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Analytical and Bioanalytical Chemistry (v.384, #6)
Optical and electrochemical detection techniques for cell-based microfluidic systems by Changqing Yi; Qi Zhang; Cheuk-Wing Li; Jun Yang; Jianlong Zhao; Mengsu Yang (pp. 1259-1268).
The ability to fabricate microfluidic systems with complex structures and with compatible dimensions between the microfluidics and biological cells have attracted significant attention in the development of microchips for analyzing the biophysical and biochemical functions of cells. Just as cell-based microfluidics have become a versatile tool for biosensing, diagnostics, drug screening and biological research, detector modules for cell-based microfluidics have also undergone major development over the past decade. This review focuses on detection methods commonly used in cell-based microfluidic systems, and provides a general survey and an in-depth look at recent developments in optical and electrochemical detection methods for microfluidic applications for biological systems, particularly cell analysis. Selected examples are used to illustrate applications of these detection systems and their advantages and weaknesses.
Keywords: Cell-based microfluidics; Optical detection techniques; Electrochemical detection techniques
Optical and electrochemical detection techniques for cell-based microfluidic systems by Changqing Yi; Qi Zhang; Cheuk-Wing Li; Jun Yang; Jianlong Zhao; Mengsu Yang (pp. 1259-1268).
The ability to fabricate microfluidic systems with complex structures and with compatible dimensions between the microfluidics and biological cells have attracted significant attention in the development of microchips for analyzing the biophysical and biochemical functions of cells. Just as cell-based microfluidics have become a versatile tool for biosensing, diagnostics, drug screening and biological research, detector modules for cell-based microfluidics have also undergone major development over the past decade. This review focuses on detection methods commonly used in cell-based microfluidic systems, and provides a general survey and an in-depth look at recent developments in optical and electrochemical detection methods for microfluidic applications for biological systems, particularly cell analysis. Selected examples are used to illustrate applications of these detection systems and their advantages and weaknesses.
Keywords: Cell-based microfluidics; Optical detection techniques; Electrochemical detection techniques
Development and validation of a sensitive and fast chemiluminescent enzyme immunoassay for the detection of genetically modified maize by A. Roda; M. Mirasoli; M. Guardigli; E. Michelini; P. Simoni; M. Magliulo (pp. 1269-1275).
Proteins from the Cry 1 family, in particular Cry 1Ab, are commonly expressed in genetically modified Bt maize in order to control chewing insect pests. A sensitive chemiluminescent sandwich enzyme immunoassay for the detection of Cry1Ab protein from genetically modified Bt maize has been developed and validated. A Cry1Ab protein-specific antibody was immobilized on 96- or 384-well microtiter plates in order to capture the Cry1Ab toxin in the sample; the bound toxin was then detected by employing a second anti-Cry1Ab antibody and a horseradish peroxidase-labeled anti-antibody, followed by measurement of the enzyme activity with an enhanced chemiluminescent system. The chemiluminescent assay fulfilled all the requirements of accuracy and precision and exhibited limits of detection of a few pg mL−1 Cry1Ab (3 or 5 pg mL−1, depending on the assay format), which are significantly lower than that achievable using conventional colorimetric detection of peroxidase activity and also represent an improvement compared to previously developed Cry1Ab immunoassays. High-throughput analysis can be performed using the 384-well microtiter plate format immunoassay, which also allows one to reduce the consumption of samples and reagents. Validation of the assay, performed by analyzing certified reference materials, proved that the immunoassay is able to detect the presence of the Cry1Ab protein in certified reference samples containing as low as 0.1% of MON 810 genetically modified Bt maize. This value is below the threshold requiring mandatory labeling of foods containing genetically modified material according to the actual EU regulation.
Keywords: Chemiluminescence; Cry1Ab protein; Genetically modified maize; High-throughput screening; Immunoassay
Development and validation of a sensitive and fast chemiluminescent enzyme immunoassay for the detection of genetically modified maize by A. Roda; M. Mirasoli; M. Guardigli; E. Michelini; P. Simoni; M. Magliulo (pp. 1269-1275).
Proteins from the Cry 1 family, in particular Cry 1Ab, are commonly expressed in genetically modified Bt maize in order to control chewing insect pests. A sensitive chemiluminescent sandwich enzyme immunoassay for the detection of Cry1Ab protein from genetically modified Bt maize has been developed and validated. A Cry1Ab protein-specific antibody was immobilized on 96- or 384-well microtiter plates in order to capture the Cry1Ab toxin in the sample; the bound toxin was then detected by employing a second anti-Cry1Ab antibody and a horseradish peroxidase-labeled anti-antibody, followed by measurement of the enzyme activity with an enhanced chemiluminescent system. The chemiluminescent assay fulfilled all the requirements of accuracy and precision and exhibited limits of detection of a few pg mL−1 Cry1Ab (3 or 5 pg mL−1, depending on the assay format), which are significantly lower than that achievable using conventional colorimetric detection of peroxidase activity and also represent an improvement compared to previously developed Cry1Ab immunoassays. High-throughput analysis can be performed using the 384-well microtiter plate format immunoassay, which also allows one to reduce the consumption of samples and reagents. Validation of the assay, performed by analyzing certified reference materials, proved that the immunoassay is able to detect the presence of the Cry1Ab protein in certified reference samples containing as low as 0.1% of MON 810 genetically modified Bt maize. This value is below the threshold requiring mandatory labeling of foods containing genetically modified material according to the actual EU regulation.
Keywords: Chemiluminescence; Cry1Ab protein; Genetically modified maize; High-throughput screening; Immunoassay
Fractionation of selenium-containing proteins in serum by multiaffinity liquid chromatography before size-exclusion chromatography–ICPMS by Òscar Palacios; Jorge Ruiz Encinar; Dirk Schaumlöffel; Ryszard Lobinski (pp. 1276-1283).
Immunoaffinity chromatography has been investigated for fractionation of serum into selenoalbumin and true selenoproteins. Among several albumin-depletion kits tested, a multiaffinity column specifically binding albumin and five other major serum proteins provided the best results. It extracted ca 95% of both albumin and selenoalbumin, which enabled interference-free determination of glutathione peroxidase, selenoprotein P, and selenoalbumin by size-exclusion chromatography combined with inductively coupled plasma mass spectrometry (SEC–ICPMS). The efficiency of the multiaffinity column did not vary over a period of 18 months. The purity of fractions separated by immunoaffinity LC was confirmed by elution-volume matching with standards in SEC–ICPMS and by selenopeptide mapping in capillary HPLC–ICPMS. Quantification of the selenium distribution among the different proteins in human serum from a control group and from a person on a selenium-rich diet revealed that 67% of the supplemented selenium was incorporated into albumin, 30% into glutathione peroxidase, and 3% into selenoprotein P.
Keywords: Immunoaffinity chromatography; Size-exclusion chromatography–ICPMS; Selenium-containing proteins; Selenoalbumin; Selenoproteins; Albumin depletion; Selenium speciation; Selenium distribution; Selenium-rich diet
Fractionation of selenium-containing proteins in serum by multiaffinity liquid chromatography before size-exclusion chromatography–ICPMS by Òscar Palacios; Jorge Ruiz Encinar; Dirk Schaumlöffel; Ryszard Lobinski (pp. 1276-1283).
