Analytical sciences : the international journal of the Japan Society for Analytical Chemistry, 2016
A fast and sensitive ion chromatographic method for the simultaneous determinations of six inorga... more A fast and sensitive ion chromatographic method for the simultaneous determinations of six inorganic anions [iodate (IO3(-)), bromate (BrO3(-)), bromide (Br(-)), nitrite (NO2(-)), nitrate (NO3(-)), and iodide (I(-))] in seawater is described using dodecylammonium (DA(+))-coated monolithic octadecylsilyl (ODS) columns, a concentrated aqueous NaCl mobile phase containing dodecylammonium chloride (DAC), and a UV detector. The DA(+)-coated monolithic ODS columns show greater retention for iodate and weaker retention for iodide, compared to dilauryldimethylammonium (DDA(+))-coated monolithic ODS columns. Six anions were determined within 12 min with baseline separation without interferences by matrix ions, such as Cl(-) and SO4(2-), in seawater, compared to a DA(+)-coated particulate ODS column (it took 25 min per sample) obtained previously. The detection limits (DLs) were comparable to the DA(+)-coated particulate ODS column: IO3(-) (7.7 μg L(-1)), BrO3(-) (20), Br(-) (88), NO2(-) (0.9...
A misch metal, an alloy of light rare earth elements, was analyzed by a new coupled analytical me... more A misch metal, an alloy of light rare earth elements, was analyzed by a new coupled analytical method, ITP-PIXE(isotachophoresis—Particle Induced X-ray Emission) : The sample solution containing ca.1 mg misch metal was separated and fractionated by the use of a preparative isotacho-phoretic analyzer. The dropwise fractions containing nanomole rare earth elements were analyzed off-line by PIXE. The matrix effect in X-ray measurement was reduced by the isotachophoretic removing of the dominant lanthanoids and preconcentration of the trace elements of interest. Consequently the minor elements, Sm, Gd, Tb, Dy, Ho, Er, Yb and Y could be determined accurately. The most trace element found was Yb (4ppm, 4ng in 1mg sample). The good accuracy of ITP-PIXE method was also demonstrated for several model samples of lanthanoids, where La was the dominant element and the thirteen lanthanoids were the minor elements. The ratio was varied from 500:1 to 50000:1. Even in the case of 50000:1, ca. 10% a...
Transient isotachophoresis (tITP) is a versatile sample preconcentration technique that uses ITP ... more Transient isotachophoresis (tITP) is a versatile sample preconcentration technique that uses ITP to focus electrically charged analytes at the initial stage of CE analysis. However, according to the ruling principle of tITP, uncharged analytes are beyond its capacity while being separated and detected by micellar electrokinetic chromatography (MEKC). On the other hand, when these are charged micelles that undergo the tITP focusing, one can anticipate the concentration effect, resulting from the formation of transient micellar stack at moving sample/background electrolyte (BGE) boundary, which increasingly accumulates the analytes. This work expands the enrichment potential of tITP for MEKC by demonstrating the quantitative analysis of uncharged metal-based drugs from highly saline samples and introducing to the BGE solution anionic surfactants and buffer (terminating) co-ions of different mobility and concentration to optimize performance. Metallodrugs of assorted lipophilicity were chosen so as to explore whether their varying affinity toward micelles plays the role. In addition to altering the sample and BGE composition, optimization of the detection capability was achieved due to fine-tuning operational variables such as sample volume, separation voltage and pressure, etc. The results of optimization trials shed light on the mechanism of micellar tITP and render effective determination of selected drugs in human urine, with practical limits of detection using conventional UV detector.
