doping control analysis. According to the rules of the World Anti-Doping Agency (WADA technical document TD2004 EAAS), a testosterone deconjugation higher than 5% and the presence of 5α-androstane-3,17-dione and 5β-androstane-3,17-dione in the deconjugated fraction, are reliable indicators of urine degradation. The determination of these markers would require an additional quantitative analysis since the steroids screening analysis, in anti-doping laboratories, is performed in the total (free+conjugated) fraction. The aim of this work is therefore to establish reliable threshold values for some representative compounds (namely 5α-androstane-3,17-dione and 5β-androstane-3,17-dione) in the total fraction in order to predict directly at the screening stage the potential microbial degradation of the urine samples. Preliminary evidence on the most suitable degradation indexes has been obtained by measuring the urinary concentration of testosterone, epitestosterone, 5α-androstane-3,17-dione and 5β-androstane-3,17-dione by gas chromatography–mass spectrometric every day for 15 days in the deconjugated, glucuronide and total fraction of 10 pools of urines from 60 healthy subjects, stored under different pH and temperature conditions, and isolating the samples with one or more markers of degradation according to the WADA technical document TD2004EAAS. The threshold values for 5α-androstane-3,17-dione and 5β-androstane-3,17-dione were therefore obtained correlating the testosterone deconjugation rate with the urinary concentrations of 5α-androstane-3,17-dione and 5β-androstane-3,17-dione in the total fraction. The threshold values suggested as indexes of urine degradation in the total fraction were: 10ngmL−1 for 5α-androstane-3,17-dione and 20ngmL−1 for 5β-androstane-3,17-dione. The validity of this approach was confirmed by the analysis of routine samples for more than five months (i.e. on a total of more than 4000 urine samples): samples with a concentration of total 5α-androstane-3,17-dione and 5β-androstane-3,17-dione higher than the threshold values showed a percentage of free testosterone higher than 5 of its total amount; whereas free testosterone in a percentage higher than 5 of its total amount was not detected in urines with a concentration of total 5α-androstane-3,17-dione and 5β-androstane-3,17-dione lower than the threshold values.
Keywords: Urine degradation; Steroid profile; GC–MS; Anti-doping analysis
Urine stability and steroid profile: Towards a screening index of urine sample degradation for anti-doping purpose by Monica Mazzarino; Maria Gabriella Abate; Roberto Alocci; Francesca Rossi; Raffaella Stinchelli; Francesco Molaioni; Xavier de la Torre; Francesco Botrè (pp. 221-226).
The presence of microorganisms in urine samples, under favourable conditions of storage and transportation, may alter the concentration of steroid hormones, thus altering the correct evaluation of the urinary steroid profile in doping control analysis. According to the rules of the World Anti-Doping Agency (WADA technical document TD2004 EAAS), a testosterone deconjugation higher than 5% and the presence of 5α-androstane-3,17-dione and 5β-androstane-3,17-dione in the deconjugated fraction, are reliable indicators of urine degradation. The determination of these markers would require an additional quantitative analysis since the steroids screening analysis, in anti-doping laboratories, is performed in the total (free+conjugated) fraction. The aim of this work is therefore to establish reliable threshold values for some representative compounds (namely 5α-androstane-3,17-dione and 5β-androstane-3,17-dione) in the total fraction in order to predict directly at the screening stage the potential microbial degradation of the urine samples. Preliminary evidence on the most suitable degradation indexes has been obtained by measuring the urinary concentration of testosterone, epitestosterone, 5α-androstane-3,17-dione and 5β-androstane-3,17-dione by gas chromatography–mass spectrometric every day for 15 days in the deconjugated, glucuronide and total fraction of 10 pools of urines from 60 healthy subjects, stored under different pH and temperature conditions, and isolating the samples with one or more markers of degradation according to the WADA technical document TD2004EAAS. The threshold values for 5α-androstane-3,17-dione and 5β-androstane-3,17-dione were therefore obtained correlating the testosterone deconjugation rate with the urinary concentrations of 5α-androstane-3,17-dione and 5β-androstane-3,17-dione in the total fraction. The threshold values suggested as indexes of urine degradation in the total fraction were: 10ngmL−1 for 5α-androstane-3,17-dione and 20ngmL−1 for 5β-androstane-3,17-dione. The validity of this approach was confirmed by the analysis of routine samples for more than five months (i.e. on a total of more than 4000 urine samples): samples with a concentration of total 5α-androstane-3,17-dione and 5β-androstane-3,17-dione higher than the threshold values showed a percentage of free testosterone higher than 5 of its total amount; whereas free testosterone in a percentage higher than 5 of its total amount was not detected in urines with a concentration of total 5α-androstane-3,17-dione and 5β-androstane-3,17-dione lower than the threshold values.