Immunoaffinity chromatography has been investigated for fractionation of serum into selenoalbumin and true selenoproteins. Among several albumin-depletion kits tested, a multiaffinity column specifically binding albumin and five other major serum proteins provided the best results. It extracted ca 95% of both albumin and selenoalbumin, which enabled interference-free determination of glutathione peroxidase, selenoprotein P, and selenoalbumin by size-exclusion chromatography combined with inductively coupled plasma mass spectrometry (SEC–ICPMS). The efficiency of the multiaffinity column did not vary over a period of 18 months. The purity of fractions separated by immunoaffinity LC was confirmed by elution-volume matching with standards in SEC–ICPMS and by selenopeptide mapping in capillary HPLC–ICPMS. Quantification of the selenium distribution among the different proteins in human serum from a control group and from a person on a selenium-rich diet revealed that 67% of the supplemented selenium was incorporated into albumin, 30% into glutathione peroxidase, and 3% into selenoprotein P.
Keywords: Immunoaffinity chromatography; Size-exclusion chromatography–ICPMS; Selenium-containing proteins; Selenoalbumin; Selenoproteins; Albumin depletion; Selenium speciation; Selenium distribution; Selenium-rich diet
Direct detection of nitric oxide in human blood serum by use of 1,3,5,7-tetramethyl-8-(3′,4′-diaminophenyl)difluoroboradiaza-s-indacene with HPLC by Ke-Jing Huang; Hong Wang; Qi-Yun Zhang; Ming Ma; Jing-Fa Hu; Hua-Shan Zhang (pp. 1284-1290).
To study the relationship between amounts of nitric oxide (NO) in blood and the development of ischemic cardio-cerebrovascular diseases, trace NO in human blood serum has, for the first time, been determined by use of a 1,3,5,7-tetramethyl-8-(3′,4′-diaminophenyl)difluoroboradiaza-s-indacene (TMDABODIPY)-based HPLC method. The proposed method is simple, rapid, and efficient, owing to its high sensitivity and good selectivity for NO. TMDABODIPY and its NO derivative are separated to baseline in 4 min, with simple separation conditions, on a C18 column eluted with 50 mmol L−1 ethanolamine in methanol. The derivative is detected by fluorescence at an emission wavelength of 507 nm with excitation at 498 nm. The response is a linear function of concentration in the range 0.8–800 nmol L−1 NO. The detection limit can reach 2×10−11 mol L−1 (signal-to-noise ratio=3). The method has been used to detect NO in the serum of patients with five kinds of ischemic cardio-cerebrovascular disease and two diseases closely connected with ischemic cardio-cerebrovascular diseases. Recoveries of NO from spiked serum samples were between 96.58 and 105.71% and concentrations of NO observed in real samples were at 10−7 mol L−1 levels. Our studies indicate that the proposed TMDABODIPY-based HPLC technique can be developed into a sensitive and new method for clinical assay and pathology research.
Keywords: Nitric oxide; Serum; 1,3,5,7-Tetramethyl-8-(3′,4′-diaminophenyl)difluoroboradiaza-s-indacene; HPLC; Ischemic cardio-cerebrovascular diseases
Direct detection of nitric oxide in human blood serum by use of 1,3,5,7-tetramethyl-8-(3′,4′-diaminophenyl)difluoroboradiaza-s-indacene with HPLC by Ke-Jing Huang; Hong Wang; Qi-Yun Zhang; Ming Ma; Jing-Fa Hu; Hua-Shan Zhang (pp. 1284-1290).
To study the relationship between amounts of nitric oxide (NO) in blood and the development of ischemic cardio-cerebrovascular diseases, trace NO in human blood serum has, for the first time, been determined by use of a 1,3,5,7-tetramethyl-8-(3′,4′-diaminophenyl)difluoroboradiaza-s-indacene (TMDABODIPY)-based HPLC method. The proposed method is simple, rapid, and efficient, owing to its high sensitivity and good selectivity for NO. TMDABODIPY and its NO derivative are separated to baseline in 4 min, with simple separation conditions, on a C18 column eluted with 50 mmol L−1 ethanolamine in methanol. The derivative is detected by fluorescence at an emission wavelength of 507 nm with excitation at 498 nm. The response is a linear function of concentration in the range 0.8–800 nmol L−1 NO. The detection limit can reach 2×10−11 mol L−1 (signal-to-noise ratio=3). The method has been used to detect NO in the serum of patients with five kinds of ischemic cardio-cerebrovascular disease and two diseases closely connected with ischemic cardio-cerebrovascular diseases. Recoveries of NO from spiked serum samples were between 96.58 and 105.71% and concentrations of NO observed in real samples were at 10−7 mol L−1 levels. Our studies indicate that the proposed TMDABODIPY-based HPLC technique can be developed into a sensitive and new method for clinical assay and pathology research.
Keywords: Nitric oxide; Serum; 1,3,5,7-Tetramethyl-8-(3′,4′-diaminophenyl)difluoroboradiaza-s-indacene; HPLC; Ischemic cardio-cerebrovascular diseases
Solvent effects in the preparation of molecularly imprinted polymers for melatonin using N-propionyl-5-methoxytryptamine as the pseudo template by Makoto Nomachi; Takuya Kubo; Ken Hosoya; Kunimitsu Kaya (pp. 1291-1296).
To clarify the role of diluents in the preparation of molecularly imprinted polymers utilizing only hydrogen bonding, we investigated the effects of diluents by using different solvents. Melatonin (N-acetyl-5-methoxytryptamine), an amide bond and indole ring-containing hormone was chosen as the target molecule. N-Propionyl-5-methoxytryptamine was used as the pseudo template, methacrylic acid as the functional monomer, and solvents were used as diluents. Interactions between the template, the functional monomer, melatonin, and the solvents, were observed by 1H NMR spectroscopy. The polymers were evaluated by high-performance liquid chromatography. The results suggest the hydrogen bonding-acceptor capacity of the solvent is the most important factor in the preparation of molecularly imprinted polymers for hydrogen bonding-donating molecules. Hydrogen bonding between the template, the functional monomer, and solvent can be estimated from the chemical shifts in 1H NMR spectra of those molecules in the solvent.
Keywords: Molecularly imprinted polymer; Selective recognition; Hydrogen bonding; Solvent effect; Liquid chromatography
Solvent effects in the preparation of molecularly imprinted polymers for melatonin using N-propionyl-5-methoxytryptamine as the pseudo template by Makoto Nomachi; Takuya Kubo; Ken Hosoya; Kunimitsu Kaya (pp. 1291-1296).
To clarify the role of diluents in the preparation of molecularly imprinted polymers utilizing only hydrogen bonding, we investigated the effects of diluents by using different solvents. Melatonin (N-acetyl-5-methoxytryptamine), an amide bond and indole ring-containing hormone was chosen as the target molecule. N-Propionyl-5-methoxytryptamine was used as the pseudo template, methacrylic acid as the functional monomer, and solvents were used as diluents. Interactions between the template, the functional monomer, melatonin, and the solvents, were observed by 1H NMR spectroscopy. The polymers were evaluated by high-performance liquid chromatography. The results suggest the hydrogen bonding-acceptor capacity of the solvent is the most important factor in the preparation of molecularly imprinted polymers for hydrogen bonding-donating molecules. Hydrogen bonding between the template, the functional monomer, and solvent can be estimated from the chemical shifts in 1H NMR spectra of those molecules in the solvent.
Keywords: Molecularly imprinted polymer; Selective recognition; Hydrogen bonding; Solvent effect; Liquid chromatography
Fluorometric determination of sugars using fluorescein-labeled concanavalin A–glycogen conjugates by Katsuhiko Sato; Jun-ichi Anzai (pp. 1297-1301).