For the determination of iodine in food-related materials, the biological sample was decomposed u... more For the determination of iodine in food-related materials, the biological sample was decomposed using a pyrohydrolytic procedure. A sample vessel made from mullite, in which an aliquot of sample was taken, placed in a quartz tube, and heated at 100°C through 820°C step by step under wet oxygen flow. Iodine in the sample was separated by evaporation as hydrogen iodide
Concentration of cadmium in the edible rice is strictly controlled in the sense of food safety. A... more Concentration of cadmium in the edible rice is strictly controlled in the sense of food safety. Among various analytical methods X-ray fluorescence (XRF) analysis is advantageous for the screening of the brown rice because of its strong elemental selectivity and nondestructiveness. Some
Biogenic amines (BAs) play significant roles in indicating human health or food quality. Aiming t... more Biogenic amines (BAs) play significant roles in indicating human health or food quality. Aiming to simultaneously determine three structures (aliphatic, aromatic and heterocyclic) of underivatized BAs, we explored a simple and rapid capillary electrophoresis (CE) method only coupled with conventional UV detector for the separation of thirteen key BAs. The strategy is to choose a UV absorbing probe as co-ion in the background electrolyte (BGE), and different BAs could be characterized by positive or negative peaks according to the fact that their UV absorptivity coefficients at a certain wavelength are better or worse than that of the UV absorbing probe. After the detailed investigation of critical parameters as pH, the concentration of Imidazole (Im) and α-cyclodextrin (α-CD), the optimized BGE consisted of 12.0mmol/L Im as the UV probe and 10.0mmol/L α-CD as the additive (at pH 4.50 adjusted with acetic acid). With such condition, the targets of thirteen BAs were baseline separated...
A simulation of lsotachophorettc eqmhbria has been applied to 287 anions, evaluating R, indices f... more A simulation of lsotachophorettc eqmhbria has been applied to 287 anions, evaluating R, indices for qualitative determmatlon and time-based zone lengths for quantitation under 3 1 leadmg electrolyte conditions in the range pH 3-10, using eight different buffers. The R, values may be useful for correcting asymmetric potentials of sensing electrodes for precise R, measurement, assessmg the separablhty of samples and estimating the optimum separation conditions. The zone lengths for IO-nmol samples obtamed at a drivmg current of 100 PA may be useful for quantitation.
The simultaneous separations of 15 rare-earth (RE) ions including yttrium and lanthanide both by ... more The simultaneous separations of 15 rare-earth (RE) ions including yttrium and lanthanide both by isotachophoresis (ITP) and by capillary zone electrophoresis (CZE) were achieved by using the developed electrolyte systems containing a-hydroxyisobutyric acid (HIBA) as main complexing agent and malonic acid as the assistant one. The successful separation 31 31 31 31 of Y from Dy without loss of the separation of Eu and Gd was briefly summarized. Based on the assumed equilibria existed in steady state zone while using such an electrolyte system with binary complexing agents, the effective mobilities of the RE complex ions and the qualitative indicies (R , the ratio of the specific conductivity of the sample zone to E that of the leading zone) for the RE complex zone were theoretically simulated. The reason for the successful separation was clarified from the view of complex formation, and the simulated isotachopherogram for an optimum electrolyte system was then obtained. The validity of the simulation was checked by comparison of the simulated R with the observed ones. E Furthermore, the historic sample didym prepared from a RE ore by Brauner was analyzed by ITP-particle-induced X-ray emission as well as by CZE, where the supporting electrolyte for CZE analysis is 30 mM creatinine containing 4 mM HIBA and 0.4 mM malonic acid buffered by 2-ethylbutryric acid to pH 4.8.
Se Pu Chinese Journal of Chromatography Zhongguo Hua Xue Hui, Feb 1, 2009
An online preconcentration method, electrokinetic supercharging (EKS) was used for the enrichment... more An online preconcentration method, electrokinetic supercharging (EKS) was used for the enrichment of DNA fragments based on microchip electrophoresis (MCE). EKS is a process that combines electrokinetic injection (EKI) with transient isotachophoresis (tITP). The results demonstrated that the large volume of low concentration sample could be introduced, preconcentrated, and eventually separated on a single channel microchip with the whole length of 40.5 mm. The limit of detection (S/N = 3) of DNA fragments was around 0.07 mg/L, effectively improved 40-fold by EKS preconcentration with the normal UV detection at 260 nm. Some important parameters for enhancing preconcentration and qualitative analysis were examined.