Keywords: Urine degradation; Steroid profile; GC–MS; Anti-doping analysis
Analysis of bisphenols in soft drinks by on-line solid phase extraction fast liquid chromatography–tandem mass spectrometry by H. Gallart-Ayala; E. Moyano; M.T. Galceran (pp. 227-233).
In this study, an automated on-line solid-phase extraction coupled to fast liquid chromatography–tandem mass spectrometry (on-line SPE fast LC–MS/MS) method was developed for the simultaneous analysis of bisphenol A (BPA), bisphenol F (BPF), bisphenol E (BPE), bisphenol B (BPB) and bisphenol S (BPS) in canned soft drinks without any previous sample treatment. A C18 (12μm particle size) loading column was used for the SPE on-line preconcentration before the liquid chromatography baseline separation of bisphenol compounds using a C18 Fused-Core™ (50mm×2.1mm i.d.) column, which took less than 3min. Gradient elution and heated electrospray were used to reduce matrix effect and improve ionization efficiency. To select the most intense and selective transitions, fragmentation studies were performed by multiple-stage mass spectrometry in an ion trap mass analyzer and tandem mass spectrometry in a triple quadrupole instrument, this latter instrument being used for quantitation in SRM mode. Quality parameters of the method were established and we obtained a simple, fast, reproducible (RSD values lower than 10%) and accurate (precision higher than 93%) method for the analysis of bisphenols in canned soft drinks at the ngL−1 level using matrix-matched calibration.
Keywords: Bisphenols; Soft drink beverages; Fused-Core™ column; On-line solid phase extraction (SPE)
Analysis of bisphenols in soft drinks by on-line solid phase extraction fast liquid chromatography–tandem mass spectrometry by H. Gallart-Ayala; E. Moyano; M.T. Galceran (pp. 227-233).
In this study, an automated on-line solid-phase extraction coupled to fast liquid chromatography–tandem mass spectrometry (on-line SPE fast LC–MS/MS) method was developed for the simultaneous analysis of bisphenol A (BPA), bisphenol F (BPF), bisphenol E (BPE), bisphenol B (BPB) and bisphenol S (BPS) in canned soft drinks without any previous sample treatment. A C18 (12μm particle size) loading column was used for the SPE on-line preconcentration before the liquid chromatography baseline separation of bisphenol compounds using a C18 Fused-Core™ (50mm×2.1mm i.d.) column, which took less than 3min. Gradient elution and heated electrospray were used to reduce matrix effect and improve ionization efficiency. To select the most intense and selective transitions, fragmentation studies were performed by multiple-stage mass spectrometry in an ion trap mass analyzer and tandem mass spectrometry in a triple quadrupole instrument, this latter instrument being used for quantitation in SRM mode. Quality parameters of the method were established and we obtained a simple, fast, reproducible (RSD values lower than 10%) and accurate (precision higher than 93%) method for the analysis of bisphenols in canned soft drinks at the ngL−1 level using matrix-matched calibration.
Keywords: Bisphenols; Soft drink beverages; Fused-Core™ column; On-line solid phase extraction (SPE)
A signal-on electrogenerated chemiluminescent biosensor for lead ion based on DNAzyme by Fen Ma; Bo Sun; Honglan Qi; Hongge Zhang; Qiang Gao; Chengxiao Zhang (pp. 234-241).