The fluorescence of fluoresceinisothiocyanate-labeled concanavalin A (FITC-Con A) was quenched by forming an FITC-Con A–glycogen conjugate and dequenched upon addition of sugars to the conjugate solution due to disaggregation of the conjugate. However, fluorescence quenching was barely observed upon formation of FITC-Con A–dextran conjugate. The sugar-induced fluorescence response of the FITC-Con A–glycogen conjugate depended significantly on the type of sugar: methylated α-D-glucose and α-D-mannose both induced high and rapid responses, while the responses to D-mannose and D-glucose were moderate. In contrast, no response was observed in the presence of D-galactose due to a lack of affinity to Con A. Thus, it is apparent that D-glucose and other sugars can be detected via the fluorescence of the FITC-Con A–glycogen conjugate.
Keywords: Concanavalin A; Glycogen; Fluorescence; D-glucose detection; Con A–glycogen conjugate
Fluorometric determination of sugars using fluorescein-labeled concanavalin A–glycogen conjugates by Katsuhiko Sato; Jun-ichi Anzai (pp. 1297-1301).
The fluorescence of fluoresceinisothiocyanate-labeled concanavalin A (FITC-Con A) was quenched by forming an FITC-Con A–glycogen conjugate and dequenched upon addition of sugars to the conjugate solution due to disaggregation of the conjugate. However, fluorescence quenching was barely observed upon formation of FITC-Con A–dextran conjugate. The sugar-induced fluorescence response of the FITC-Con A–glycogen conjugate depended significantly on the type of sugar: methylated α-D-glucose and α-D-mannose both induced high and rapid responses, while the responses to D-mannose and D-glucose were moderate. In contrast, no response was observed in the presence of D-galactose due to a lack of affinity to Con A. Thus, it is apparent that D-glucose and other sugars can be detected via the fluorescence of the FITC-Con A–glycogen conjugate.
Keywords: Concanavalin A; Glycogen; Fluorescence; D-glucose detection; Con A–glycogen conjugate
Application of a xenon arc lamp as a light source for evaporative light scattering detection by Karen Gaudin; Arlette Baillet; Pierre Chaminade (pp. 1302-1307).
The standard tungsten-halogen light source used in a commercial evaporative light scattering detector (ELSD) was replaced with a 180 W xenon arc lamp. The xenon arc lamp possesses a broader spectrum in the UV region than the halogen source. The influence of the UV transmittance of five selected solvents was studied with a size-exclusion chromatography column. This solvent parameter was not observed to influence the ELSD response between the two light source settings. With the solvents studied, better sensitivity was obtained with the xenon arc lamp than the halogen lamp. This high-energy source was applied to ceramide III analysis with an octadecyl-grafted silica column and methanol:tetrahydrofuran 97:3 as the mobile phase, and the sensitivity of the quantification of ceramide III increased 16-fold for injected amounts of 14∼140 ng. The molecular species in a sample of naturally occurring ceramides was analyzed using two C18 columns at 40 °C and gradient elution from 100% acetonitrile to 100% isopropanol in 30 min. The increased ELSD sensitivity achieved when using the xenon arc lamp allowed both the minor and major ceramide species to be observed, in contrast to the results achieved when the halogen lamp was used, where the increased photomultiplier voltage needed to observed the signals from the minor species caused the signals from the major ceramide species to occur above the detector response window.
Keywords: Evaporative light scattering detection; Triglyceride; Ceramide; Xenon arc lamp
Application of a xenon arc lamp as a light source for evaporative light scattering detection by Karen Gaudin; Arlette Baillet; Pierre Chaminade (pp. 1302-1307).
The standard tungsten-halogen light source used in a commercial evaporative light scattering detector (ELSD) was replaced with a 180 W xenon arc lamp. The xenon arc lamp possesses a broader spectrum in the UV region than the halogen source. The influence of the UV transmittance of five selected solvents was studied with a size-exclusion chromatography column. This solvent parameter was not observed to influence the ELSD response between the two light source settings. With the solvents studied, better sensitivity was obtained with the xenon arc lamp than the halogen lamp. This high-energy source was applied to ceramide III analysis with an octadecyl-grafted silica column and methanol:tetrahydrofuran 97:3 as the mobile phase, and the sensitivity of the quantification of ceramide III increased 16-fold for injected amounts of 14∼140 ng. The molecular species in a sample of naturally occurring ceramides was analyzed using two C18 columns at 40 °C and gradient elution from 100% acetonitrile to 100% isopropanol in 30 min. The increased ELSD sensitivity achieved when using the xenon arc lamp allowed both the minor and major ceramide species to be observed, in contrast to the results achieved when the halogen lamp was used, where the increased photomultiplier voltage needed to observed the signals from the minor species caused the signals from the major ceramide species to occur above the detector response window.
Keywords: Evaporative light scattering detection; Triglyceride; Ceramide; Xenon arc lamp
Determination of dopamine in rat striatum by microdialysis and high-performance liquid chromatography with electrochemical detection on a functionalized multi-wall carbon nanotube electrode by Li Lin; Peihong Qiu; Lizhu Yang; Xuni Cao; Litong Jin (pp. 1308-1313).
High performance liquid chromatography coupled with microdialysis sampling and electrochemical detection (HPLC–ECD) has been used to determine dopamine (DA). In the HPLC–ECD a multi-wall carbon nanotube electrode chemically modified with carboxyl groups (MWNT-COOH CME) was used as the working electrode for determination of DA. The results indicated that the MWNT-COOH CME enabled efficient electrocatalytic oxidation of DA with relatively high sensitivity and stability and long life. Peak currents for dopamine were linearly dependent on concentration in the range 5.0×10−9 to 5.0×10−5 mol L−1 and the calculated detection limit (S/N=3) was 2.5×10−9 mol L−1. The method had been successfully used to measure dopamine in rat striatal microdialysate. To study the physiological effect of nitric oxide (NO) on striatal release of DA, 0.5 mmol L−1 sodium nitroprusside (SNP) was a continuously perfused into rat striatum. This resulted in a 46% increase in DA basal level.
Keywords: Multi-wall carbon nanotubes; Chemically modified electrode; High-performance liquid chromatography; Dopamine; Microdialysis
Determination of dopamine in rat striatum by microdialysis and high-performance liquid chromatography with electrochemical detection on a functionalized multi-wall carbon nanotube electrode by Li Lin; Peihong Qiu; Lizhu Yang; Xuni Cao; Litong Jin (pp. 1308-1313).
High performance liquid chromatography coupled with microdialysis sampling and electrochemical detection (HPLC–ECD) has been used to determine dopamine (DA). In the HPLC–ECD a multi-wall carbon nanotube electrode chemically modified with carboxyl groups (MWNT-COOH CME) was used as the working electrode for determination of DA. The results indicated that the MWNT-COOH CME enabled efficient electrocatalytic oxidation of DA with relatively high sensitivity and stability and long life. Peak currents for dopamine were linearly dependent on concentration in the range 5.0×10−9 to 5.0×10−5 mol L−1 and the calculated detection limit (S/N=3) was 2.5×10−9 mol L−1. The method had been successfully used to measure dopamine in rat striatal microdialysate. To study the physiological effect of nitric oxide (NO) on striatal release of DA, 0.5 mmol L−1 sodium nitroprusside (SNP) was a continuously perfused into rat striatum. This resulted in a 46% increase in DA basal level.