When free flow electrophoresis (FFE) is applied to the separation and purification process under ... more When free flow electrophoresis (FFE) is applied to the separation and purification process under microgravity, higher separability is expected than that under usual 1 G environment, because sedimentation of samples and heat convection can be neglected. Although FFE under micro-gravity is a very important technique for efficient separation of macromolecules because of the above merits, FFE unit (FFEU) should be more sophisticated to give stable operation, high separability, high through-put and high separation efficiency. In this study, fundamental research to achieve FFE with such high performance was done by using a commercial FFEU. The research contains (1) the quantitative study on the separation mode of FFE and separation efficiency, (2) the feasibility analysis of free-flow bidirectional isotachophoresis (FFBITP) which enables separation of cations anions simultaneously by isotachophoresis (ITP) and zone electrophoresis (ZE), (3) the optimization of hardware factors such as thickness of the separation chamber which may cause deterioration of separation due to heat convection, and (4) the analysis of hardware factors depending on the long-time operation. The ultimate goal of this study is to obtain fundamental data for the development of FFE for the international space station. In this paper, the experimental results obtained in a reduced-gravity aircraft was mainly.
Se pu = Chinese journal of chromatography / Zhongguo hua xue hui, 2012
The analysis of seven aliphatic carboxylic acids (formic, acetic, propionic, iso-butyric, n-butyr... more The analysis of seven aliphatic carboxylic acids (formic, acetic, propionic, iso-butyric, n-butyric, iso-valeric and n-valeric acid) in anaerobic digestion process waters for biogas production was examined by ion-exclusion chromatography with dilute acidic eluents (benzoic acid, perfluorobutyric acid (PFBA) and sulfuric acid) and non-suppressed conductivity/ultraviolet (UV) detection. The columns used were a styrene/divinylbenzene-based strongly acidic cation-exchange resin column (TSKgel SCX) and a polymethacrylate-based weakly acidic cation-exchange resin column (TSKgel Super IC-A/C). Good separation was performed on the TSKgel SCX in shorter retention times. For the TSKgel Super IC-A/C, peak shape of the acids was sharp and symmetrical in spite of longer retention times. In addition, the mutual separation of the acids was good except for iso- and n-butyric acids. The better separation and good detection was achieved by using the two columns (TSKgel SCX and TSKgel Super IC-A/C con...
To assess the physiological function of Ca(2+)-dependent protein phosphatase (PP2B) in the yeast ... more To assess the physiological function of Ca(2+)-dependent protein phosphatase (PP2B) in the yeast Saccharomyces cerevisiae, the phenotypes of PP2B-deficient mutants were investigated. Although PP2B was dispensable for growth under normal conditions, the mutations did, however, cause growth inhibition under certain stress circumstances. The growth of the mutants was inhibited by NaCl and LiCl, but not by KCl, CaCl2, MgCl2 or nonspecific osmotic stresses. Upon shift to high NaCl medium, intracellular Na+ levels of both wild type yeast and the mutants initially increased at a comparable rate. However, internal Na+ in wild type cells started to decline more rapidly than the mutant cells during cultivation in high NaCl medium, indicating that PP2B is important in maintaining a gradient across the membrane. The protection against salt stress was achieved, at least in part, by the stimulation of Na+ export. The maintenance of a high level of internal K+ in high NaCl medium was also PP2B-dep...
We proposed a capillary zone electrophoresis (CZE) procedure using field-amplified sample injecti... more We proposed a capillary zone electrophoresis (CZE) procedure using field-amplified sample injection (FASI) for the simultaneous determination of pyridine-triphenylborane (PTPB) and its degradation products: diphenylborinic acid (DPB), phenylboronic acid (MPB), and phenol. The LODs for PTPB, DPB, MPB, and phenol were, respectively, 0.85, 0.88, 44, and 28 μg L -1 . The RSDs (n = 4) for the analytes listed above were in respective ranges of 6.2 -14, 5.9 -10, and 0.49 -0.62% for the peak area, peak height, and migration time. The compounds were extracted from paint-waste samples collected from shipyards using a siliga-gel column. The extract was dissolved with acetonitrile containing 1% (v/v) pyridine. The samples were then analyzed using CZE, revealing respective concentrations of 0.076 -0.53, 0.015 -0.36, 1.7 -22, and 1.2 -13 μg g -1 . The proposed FASI-CZE method is a simple and promising procedure that is expected to be useful for the determination of PTPB and its degradation products in paint wastes.