A highly reproducible and sensitive signal-on electrogenerated chemiluminescence (ECL) biosensor based on the DNAzyme for the determination of lead ion was developed. The ECL biosensor was fabricated by covalently coupling 5′-amino-DNAzyme-tagged with ruthenium bis (2,2′-bipyridine) (2,2′-bipyridine-4,4′-dicarboxylic acid)-ethylenediamine (Ru1-17E′) onto the surface of graphite electrode modified with 4-aminobenzoic acid, and then a DNA substrate with a ribonucleotide adenosine hybridized with Ru1-17E′ on the electrode. Upon binding of Pb2+ to the Ru1-17E′ to form a complex which catalyzed the cleavage of the DNA substrate, the double-stranded DNA was dissociated and thus led to a high ECL signal. The signal linearly increases with the concentration of Pb2+ in the range from 5.0 to 80pM with a detection limit of 1.4pM and a relative standard derivation of 2.3%. This work demonstrates that using DNAzyme tagged with ruthenium complex as an ECL probe and covalently coupling method for the fabrication of the ECL biosensor with high sensitivity, good stability and significant regeneration ability is promising approach.
Keywords: Biosensor; Electrogenerated chemiluminescence; DNAzyme; Lead ion
A signal-on electrogenerated chemiluminescent biosensor for lead ion based on DNAzyme by Fen Ma; Bo Sun; Honglan Qi; Hongge Zhang; Qiang Gao; Chengxiao Zhang (pp. 234-241).
A highly reproducible and sensitive signal-on electrogenerated chemiluminescence (ECL) biosensor based on the DNAzyme for the determination of lead ion was developed. The ECL biosensor was fabricated by covalently coupling 5′-amino-DNAzyme-tagged with ruthenium bis (2,2′-bipyridine) (2,2′-bipyridine-4,4′-dicarboxylic acid)-ethylenediamine (Ru1-17E′) onto the surface of graphite electrode modified with 4-aminobenzoic acid, and then a DNA substrate with a ribonucleotide adenosine hybridized with Ru1-17E′ on the electrode. Upon binding of Pb2+ to the Ru1-17E′ to form a complex which catalyzed the cleavage of the DNA substrate, the double-stranded DNA was dissociated and thus led to a high ECL signal. The signal linearly increases with the concentration of Pb2+ in the range from 5.0 to 80pM with a detection limit of 1.4pM and a relative standard derivation of 2.3%. This work demonstrates that using DNAzyme tagged with ruthenium complex as an ECL probe and covalently coupling method for the fabrication of the ECL biosensor with high sensitivity, good stability and significant regeneration ability is promising approach.
Keywords: Biosensor; Electrogenerated chemiluminescence; DNAzyme; Lead ion
High-sensitivity biosensors fabricated by tailoring the localized surface plasmon resonance property of core–shell gold nanorods by Haowen Huang; Shaowen Huang; Shishan Yuan; Caiting Qu; Yi Chen; Zhongjian Xu; Bo Liao; Yunlong Zeng; Paul K. Chu (pp. 242-247).
An enhanced sensitive biosensor has been developed to detect biological targets by tailoring the localized surface plasmon resonance property of core–shell gold nanorods. In this new concept, a shell layer is produced on gold nanorods by generating a layer of chalcogenide on the gold nanorod surface after attachment of the recognition reagent, namely, goat IgG and antigen of schistosomiasis japonica. The bioactivity of these attached biomolecules is retained and the sensitivity of this biosensor is thus enhanced significantly. The plasmonic properties of the gold nanorods attached with the biomolecules can be adjusted and the plasmon resonance wavelength can be red-shifted up to several hundred nanometers in the visible or near infrared (NIR) region, which is extremely important to biosensing applications. This leads to a lager red-shift in the localized surface plasmon resonance absorption compared to the original gold nanorod-based sensor and hence offers greatly enhanced sensitivity in the detection of schistosomiasis japonica. The human serum infected with schistosomiasis japonica diluted to 1:50,000 (volume ratio, serum/buffer solution) can be detected readily. The technique offers enhanced sensitivity and can be easily extended to other sensing applications based on not only immuno-recognition but also other types of specific reactions.
Keywords: Localized surface plasmon resonance; Gold nanorod composite; Schistosomiasis japonica; Biosensor
High-sensitivity biosensors fabricated by tailoring the localized surface plasmon resonance property of core–shell gold nanorods by Haowen Huang; Shaowen Huang; Shishan Yuan; Caiting Qu; Yi Chen; Zhongjian Xu; Bo Liao; Yunlong Zeng; Paul K. Chu (pp. 242-247).