Keywords: Multi-wall carbon nanotubes; Chemically modified electrode; High-performance liquid chromatography; Dopamine; Microdialysis
Flow-injection enhanced chemiluminescence method for determination of ciprofloxacin in pharmaceutical preparations and biological fluids by Han-Wen Sun; Li-Qing Li; Xue-Yan Chen (pp. 1314-1319).
A novel rapid and sensitive analytical method, enhanced chemiluminescence with flow-injection sampling, is described for determination of ciprofloxacin. The method is based on the chemiluminescence reaction of the potassium permanganate–sodium thiosulfate–ciprofloxacin system. An enhanced chemiluminescence reaction was developed, and optimum conditions for CL emission were investigated. The chemiluminescence intensity was linearly dependent on ciprofloxacin concentration in the range 1.0×10−8–1.0×10−5 g mL−1. The detection limit was 4×10−9 g mL−1. The relative standard deviation was 1.8% for eleven measurements of 2.0×10−7 g mL−1 ciprofloxacin standard solution. The new method enables simple, sensitive, and rapid determination of ciprofloxacin and has been successfully used for determination of ciprofloxacin in biological fluids and in ciprofloxacin hydrochloride tablet and injection.
Keywords: Ciprofloxacin; Chemiluminescence analysis; Flow injection; Pharmaceutical analysis; Biological fluids
Flow-injection enhanced chemiluminescence method for determination of ciprofloxacin in pharmaceutical preparations and biological fluids by Han-Wen Sun; Li-Qing Li; Xue-Yan Chen (pp. 1314-1319).
A novel rapid and sensitive analytical method, enhanced chemiluminescence with flow-injection sampling, is described for determination of ciprofloxacin. The method is based on the chemiluminescence reaction of the potassium permanganate–sodium thiosulfate–ciprofloxacin system. An enhanced chemiluminescence reaction was developed, and optimum conditions for CL emission were investigated. The chemiluminescence intensity was linearly dependent on ciprofloxacin concentration in the range 1.0×10−8–1.0×10−5 g mL−1. The detection limit was 4×10−9 g mL−1. The relative standard deviation was 1.8% for eleven measurements of 2.0×10−7 g mL−1 ciprofloxacin standard solution. The new method enables simple, sensitive, and rapid determination of ciprofloxacin and has been successfully used for determination of ciprofloxacin in biological fluids and in ciprofloxacin hydrochloride tablet and injection.
Keywords: Ciprofloxacin; Chemiluminescence analysis; Flow injection; Pharmaceutical analysis; Biological fluids
Deposition measurement of particulate matter in connection with corrosion studies by Martin Ferm; John Watt; Samantha O’Hanlon; Franco De Santis; Costas Varotsos (pp. 1320-1330).
A new passive particle collector (inert surrogate surface) that collects particles from all directions has been developed. It was used to measure particle deposition at 35 test sites as part of a project that examined corrosion of materials in order that variation in particulate material could be used in development of dose–response functions in a modern multi-pollutant environment. The project, MULTI-ASSESS, was funded by the EU to examine the effects of air pollution on cultural heritage. Passive samplers were mounted rain-protected, and both in wind-protected and wind-exposed positions, to match the exposure of the samples for corrosion studies. The particle mass and its chemical content (nitrate, ammonium, sulfate, calcium, sodium, chloride, magnesium and potassium) were analysed. The loss of light reflectance on the surrogate surface was also measured. Very little ammonium and potassium was found, and one or more anions are missing in the ion balance. There were many strong correlations between the analysed species. The mass of analysed water-soluble ions was fairly constant at 24% of the total mass. The particle mass deposited to the samplers in the wind-protected position was about 25% of the particles deposited to an openly exposed sampler. The Cl−/Na+ ratios indicate a reaction between HNO3 and NaCl. The deposited nitrate flux corresponds to the missing chloride. The Ca2+ deposition equals the $$ ext{SO}_4^{2 - }$$ deposition and the anion deficiency. The $$ ext{SO}_4^{2 - }$$ deposition most likely originates from SO2 that has reacted with basic calcium-containing particles either before or after they were deposited. The particle depositions at the urban sites were much higher than in nearby rural sites. The deposited mass correlated surprisingly well with the PM10 concentration, except at sites very close to traffic.
Keywords: Corrosion; Cultural heritage; Sodium chloride; Passive sampler; Surrogate surface; Soiling; Calcium
Deposition measurement of particulate matter in connection with corrosion studies by Martin Ferm; John Watt; Samantha O’Hanlon; Franco De Santis; Costas Varotsos (pp. 1320-1330).
A new passive particle collector (inert surrogate surface) that collects particles from all directions has been developed. It was used to measure particle deposition at 35 test sites as part of a project that examined corrosion of materials in order that variation in particulate material could be used in development of dose–response functions in a modern multi-pollutant environment. The project, MULTI-ASSESS, was funded by the EU to examine the effects of air pollution on cultural heritage. Passive samplers were mounted rain-protected, and both in wind-protected and wind-exposed positions, to match the exposure of the samples for corrosion studies. The particle mass and its chemical content (nitrate, ammonium, sulfate, calcium, sodium, chloride, magnesium and potassium) were analysed. The loss of light reflectance on the surrogate surface was also measured. Very little ammonium and potassium was found, and one or more anions are missing in the ion balance. There were many strong correlations between the analysed species. The mass of analysed water-soluble ions was fairly constant at 24% of the total mass. The particle mass deposited to the samplers in the wind-protected position was about 25% of the particles deposited to an openly exposed sampler. The Cl−/Na+ ratios indicate a reaction between HNO3 and NaCl. The deposited nitrate flux corresponds to the missing chloride. The Ca2+ deposition equals the % MathType!Translator!2!1!AMS LaTeX.tdl!TeX -- AMS-LaTeX!% MathType!MTEF!2!1!+-% feaaeaart1ev0aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbbjxAHX% garmWu51MyVXgatuuDJXwAK1uy0HwmaeHbfv3ySLgzG0uy0Hgip5wz% aebbnrfifHhDYfgasaacH8qrps0lbbf9q8WrFfeuY-Hhbbf9v8qqaq% Fr0xc9pk0xbba9q8WqFfea0-yr0RYxir-Jbba9q8aq0-yq-He9q8qq% Q8frFve9Fve9Ff0dmeaabaqaciGacaGaaeqabaWaaeWaeaaakeaaca% qGtbGaae4tamaaDaaaleaacaaI0aaabaGaaGOmaiabgkHiTaaaaaa!3BCC! $$ ext{SO}_4^{2 - }$$ deposition and the anion deficiency. The % MathType!Translator!2!1!AMS LaTeX.tdl!TeX -- AMS-LaTeX!% MathType!MTEF!2!1!+-% feaaeaart1ev0aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbbjxAHX% garmWu51MyVXgatuuDJXwAK1uy0HwmaeHbfv3ySLgzG0uy0Hgip5wz% aebbnrfifHhDYfgasaacH8qrps0lbbf9q8WrFfeuY-Hhbbf9v8qqaq% Fr0xc9pk0xbba9q8WqFfea0-yr0RYxir-Jbba9q8aq0-yq-He9q8qq% Q8frFve9Fve9Ff0dmeaabaqaciGacaGaaeqabaWaaeWaeaaakeaaca% qGtbGaae4tamaaDaaaleaacaaI0aaabaGaaGOmaiabgkHiTaaaaaa!3BCC! $$ ext{SO}_4^{2 - }$$ deposition most likely originates from SO2 that has reacted with basic calcium-containing particles either before or after they were deposited. The particle depositions at the urban sites were much higher than in nearby rural sites. The deposited mass correlated surprisingly well with the PM10 concentration, except at sites very close to traffic.