We developed a novel hybrid sample injection mode (HSIM) that presents the combination of electro... more We developed a novel hybrid sample injection mode (HSIM) that presents the combination of electrokinetic injection and vacuum injection to enhance detection sensitivity in CZE. Samples were introduced using both vacuum and electrokinetic injections simultaneously, with a water plug injected into the capillary prior to sample introduction (i.e. similarly to field-amplified sample injection, FASI). Using a sample mixture containing an anti-fouling agent applied to ship hulls, pyridine-triphenylborane and its degradation products (diphenylborinic acid, phenylboronic acid, and phenol) dissolved in ACN, the length of water plug, time, and voltage for sample introduction were optimized. The signal intensity (peak height) was found to be up to a 30-fold increased using HSIM by applying 4 kV for 4 s at the inlet end of the capillary as the cathode with supplementary vacuum in comparison with only vacuum injection for 4 s. The LODs (at a S/N of 3) for pyridine-triphenylborane, diphenylborinic acid, phenylboronic acid, and phenol were 0.88, 1.0, 21, and 23 mg/L, respectively. At the level of 0.04 mg/L, the RSDs (n 5 4, intraday) for the above analytes were in the ranges of 1.9-11, 4.3-9.2, and 0.34-0.66% for peak area, peak height, and migration time, respectively. The HSIM is a simple and promising procedure useful for enhancing the sensitivity for both low-and high-mobility ions in CZE.
Analytical sciences : the international journal of the Japan Society for Analytical Chemistry, 2016
A fast and sensitive ion chromatographic method for the simultaneous determinations of six inorga... more A fast and sensitive ion chromatographic method for the simultaneous determinations of six inorganic anions [iodate (IO3(-)), bromate (BrO3(-)), bromide (Br(-)), nitrite (NO2(-)), nitrate (NO3(-)), and iodide (I(-))] in seawater is described using dodecylammonium (DA(+))-coated monolithic octadecylsilyl (ODS) columns, a concentrated aqueous NaCl mobile phase containing dodecylammonium chloride (DAC), and a UV detector. The DA(+)-coated monolithic ODS columns show greater retention for iodate and weaker retention for iodide, compared to dilauryldimethylammonium (DDA(+))-coated monolithic ODS columns. Six anions were determined within 12 min with baseline separation without interferences by matrix ions, such as Cl(-) and SO4(2-), in seawater, compared to a DA(+)-coated particulate ODS column (it took 25 min per sample) obtained previously. The detection limits (DLs) were comparable to the DA(+)-coated particulate ODS column: IO3(-) (7.7 μg L(-1)), BrO3(-) (20), Br(-) (88), NO2(-) (0.9...
A misch metal, an alloy of light rare earth elements, was analyzed by a new coupled analytical me... more A misch metal, an alloy of light rare earth elements, was analyzed by a new coupled analytical method, ITP-PIXE(isotachophoresis—Particle Induced X-ray Emission) : The sample solution containing ca.1 mg misch metal was separated and fractionated by the use of a preparative isotacho-phoretic analyzer. The dropwise fractions containing nanomole rare earth elements were analyzed off-line by PIXE. The matrix effect in X-ray measurement was reduced by the isotachophoretic removing of the dominant lanthanoids and preconcentration of the trace elements of interest. Consequently the minor elements, Sm, Gd, Tb, Dy, Ho, Er, Yb and Y could be determined accurately. The most trace element found was Yb (4ppm, 4ng in 1mg sample). The good accuracy of ITP-PIXE method was also demonstrated for several model samples of lanthanoids, where La was the dominant element and the thirteen lanthanoids were the minor elements. The ratio was varied from 500:1 to 50000:1. Even in the case of 50000:1, ca. 10% a...