An enhanced sensitive biosensor has been developed to detect biological targets by tailoring the localized surface plasmon resonance property of core–shell gold nanorods. In this new concept, a shell layer is produced on gold nanorods by generating a layer of chalcogenide on the gold nanorod surface after attachment of the recognition reagent, namely, goat IgG and antigen of schistosomiasis japonica. The bioactivity of these attached biomolecules is retained and the sensitivity of this biosensor is thus enhanced significantly. The plasmonic properties of the gold nanorods attached with the biomolecules can be adjusted and the plasmon resonance wavelength can be red-shifted up to several hundred nanometers in the visible or near infrared (NIR) region, which is extremely important to biosensing applications. This leads to a lager red-shift in the localized surface plasmon resonance absorption compared to the original gold nanorod-based sensor and hence offers greatly enhanced sensitivity in the detection of schistosomiasis japonica. The human serum infected with schistosomiasis japonica diluted to 1:50,000 (volume ratio, serum/buffer solution) can be detected readily. The technique offers enhanced sensitivity and can be easily extended to other sensing applications based on not only immuno-recognition but also other types of specific reactions.
Keywords: Localized surface plasmon resonance; Gold nanorod composite; Schistosomiasis japonica; Biosensor
Determination of perfluorinated compounds in fish fillet homogenates: Method validation and application to fillet homogenates from the Mississippi River by Michelle Duval Malinsky; Cliffton B. Jacoby; William K. Reagen (pp. 248-257).
We report herein a simple protein precipitation extraction-liquid chromatography tandem mass spectrometry (LC/MS/MS) method, validation, and application for the analysis of perfluorinated carboxylic acids (C7–C12), perfluorinated sulfonic acids (C4, C6, and C8), and perfluorooctane sulfonamide (FOSA) in fish fillet tissue. The method combines a rapid homogenization and protein precipitation tissue extraction procedure using stable-isotope internal standard (IS) calibration. Method validation in bluegill ( Lepomis macrochirus) fillet tissue evaluated the following: (1) method accuracy and precision in both extracted matrix-matched calibration and solvent (unextracted) calibration, (2) quantitation of mixed branched and linear isomers of perfluorooctanoate (PFOA) and perfluorooctanesulfonate (PFOS) with linear isomer calibration, (3) quantitation of low level (ppb) perfluorinated compounds (PFCs) in the presence of high level (ppm) PFOS, and (4) specificity from matrix interferences. Both calibration techniques produced method accuracy of at least 100±13% with a precision (%RSD) ≤18% for all target analytes. Method accuracy and precision results for fillet samples from nine different fish species taken from the Mississippi River in 2008 and 2009 are also presented.
Keywords: Perfluorinated compounds; Perfluorooctanesulfonate; Perfluorooctanoic acid; PFOS; PFOA; Method validation; Liquid chromatography–tandem mass spectrometry (LC/MS/MS); Matrix-matched calibration; Fish tissues
Determination of perfluorinated compounds in fish fillet homogenates: Method validation and application to fillet homogenates from the Mississippi River by Michelle Duval Malinsky; Cliffton B. Jacoby; William K. Reagen (pp. 248-257).
We report herein a simple protein precipitation extraction-liquid chromatography tandem mass spectrometry (LC/MS/MS) method, validation, and application for the analysis of perfluorinated carboxylic acids (C7–C12), perfluorinated sulfonic acids (C4, C6, and C8), and perfluorooctane sulfonamide (FOSA) in fish fillet tissue. The method combines a rapid homogenization and protein precipitation tissue extraction procedure using stable-isotope internal standard (IS) calibration. Method validation in bluegill ( Lepomis macrochirus) fillet tissue evaluated the following: (1) method accuracy and precision in both extracted matrix-matched calibration and solvent (unextracted) calibration, (2) quantitation of mixed branched and linear isomers of perfluorooctanoate (PFOA) and perfluorooctanesulfonate (PFOS) with linear isomer calibration, (3) quantitation of low level (ppb) perfluorinated compounds (PFCs) in the presence of high level (ppm) PFOS, and (4) specificity from matrix interferences. Both calibration techniques produced method accuracy of at least 100±13% with a precision (%RSD) ≤18% for all target analytes. Method accuracy and precision results for fillet samples from nine different fish species taken from the Mississippi River in 2008 and 2009 are also presented.
Keywords: Perfluorinated compounds; Perfluorooctanesulfonate; Perfluorooctanoic acid; PFOS; PFOA; Method validation; Liquid chromatography–tandem mass spectrometry (LC/MS/MS); Matrix-matched calibration; Fish tissues