Keywords: Corrosion; Cultural heritage; Sodium chloride; Passive sampler; Surrogate surface; Soiling; Calcium
Accelerated extraction for determination of polycyclic aromatic hydrocarbons in marine biota by J. Sanz-Landaluze; L. Bartolome; O. Zuloaga; L. González; C. Dietz; C. Cámara (pp. 1331-1340).
A rapid and simple method is proposed for determination of polycyclic aromatic hydrocarbons (PAH) in complex matrices such as marine biota. The method uses sonication, by means of an ultrasonic probe, as a new tool for assisted extraction, coupled with reversed-phase liquid chromatography (RP-LC) with fluorescence detection (FL) for determination of 16 US EPA priority PAH. Separation and detection of the 16 PAH were complete in 45 min by RP-LC with a C18 column and acetonitrile–water gradient elution. Multivariate optimisation of the variables affecting extraction (ultrasound radiation amplitude, sonication time, and temperature of the water-bath in which the extraction cell was placed) was conducted. The accuracy of the method was determined by analysis of a certified reference material and comparison of the results obtained with those from another method (microwave-assisted extraction and GC–MS). The new technique avoids the main problems encountered in the determination of PAH in complex matrices such as marine biota, and no clean-up step is necessary. The method was applied to determination of PAH in estuarine biota samples from the Urdaibai estuary (Biscay, Spain).
Keywords: PAH; Extraction; Ultrasonic probe; Biota samples
Accelerated extraction for determination of polycyclic aromatic hydrocarbons in marine biota by J. Sanz-Landaluze; L. Bartolome; O. Zuloaga; L. González; C. Dietz; C. Cámara (pp. 1331-1340).
A rapid and simple method is proposed for determination of polycyclic aromatic hydrocarbons (PAH) in complex matrices such as marine biota. The method uses sonication, by means of an ultrasonic probe, as a new tool for assisted extraction, coupled with reversed-phase liquid chromatography (RP-LC) with fluorescence detection (FL) for determination of 16 US EPA priority PAH. Separation and detection of the 16 PAH were complete in 45 min by RP-LC with a C18 column and acetonitrile–water gradient elution. Multivariate optimisation of the variables affecting extraction (ultrasound radiation amplitude, sonication time, and temperature of the water-bath in which the extraction cell was placed) was conducted. The accuracy of the method was determined by analysis of a certified reference material and comparison of the results obtained with those from another method (microwave-assisted extraction and GC–MS). The new technique avoids the main problems encountered in the determination of PAH in complex matrices such as marine biota, and no clean-up step is necessary. The method was applied to determination of PAH in estuarine biota samples from the Urdaibai estuary (Biscay, Spain).
Keywords: PAH; Extraction; Ultrasonic probe; Biota samples
Quality-control materials in the USDA National Food and Nutrient Analysis Program (NFNAP) by Katherine M. Phillips; Kristine Y. Patterson; Amy S. Rasor; Jacob Exler; David B. Haytowitz; Joanne M. Holden; Pamela R. Pehrsson (pp. 1341-1355).
The US Department of Agriculture (USDA) Nutrient Data Laboratory (NDL) develops and maintains the USDA National Nutrient Databank System (NDBS). Data are released from the NDBS for scientific and public use through the USDA National Nutrient Database for Standard Reference (SR) ( http://www.ars.usda.gov/ba/bhnrc/ndl ). In 1997 the NDL initiated the National Food and Nutrient Analysis Program (NFNAP) to update and expand its food-composition data. The program included: 1) nationwide probability-based sampling of foods; 2) central processing and archiving of food samples; 3) analysis of food components at commercial, government, and university laboratories; 4) incorporation of new analytical data into the NDBS; and 5) dissemination of these data to the scientific community. A key feature and strength of the NFNAP was a rigorous quality-control program that enabled independent verification of the accuracy and precision of analytical results. Custom-made food-control composites and/or commercially available certified reference materials were sent to the laboratories, blinded, with the samples. Data for these materials were essential to ongoing monitoring of analytical work, to identify and resolve suspected analytical problems, to ensure the accuracy and precision of results for the NFNAP food samples.
Keywords: Quality control (QC); Reference materials; Food analysis; Food composition
Quality-control materials in the USDA National Food and Nutrient Analysis Program (NFNAP) by Katherine M. Phillips; Kristine Y. Patterson; Amy S. Rasor; Jacob Exler; David B. Haytowitz; Joanne M. Holden; Pamela R. Pehrsson (pp. 1341-1355).
The US Department of Agriculture (USDA) Nutrient Data Laboratory (NDL) develops and maintains the USDA National Nutrient Databank System (NDBS). Data are released from the NDBS for scientific and public use through the USDA National Nutrient Database for Standard Reference (SR) ( http://www.ars.usda.gov/ba/bhnrc/ndl ). In 1997 the NDL initiated the National Food and Nutrient Analysis Program (NFNAP) to update and expand its food-composition data. The program included: 1) nationwide probability-based sampling of foods; 2) central processing and archiving of food samples; 3) analysis of food components at commercial, government, and university laboratories; 4) incorporation of new analytical data into the NDBS; and 5) dissemination of these data to the scientific community. A key feature and strength of the NFNAP was a rigorous quality-control program that enabled independent verification of the accuracy and precision of analytical results. Custom-made food-control composites and/or commercially available certified reference materials were sent to the laboratories, blinded, with the samples. Data for these materials were essential to ongoing monitoring of analytical work, to identify and resolve suspected analytical problems, to ensure the accuracy and precision of results for the NFNAP food samples.
Keywords: Quality control (QC); Reference materials; Food analysis; Food composition
Anatase—a pigment in ancient artwork or a modern usurper? by Howell G. M. Edwards; Nik F. Nik Hassan; Paul S. Middleton (pp. 1356-1365).
Fragments of wall-paintings from Roman villas in Easton Maudit, which date from ca 150 AD have been studied by Raman spectroscopy. An intact ancient Roman paint pot discovered in the remains of a villa in Castor, Cambridgeshire, still containing a mixture of white and red pigment was also analysed and the pigments identified as haematite and anatase. The discovery of anatase in the intact artist’s paint pot, particularly, and also on fragments of broken paint pots from the Easton Maudit villa site, is a unique contribution to current knowledge of ancient European pigment history, because the presence of this mineral has not hitherto been recognised fully in an ancient artist’s palette. The relative spectral response of anatase and haematite in the Raman data is compared with that of anatase and other red pigments such as minium, cinnabar, and litharge.
Keywords: Roman villa; Paint pot; Raman spectroscopy; Anatase
Anatase—a pigment in ancient artwork or a modern usurper? by Howell G. M. Edwards; Nik F. Nik Hassan; Paul S. Middleton (pp. 1356-1365).
Fragments of wall-paintings from Roman villas in Easton Maudit, which date from ca 150 AD have been studied by Raman spectroscopy. An intact ancient Roman paint pot discovered in the remains of a villa in Castor, Cambridgeshire, still containing a mixture of white and red pigment was also analysed and the pigments identified as haematite and anatase. The discovery of anatase in the intact artist’s paint pot, particularly, and also on fragments of broken paint pots from the Easton Maudit villa site, is a unique contribution to current knowledge of ancient European pigment history, because the presence of this mineral has not hitherto been recognised fully in an ancient artist’s palette. The relative spectral response of anatase and haematite in the Raman data is compared with that of anatase and other red pigments such as minium, cinnabar, and litharge.