Transient isotachophoresis (tITP) is a versatile sample preconcentration technique that uses ITP ... more Transient isotachophoresis (tITP) is a versatile sample preconcentration technique that uses ITP to focus electrically charged analytes at the initial stage of CE analysis. However, according to the ruling principle of tITP, uncharged analytes are beyond its capacity while being separated and detected by micellar electrokinetic chromatography (MEKC). On the other hand, when these are charged micelles that undergo the tITP focusing, one can anticipate the concentration effect, resulting from the formation of transient micellar stack at moving sample/background electrolyte (BGE) boundary, which increasingly accumulates the analytes. This work expands the enrichment potential of tITP for MEKC by demonstrating the quantitative analysis of uncharged metal-based drugs from highly saline samples and introducing to the BGE solution anionic surfactants and buffer (terminating) co-ions of different mobility and concentration to optimize performance. Metallodrugs of assorted lipophilicity were chosen so as to explore whether their varying affinity toward micelles plays the role. In addition to altering the sample and BGE composition, optimization of the detection capability was achieved due to fine-tuning operational variables such as sample volume, separation voltage and pressure, etc. The results of optimization trials shed light on the mechanism of micellar tITP and render effective determination of selected drugs in human urine, with practical limits of detection using conventional UV detector.
For the determination of iodine in food-related materials, the biological sample was decomposed u... more For the determination of iodine in food-related materials, the biological sample was decomposed using a pyrohydrolytic procedure. A sample vessel made from mullite, in which an aliquot of sample was taken, placed in a quartz tube, and heated at 100°C through 820°C step by step under wet oxygen flow. Iodine in the sample was separated by evaporation as hydrogen iodide
Concentration of cadmium in the edible rice is strictly controlled in the sense of food safety. A... more Concentration of cadmium in the edible rice is strictly controlled in the sense of food safety. Among various analytical methods X-ray fluorescence (XRF) analysis is advantageous for the screening of the brown rice because of its strong elemental selectivity and nondestructiveness. Some
Biogenic amines (BAs) play significant roles in indicating human health or food quality. Aiming t... more Biogenic amines (BAs) play significant roles in indicating human health or food quality. Aiming to simultaneously determine three structures (aliphatic, aromatic and heterocyclic) of underivatized BAs, we explored a simple and rapid capillary electrophoresis (CE) method only coupled with conventional UV detector for the separation of thirteen key BAs. The strategy is to choose a UV absorbing probe as co-ion in the background electrolyte (BGE), and different BAs could be characterized by positive or negative peaks according to the fact that their UV absorptivity coefficients at a certain wavelength are better or worse than that of the UV absorbing probe. After the detailed investigation of critical parameters as pH, the concentration of Imidazole (Im) and α-cyclodextrin (α-CD), the optimized BGE consisted of 12.0mmol/L Im as the UV probe and 10.0mmol/L α-CD as the additive (at pH 4.50 adjusted with acetic acid). With such condition, the targets of thirteen BAs were baseline separated...
A simulation of lsotachophorettc eqmhbria has been applied to 287 anions, evaluating R, indices f... more A simulation of lsotachophorettc eqmhbria has been applied to 287 anions, evaluating R, indices for qualitative determmatlon and time-based zone lengths for quantitation under 3 1 leadmg electrolyte conditions in the range pH 3-10, using eight different buffers. The R, values may be useful for correcting asymmetric potentials of sensing electrodes for precise R, measurement, assessmg the separablhty of samples and estimating the optimum separation conditions. The zone lengths for IO-nmol samples obtamed at a drivmg current of 100 PA may be useful for quantitation.