Keywords: Roman villa; Paint pot; Raman spectroscopy; Anatase
Simultaneous determination of 405 pesticide residues in grain by accelerated solvent extraction then gas chromatography-mass spectrometry or liquid chromatography-tandem mass spectrometry by Guo-Fang Pang; Yong-Ming Liu; Chun-Lin Fan; Jin-Jie Zhang; Yan-Zhong Cao; Xue-Min Li; Zeng-Yin Li; Yan-Ping Wu; Tong-Tong Guo (pp. 1366-1408).
A new method has been established for simultaneous determination of 405 pesticide residues in grain, using accelerated solvent extraction (ASE), solid-phase extraction (SPE), and GC-MS and LC-MS-MS. The method was based on appraisal of the GC-MS and LC-MS-MS characteristics of 660 pesticides, their efficiency of extraction from grain, and their purification. Samples of grain (10 g) were mixed with Celite 545 (10 g) and the mixture was placed in a 34-mL cell of an accelerated solvent extractor and extracted with acetonitrile in the static state for 3 min with two cycles at 1,500 psig and at 80°C. For the 362 pesticides determined by GC-MS, half of the extracts were cleaned with an Envi-18 cartridge and then further cleaned with Envi-Carb and Sep-Pak NH2 cartridges in series. The pesticides were eluted with acetonitrile-toluene, 3:1, and the eluates were concentrated and used for analysis after being exchanged with hexane twice. For the 43 pesticides determined by LC-MS-MS the other half of the extracts were cleaned with Sep-Pak Alumina N cartridge and further cleaned with Envi-Carb and Sep-Pak NH2 cartridges. Pesticides were eluted with acetonitrile-toluene, 3:1. After evaporation to dryness the eluates were diluted with acetonitrile-water, 3:2, and used for analysis. In the linear range of each pesticide the linear correlation coefficient r was equal to or greater than 0.956 and 94% of linear correlation coefficients were greater than 0.990. At low, medium, and high fortification levels, at the limit of detection (LOD), twice the LOD and ten times LOD, respectively, recoveries ranged from 42 to 132%; for 382 pesticides, or 94.32%, recovery was from 60 to 120%. The relative standard deviation (RSD) was always below 38% and was below 30% for 391 pesticides, or 96.54%. The LOD was 0.0005–0.3000 mg kg−1. The proposed method is suitable for determination of 405 pesticide residues in grain such as maize, wheat, oat, rice, and barley, etc.
Keywords: Analysis of residues of 405 pesticides; Grain; ASE; GC-MS; LC-MS-MS
Simultaneous determination of 405 pesticide residues in grain by accelerated solvent extraction then gas chromatography-mass spectrometry or liquid chromatography-tandem mass spectrometry by Guo-Fang Pang; Yong-Ming Liu; Chun-Lin Fan; Jin-Jie Zhang; Yan-Zhong Cao; Xue-Min Li; Zeng-Yin Li; Yan-Ping Wu; Tong-Tong Guo (pp. 1366-1408).
A new method has been established for simultaneous determination of 405 pesticide residues in grain, using accelerated solvent extraction (ASE), solid-phase extraction (SPE), and GC-MS and LC-MS-MS. The method was based on appraisal of the GC-MS and LC-MS-MS characteristics of 660 pesticides, their efficiency of extraction from grain, and their purification. Samples of grain (10 g) were mixed with Celite 545 (10 g) and the mixture was placed in a 34-mL cell of an accelerated solvent extractor and extracted with acetonitrile in the static state for 3 min with two cycles at 1,500 psig and at 80°C. For the 362 pesticides determined by GC-MS, half of the extracts were cleaned with an Envi-18 cartridge and then further cleaned with Envi-Carb and Sep-Pak NH2 cartridges in series. The pesticides were eluted with acetonitrile-toluene, 3:1, and the eluates were concentrated and used for analysis after being exchanged with hexane twice. For the 43 pesticides determined by LC-MS-MS the other half of the extracts were cleaned with Sep-Pak Alumina N cartridge and further cleaned with Envi-Carb and Sep-Pak NH2 cartridges. Pesticides were eluted with acetonitrile-toluene, 3:1. After evaporation to dryness the eluates were diluted with acetonitrile-water, 3:2, and used for analysis. In the linear range of each pesticide the linear correlation coefficient r was equal to or greater than 0.956 and 94% of linear correlation coefficients were greater than 0.990. At low, medium, and high fortification levels, at the limit of detection (LOD), twice the LOD and ten times LOD, respectively, recoveries ranged from 42 to 132%; for 382 pesticides, or 94.32%, recovery was from 60 to 120%. The relative standard deviation (RSD) was always below 38% and was below 30% for 391 pesticides, or 96.54%. The LOD was 0.0005–0.3000 mg kg−1. The proposed method is suitable for determination of 405 pesticide residues in grain such as maize, wheat, oat, rice, and barley, etc.
Keywords: Analysis of residues of 405 pesticides; Grain; ASE; GC-MS; LC-MS-MS
Characterisation of ethoxylated fatty chains of anionic surfactants and determination of residual ethoxylated fatty alcohols by Julien Morvan; Magali Saluden; Valérie Agasse; Florence Barbot; Pascal Cardinael; Jean-Philippe Bouillon; Gautier Decock (pp. 1409-1415).
Bachus et al. [1] recently described a new derivatisation method using 2-furoyl chloride for the characterisation of mixtures of polyethoxylated alcohols and their corresponding sulfates. This paper deals with the control of the derivatisation steps; hydrolysis and extraction conditions were optimised. The method is extended to the characterisation of alkyl sulfosuccinates, alkyl sulfoacetates and alkyl phosphates and to the analysis of residual polyethoxylated alcohols in surfactants. Extraction of non-ionic compounds using solid-phase extraction cartridges was performed before derivatisation. Residual amounts of alcohol were determined in five commercial anionic surfactants. Moreover, direct derivatisation without preliminary SPE in the same anionic surfactants proved to be efficient for dry samples.
Keywords: 2-Furoyl chloride; Alkyl sulfates; Alkyl sulfosuccinates; Alkyl sulfoacetates; HPLC-UV; SPE
Characterisation of ethoxylated fatty chains of anionic surfactants and determination of residual ethoxylated fatty alcohols by Julien Morvan; Magali Saluden; Valérie Agasse; Florence Barbot; Pascal Cardinael; Jean-Philippe Bouillon; Gautier Decock (pp. 1409-1415).
Bachus et al. [1] recently described a new derivatisation method using 2-furoyl chloride for the characterisation of mixtures of polyethoxylated alcohols and their corresponding sulfates. This paper deals with the control of the derivatisation steps; hydrolysis and extraction conditions were optimised. The method is extended to the characterisation of alkyl sulfosuccinates, alkyl sulfoacetates and alkyl phosphates and to the analysis of residual polyethoxylated alcohols in surfactants. Extraction of non-ionic compounds using solid-phase extraction cartridges was performed before derivatisation. Residual amounts of alcohol were determined in five commercial anionic surfactants. Moreover, direct derivatisation without preliminary SPE in the same anionic surfactants proved to be efficient for dry samples.
Keywords: 2-Furoyl chloride; Alkyl sulfates; Alkyl sulfosuccinates; Alkyl sulfoacetates; HPLC-UV; SPE
Online analysis of europium and gadolinium species complexed or uncomplexed with humic acid by capillary electrophoresis–inductively coupled plasma mass spectrometry by Ralf Kautenburger; Karsten Nowotka; Horst Philipp Beck (pp. 1416-1422).
Detailed information on the geochemical behavior of radioactive and toxic metal ions under environmental conditions (in geological matrices and aquifer systems) is needed in order to assess the long-term safety of waste repositories. This includes knowledge of the mechanisms of relevant geochemical reactions, as well as associated thermodynamic and kinetic data. Several previous studies have shown that humic acid can play an important role in the immobilization or mobilization of metal ions due to complexation and colloid formation. In our project we investigate the complexation behavior of (purified Aldrich) humic acid and its influence on the migration of the lanthanides europium and gadolinium (homologs of the actinides americium and curium) in the ternary system consisting of these heavy metals, humic acid and kaolinite (KGa-1b) under almost natural conditions. Capillary electrophoresis (CE, Beckman Coulter P/ACE MDQ), with its excellent separation performance, was hyphenated with a homemade interface to inductively coupled plasma mass spectrometry (ICP–MS, VG Elemental PlasmaQuad 3) giving a system that is highly sensitive to the rare-earth element species of europium and gadolinium with humic acid. The humic acid used was also halogenated with iodine, which acted as an ICP–MS marker. To couple CE to ICP–MS, a fused silica CE capillary was flexibly fitted into a MicroMist 50 μl nebulizer with a Cinnabar cyclonic spray chamber in the external homemade interface. The chamber was chilled to a temperature of 4 °C to optimize the sensitivity. 200 ppb of cesium were added to the CE separation buffer so that the capillary flow could be observed. A make-up fluid including 4 ppb Ho as an internal standard was combined with the flow from the capillary within the interface in order to get a fluid throughput high enough to maintain continuous nebulization. Very low detection limits were achieved: 125 ppt for 153Eu and 250 ppt for 158Gd. Using this optimized CE–ICP–MS coupling system it was possible to quantify metal concentrations from the detection limit up to approximately 1 ppm (the linear range). This set-up was used to separate metal/humic acid-species in a 100 mM acetic acid/10 mM acetate buffer system. Using humic acid as the complexing ligand, uncomplexed metal ion species could be separated from metal–humate complexes on a time-resolved scale.
Keywords: CE–ICP–MS; Hyphenation; Radionuclides; Humic acid; Complexation
Online analysis of europium and gadolinium species complexed or uncomplexed with humic acid by capillary electrophoresis–inductively coupled plasma mass spectrometry by Ralf Kautenburger; Karsten Nowotka; Horst Philipp Beck (pp. 1416-1422).
Detailed information on the geochemical behavior of radioactive and toxic metal ions under environmental conditions (in geological matrices and aquifer systems) is needed in order to assess the long-term safety of waste repositories. This includes knowledge of the mechanisms of relevant geochemical reactions, as well as associated thermodynamic and kinetic data. Several previous studies have shown that humic acid can play an important role in the immobilization or mobilization of metal ions due to complexation and colloid formation. In our project we investigate the complexation behavior of (purified Aldrich) humic acid and its influence on the migration of the lanthanides europium and gadolinium (homologs of the actinides americium and curium) in the ternary system consisting of these heavy metals, humic acid and kaolinite (KGa-1b) under almost natural conditions. Capillary electrophoresis (CE, Beckman Coulter P/ACE MDQ), with its excellent separation performance, was hyphenated with a homemade interface to inductively coupled plasma mass spectrometry (ICP–MS, VG Elemental PlasmaQuad 3) giving a system that is highly sensitive to the rare-earth element species of europium and gadolinium with humic acid. The humic acid used was also halogenated with iodine, which acted as an ICP–MS marker. To couple CE to ICP–MS, a fused silica CE capillary was flexibly fitted into a MicroMist 50 μl nebulizer with a Cinnabar cyclonic spray chamber in the external homemade interface. The chamber was chilled to a temperature of 4 °C to optimize the sensitivity. 200 ppb of cesium were added to the CE separation buffer so that the capillary flow could be observed. A make-up fluid including 4 ppb Ho as an internal standard was combined with the flow from the capillary within the interface in order to get a fluid throughput high enough to maintain continuous nebulization. Very low detection limits were achieved: 125 ppt for 153Eu and 250 ppt for 158Gd. Using this optimized CE–ICP–MS coupling system it was possible to quantify metal concentrations from the detection limit up to approximately 1 ppm (the linear range). This set-up was used to separate metal/humic acid-species in a 100 mM acetic acid/10 mM acetate buffer system. Using humic acid as the complexing ligand, uncomplexed metal ion species could be separated from metal–humate complexes on a time-resolved scale.
Keywords: CE–ICP–MS; Hyphenation; Radionuclides; Humic acid; Complexation
Determination of Etofenprox in environmental samples by HPLC after anionic surfactant micelle-mediated extraction (coacervation extraction) by Guifang Jia; Chenglu Bi; Qiuxia Wang; Jing Qiu; Wenjing Zhou; Zhiqiang Zhou (pp. 1423-1427).
A method is described for determination of residues of the insecticide Etofenprox in environmental samples. Anionic surfactant micelle-mediated extraction (coacervation extraction) was evaluated for isolation of Etofenprox before HPLC. The optimum conditions used for extraction included: 0.09 g sodium dodecanesulfonate (SDoS), 3.1 mL (3.3, for concentrations below 0.04 mg L−1) 12 mol L−1 HCl, 5 min vortex stirring, 5 min centrifugation at 4000 rpm, 2 h equilibration time. The limits of quantification (LOQ) and detection (LOD) were 0.01 and 0.004 mg L−1, respectively, and recoveries obtained from five real samples ranged from 94.33±2.48 to 100.13±2.71%. The precision of the method was good; relative standard deviations (RSD) were less than 7%.
Keywords: Etofenprox; Anionic surfactant micelle-mediated extraction; Coacervation extraction; Sodium dodecylsulfonate (SDoS)
Determination of Etofenprox in environmental samples by HPLC after anionic surfactant micelle-mediated extraction (coacervation extraction) by Guifang Jia; Chenglu Bi; Qiuxia Wang; Jing Qiu; Wenjing Zhou; Zhiqiang Zhou (pp. 1423-1427).
A method is described for determination of residues of the insecticide Etofenprox in environmental samples. Anionic surfactant micelle-mediated extraction (coacervation extraction) was evaluated for isolation of Etofenprox before HPLC. The optimum conditions used for extraction included: 0.09 g sodium dodecanesulfonate (SDoS), 3.1 mL (3.3, for concentrations below 0.04 mg L−1) 12 mol L−1 HCl, 5 min vortex stirring, 5 min centrifugation at 4000 rpm, 2 h equilibration time. The limits of quantification (LOQ) and detection (LOD) were 0.01 and 0.004 mg L−1, respectively, and recoveries obtained from five real samples ranged from 94.33±2.48 to 100.13±2.71%. The precision of the method was good; relative standard deviations (RSD) were less than 7%.
Keywords: Etofenprox; Anionic surfactant micelle-mediated extraction; Coacervation extraction; Sodium dodecylsulfonate (SDoS)
A solid-phase microextraction fiber coated with diglycidyloxycalix[4]arene yields very high extraction selectivity and sensitivity during the analysis of chlorobenzenes in soil by Xiujuan Li; Zhaorui Zeng; Ying Xu (pp. 1428-1437).