The simultaneous separations of 15 rare-earth (RE) ions including yttrium and lanthanide both by ... more The simultaneous separations of 15 rare-earth (RE) ions including yttrium and lanthanide both by isotachophoresis (ITP) and by capillary zone electrophoresis (CZE) were achieved by using the developed electrolyte systems containing a-hydroxyisobutyric acid (HIBA) as main complexing agent and malonic acid as the assistant one. The successful separation 31 31 31 31 of Y from Dy without loss of the separation of Eu and Gd was briefly summarized. Based on the assumed equilibria existed in steady state zone while using such an electrolyte system with binary complexing agents, the effective mobilities of the RE complex ions and the qualitative indicies (R , the ratio of the specific conductivity of the sample zone to E that of the leading zone) for the RE complex zone were theoretically simulated. The reason for the successful separation was clarified from the view of complex formation, and the simulated isotachopherogram for an optimum electrolyte system was then obtained. The validity of the simulation was checked by comparison of the simulated R with the observed ones. E Furthermore, the historic sample didym prepared from a RE ore by Brauner was analyzed by ITP-particle-induced X-ray emission as well as by CZE, where the supporting electrolyte for CZE analysis is 30 mM creatinine containing 4 mM HIBA and 0.4 mM malonic acid buffered by 2-ethylbutryric acid to pH 4.8.
Se Pu Chinese Journal of Chromatography Zhongguo Hua Xue Hui, Feb 1, 2009
An online preconcentration method, electrokinetic supercharging (EKS) was used for the enrichment... more An online preconcentration method, electrokinetic supercharging (EKS) was used for the enrichment of DNA fragments based on microchip electrophoresis (MCE). EKS is a process that combines electrokinetic injection (EKI) with transient isotachophoresis (tITP). The results demonstrated that the large volume of low concentration sample could be introduced, preconcentrated, and eventually separated on a single channel microchip with the whole length of 40.5 mm. The limit of detection (S/N = 3) of DNA fragments was around 0.07 mg/L, effectively improved 40-fold by EKS preconcentration with the normal UV detection at 260 nm. Some important parameters for enhancing preconcentration and qualitative analysis were examined.
When free flow electrophoresis (FFE) is applied to the separation and purification process under ... more When free flow electrophoresis (FFE) is applied to the separation and purification process under microgravity, higher separability is expected than that under usual 1 G environment, because sedimentation of samples and heat convection can be neglected. Although FFE under micro-gravity is a very important technique for efficient separation of macromolecules because of the above merits, FFE unit (FFEU) should be more sophisticated to give stable operation, high separability, high through-put and high separation efficiency. In this study, fundamental research to achieve FFE with such high performance was done by using a commercial FFEU. The research contains (1) the quantitative study on the separation mode of FFE and separation efficiency, (2) the feasibility analysis of free-flow bidirectional isotachophoresis (FFBITP) which enables separation of cations anions simultaneously by isotachophoresis (ITP) and zone electrophoresis (ZE), (3) the optimization of hardware factors such as thickness of the separation chamber which may cause deterioration of separation due to heat convection, and (4) the analysis of hardware factors depending on the long-time operation. The ultimate goal of this study is to obtain fundamental data for the development of FFE for the international space station. In this paper, the experimental results obtained in a reduced-gravity aircraft was mainly.
Se pu = Chinese journal of chromatography / Zhongguo hua xue hui, 2012
The analysis of seven aliphatic carboxylic acids (formic, acetic, propionic, iso-butyric, n-butyr... more The analysis of seven aliphatic carboxylic acids (formic, acetic, propionic, iso-butyric, n-butyric, iso-valeric and n-valeric acid) in anaerobic digestion process waters for biogas production was examined by ion-exclusion chromatography with dilute acidic eluents (benzoic acid, perfluorobutyric acid (PFBA) and sulfuric acid) and non-suppressed conductivity/ultraviolet (UV) detection. The columns used were a styrene/divinylbenzene-based strongly acidic cation-exchange resin column (TSKgel SCX) and a polymethacrylate-based weakly acidic cation-exchange resin column (TSKgel Super IC-A/C). Good separation was performed on the TSKgel SCX in shorter retention times. For the TSKgel Super IC-A/C, peak shape of the acids was sharp and symmetrical in spite of longer retention times. In addition, the mutual separation of the acids was good except for iso- and n-butyric acids. The better separation and good detection was achieved by using the two columns (TSKgel SCX and TSKgel Super IC-A/C con...