A novel fiber coated with novel sol-gel (5,11,17,23-tetra-tert-butyl-25,27-dihydroxy-26,28-diglycidyloxycalix[4]arene/hydroxy-terminated silicone oil; diglycidyloxy-C[4]/OH-TSO) was prepared for use with headspace solid-phase microextraction (HS-SPME) combined with gas chromatography (GC) and electron capture detection (ECD), which was applied in order to determine nine chlorobenzenes in soil matrices. Due to the improved fiber preparation, which increases the percentage of calixarene in the coating, the new calixarene fiber exhibits very high extraction selectivity and sensitivity to chlorine-substituted compounds. Various parameters affecting the extraction efficiency were optimized in order to maximize the sensitivity during the chlorobenzene analysis. Interferences from different soil matrices with different characteristics were investigated, and the amount extracted was strongly influenced by the matrix. Therefore, a standard addition protocol was performed on the real soil samples. The linear ranges of detection for the chlorobenzenes tested covered three orders of magnitude, and correlation coefficients >0.9976 and relative standard deviations (RSD) <8% were observed. The detection limits were found at sub-ng/g of soil levels, which were about an order of magnitude lower than those given by the commercial poly(dimethylsiloxane) (PDMS) coating for most of the compounds. The recoveries ranged from 64 to 109.6% for each analyte in the real kaleyard soil matrix when different concentration levels were determined over the linear range, which confirmed the reliability and feasibility of the HS-SPME/GC-ECD approach using the fiber coated with diglycidyloxy-C[4]/OH-TSO for the ultratrace analysis of chlorobenzenes in complex matrices.
Keywords: Gas chromatography; Solid-phase microextraction; Calixarene; Chlorobenzenes; Soil
A solid-phase microextraction fiber coated with diglycidyloxycalix[4]arene yields very high extraction selectivity and sensitivity during the analysis of chlorobenzenes in soil by Xiujuan Li; Zhaorui Zeng; Ying Xu (pp. 1428-1437).
A novel fiber coated with novel sol-gel (5,11,17,23-tetra-tert-butyl-25,27-dihydroxy-26,28-diglycidyloxycalix[4]arene/hydroxy-terminated silicone oil; diglycidyloxy-C[4]/OH-TSO) was prepared for use with headspace solid-phase microextraction (HS-SPME) combined with gas chromatography (GC) and electron capture detection (ECD), which was applied in order to determine nine chlorobenzenes in soil matrices. Due to the improved fiber preparation, which increases the percentage of calixarene in the coating, the new calixarene fiber exhibits very high extraction selectivity and sensitivity to chlorine-substituted compounds. Various parameters affecting the extraction efficiency were optimized in order to maximize the sensitivity during the chlorobenzene analysis. Interferences from different soil matrices with different characteristics were investigated, and the amount extracted was strongly influenced by the matrix. Therefore, a standard addition protocol was performed on the real soil samples. The linear ranges of detection for the chlorobenzenes tested covered three orders of magnitude, and correlation coefficients >0.9976 and relative standard deviations (RSD) <8% were observed. The detection limits were found at sub-ng/g of soil levels, which were about an order of magnitude lower than those given by the commercial poly(dimethylsiloxane) (PDMS) coating for most of the compounds. The recoveries ranged from 64 to 109.6% for each analyte in the real kaleyard soil matrix when different concentration levels were determined over the linear range, which confirmed the reliability and feasibility of the HS-SPME/GC-ECD approach using the fiber coated with diglycidyloxy-C[4]/OH-TSO for the ultratrace analysis of chlorobenzenes in complex matrices.
Keywords: Gas chromatography; Solid-phase microextraction; Calixarene; Chlorobenzenes; Soil
Determination of furfural in an oscillating chemical reaction using an analyte pulse perturbation technique by Jinzhang Gao; Hongxia Dai; Wu Yang; Hua Chen; Dongyu Lv; Jie Ren; Lei Wang (pp. 1438-1443).
A rapid and convenient method for the determination of furfural is presented that is based upon sequential perturbation of the Mn(II)-catalyzed B-Z oscillating system with different amounts of furfural using a continuous-flow stirred tank reactor (CSTR). When the sample was injected, the change in the amplitude and/or period was linearly proportional to the logarithm of the concentration of furfural over the range 3×10−8∼1×10−5 mol L−1. This method gave a detection limit of 3×10−9 mol L−1 under optimum conditions. Finally, the possible mechanism of furfural perturbation in the oscillating reaction is discussed.When the furfural was injected into the Mn(II)-catalyzed B-Z oscillating system, the change in the amplitude and/or period was linearly proportional to the logarithm of the concentration of furfural over the range 3×10−8~1×10−5 mol L−1, with a detection limit of 3×10−9 mol L−1 under optimum conditions.
Keywords: Oscillating chemical reaction; Furfural; APP; CSTR
Determination of furfural in an oscillating chemical reaction using an analyte pulse perturbation technique by Jinzhang Gao; Hongxia Dai; Wu Yang; Hua Chen; Dongyu Lv; Jie Ren; Lei Wang (pp. 1438-1443).
A rapid and convenient method for the determination of furfural is presented that is based upon sequential perturbation of the Mn(II)-catalyzed B-Z oscillating system with different amounts of furfural using a continuous-flow stirred tank reactor (CSTR). When the sample was injected, the change in the amplitude and/or period was linearly proportional to the logarithm of the concentration of furfural over the range 3×10−8∼1×10−5 mol L−1. This method gave a detection limit of 3×10−9 mol L−1 under optimum conditions. Finally, the possible mechanism of furfural perturbation in the oscillating reaction is discussed.When the furfural was injected into the Mn(II)-catalyzed B-Z oscillating system, the change in the amplitude and/or period was linearly proportional to the logarithm of the concentration of furfural over the range 3×10−8~1×10−5 mol L−1, with a detection limit of 3×10−9 mol L−1 under optimum conditions.
Keywords: Oscillating chemical reaction; Furfural; APP; CSTR
Reduction of background interference in the spectrophotometric assay of mevalonate kinase by Linsheng Song (pp. 1444-1445).
Mevalonate kinase can be conveniently assayed by coupling to two other reactions and monitoring the consumption of NADH optically at 340 nm. No mevalonate kinase was detected in crude extracts of Saccharomyces cerevisiae strains, however, because of background interference measured in the absence of mevalonate. A strain of S. cerevisiae over-expressing mevalonate kinase was used to establish conditions for reduction of background interference. This method has been successfully applied to S. cerevisiae strains containing a wild type level of mevalonate kinase.
Keywords: Mevalonate kinase; Mevalonic acid; Isoprenoid
Reduction of background interference in the spectrophotometric assay of mevalonate kinase by Linsheng Song (pp. 1444-1445).
Mevalonate kinase can be conveniently assayed by coupling to two other reactions and monitoring the consumption of NADH optically at 340 nm. No mevalonate kinase was detected in crude extracts of Saccharomyces cerevisiae strains, however, because of background interference measured in the absence of mevalonate. A strain of S. cerevisiae over-expressing mevalonate kinase was used to establish conditions for reduction of background interference. This method has been successfully applied to S. cerevisiae strains containing a wild type level of mevalonate kinase.
Keywords: Mevalonate kinase; Mevalonic acid; Isoprenoid