To assess the physiological function of Ca(2+)-dependent protein phosphatase (PP2B) in the yeast ... more To assess the physiological function of Ca(2+)-dependent protein phosphatase (PP2B) in the yeast Saccharomyces cerevisiae, the phenotypes of PP2B-deficient mutants were investigated. Although PP2B was dispensable for growth under normal conditions, the mutations did, however, cause growth inhibition under certain stress circumstances. The growth of the mutants was inhibited by NaCl and LiCl, but not by KCl, CaCl2, MgCl2 or nonspecific osmotic stresses. Upon shift to high NaCl medium, intracellular Na+ levels of both wild type yeast and the mutants initially increased at a comparable rate. However, internal Na+ in wild type cells started to decline more rapidly than the mutant cells during cultivation in high NaCl medium, indicating that PP2B is important in maintaining a gradient across the membrane. The protection against salt stress was achieved, at least in part, by the stimulation of Na+ export. The maintenance of a high level of internal K+ in high NaCl medium was also PP2B-dep...
We proposed a capillary zone electrophoresis (CZE) procedure using field-amplified sample injecti... more We proposed a capillary zone electrophoresis (CZE) procedure using field-amplified sample injection (FASI) for the simultaneous determination of pyridine-triphenylborane (PTPB) and its degradation products: diphenylborinic acid (DPB), phenylboronic acid (MPB), and phenol. The LODs for PTPB, DPB, MPB, and phenol were, respectively, 0.85, 0.88, 44, and 28 μg L -1 . The RSDs (n = 4) for the analytes listed above were in respective ranges of 6.2 -14, 5.9 -10, and 0.49 -0.62% for the peak area, peak height, and migration time. The compounds were extracted from paint-waste samples collected from shipyards using a siliga-gel column. The extract was dissolved with acetonitrile containing 1% (v/v) pyridine. The samples were then analyzed using CZE, revealing respective concentrations of 0.076 -0.53, 0.015 -0.36, 1.7 -22, and 1.2 -13 μg g -1 . The proposed FASI-CZE method is a simple and promising procedure that is expected to be useful for the determination of PTPB and its degradation products in paint wastes.
We developed a novel hybrid sample injection mode (HSIM) that presents the combination of electro... more We developed a novel hybrid sample injection mode (HSIM) that presents the combination of electrokinetic injection and vacuum injection to enhance detection sensitivity in CZE. Samples were introduced using both vacuum and electrokinetic injections simultaneously, with a water plug injected into the capillary prior to sample introduction (i.e. similarly to field-amplified sample injection, FASI). Using a sample mixture containing an anti-fouling agent applied to ship hulls, pyridine-triphenylborane and its degradation products (diphenylborinic acid, phenylboronic acid, and phenol) dissolved in ACN, the length of water plug, time, and voltage for sample introduction were optimized. The signal intensity (peak height) was found to be up to a 30-fold increased using HSIM by applying 4 kV for 4 s at the inlet end of the capillary as the cathode with supplementary vacuum in comparison with only vacuum injection for 4 s. The LODs (at a S/N of 3) for pyridine-triphenylborane, diphenylborinic acid, phenylboronic acid, and phenol were 0.88, 1.0, 21, and 23 mg/L, respectively. At the level of 0.04 mg/L, the RSDs (n 5 4, intraday) for the above analytes were in the ranges of 1.9-11, 4.3-9.2, and 0.34-0.66% for peak area, peak height, and migration time, respectively. The HSIM is a simple and promising procedure useful for enhancing the sensitivity for both low-and high-mobility ions in CZE.
Uploads
Papers by Takeshi Hirokawa