Shiuh-Jen Jiang

Determination of arsenic compounds in water samples by liquid chromatography-inductively coupled plasma mass spectrometry with an in situ nebulizer-hydride generator

A preliminary study of an in situ nebulizer-hydride generator as a sample introduction device for an inductively coupled plasma mass spectrometry (ICP-MS) system is described. The samples were ionic arsenic compounds that had undergone chromatographic separation before injection into the hydride generator. l-Cysteine was used instead of potassium iodide as the prereductant. Only mild treatment with nitric acid was necessary to obtain a satisfactory hydride efficiency. The sensitivity, detection limits and reproducibility of a liquid chromatographic (LC)-ICP-MS system with a hydride generator were comparable to or better than an LC-ICP-MS system with conventional pneumatic nebulization or other sample introduction techniques. The limits of detection for various arsenic species were in the range 11-51 ng l−1. The concentrations of various arsenic species in several natural water samples were determined.

Speciation of tin by reversed phase liquid chromatography with inductively coupled plasma mass spectrometric detection

An inductively coupled plasma mass spectrometer (ICP-MS) coupled with ultrasonic nebulization was used as a liquid chromatographic detector for the determination of tin compounds. Inorganic tin, trimethyltin, triethyltin, tripropyltin, tributyltin, and triphenyltin were separated by reversed phase liquid chromatography. The separation was complete in less than 6 min. Detection limits were in the range of 2.8–16 pg Sn for various tin species. The relative standard deviation of the peak areas for five injections of 50 μg 1−1 organotin mixture was in the range of 6–9%. This method has been applied to determine various tin species in harbour sediment reference sample PACS-1 and harbour water sample.

Determination of selenium compounds in urine samples by liquid chromatography-inductively coupled plasma mass spectrometry with an ultrasonic nebulizer

Abstract An inductively coupled plasma mass spectrometer (ICP-MS) coupled with ultrasonic nebulization was used as a liquid chromatographic detector for the determination of selenium compounds. Selenite, selenate, and trimethylselenonium were separated by ion-pair reversed-phase liquid chromatography before introduction into the inductively coupled plasma. Detection limits were in the range of 22–74 pg selenium for various selenium species. The relative standard deviation of the peak heights for five injections of 10 ng ml−1 selenium mixture was in the range of 2–5%. This method has been applied to determine various selenium species in urine samples.

Electrothermal vaporization inductively coupled plasma-mass spectrometry for the determination of Cr, Cu, Cd, Hg and Pb in rice flour

Abstract Ultrasonic slurry sampling (USS)–electrothermal vaporization (ETV) dynamic reaction cell™ (DRC) inductively coupled plasma-mass spectrometry (ICP-MS) has been applied to determine Cr, Cu, Cd, Hg and Pb in rice samples. The influences of instrument operating conditions and slurry preparation on the ion signals were reported. Ascorbic acid was used as a modifier to enhance the ion signals. The background ions at the chromium masses were reduced in intensity significantly by using 0.4xa0mlxa0min −1 NH 3 as reaction cell gas in the dynamic reaction cell while a q value of 0.6 was used. Since the sensitivities of Cr, Cu, Cd, Hg and Pb in rice flour slurry and aqueous solution were quite different, standard addition and isotope dilution methods were used for the determination of Cr, Cu, Cd, Hg and Pb in these rice samples. This method has been applied to the determination of Cr, Cu, Cd, Hg and Pb in NIST SRM 1568a rice flour reference material and two rice samples purchased from the market. The analytical results for the reference material agreed with the certified values. The results for the rice samples for which no reference values were available were also found to be in good agreement between the isotope dilution and standard addition methods. The method’s detection limits estimated from the standard addition plots were about 0.44, 1.7, 0.4, 0.53 and 0.69xa0ngxa0g −1 for Cr, Cu, Cd, Hg and Pb, respectively, in the original rice flour.

Determination of mercury compounds by capillary electrophoresis inductively coupled plasma mass spectrometry with microconcentric nebulization

Abstract A preliminary study of a microconcentric nebulizer (MCN) as the sample introduction device for the capillary electrophoresis inductively coupled plasma mass spectrometry (CE-ICP-MS) system for mercury speciation application is described. Samples containing ionic mercury compounds were subjected to electrophoretic separation before injection into the microconcentric nebulizer. The species studied include inorganic mercury (Hg(II)), methyl mercury (CH 3 -Hg) and ethyl mercury (C 2 H 5 -Hg). The sensitivity, detection limit and repeatability of the CE-ICP-MS system with a microconcentric nebulizer were comparable to CE-ICP-MS system with other nebulization techniques of various metal speciation studies . Reproducibility of peak height and migration time was better than 3 and 2%, respectively. The limits of detection for various mercury species were in the range of 0.08–0.17xa0μgxa0ml −1 Hg based on peak height. We determined the concentrations of mercury compound in contact lenses solutions purchased from the local market. The precision between sample replicates was better than 7% with CE-MCN-ICP-MS method.

Determination of chromium in water and urine by reaction cell inductively coupled plasma mass spectrometry

An inductively coupled plasma mass spectrometry (ICP-MS) instrument equipped with a dynamic reaction cell (DRC) was used for the determination of chromium in water and urine samples. The effect of the operating conditions of the DRC system was studied to get the best signal-to-noise ratio. The potentially interfering 40Ar12C+, 35Cl16OH+, 34S18O, 40Ar12CH+ and 37Cl16O+ ions at the chromium masses m/z 52 and 53 were reduced in intensity by approximately 2–3 orders of magnitude by using 1.0xa0mlxa0min−1 NH3 as reaction cell gas in the DRC while a q value of 0.6 was used. The limits of detection for 52Cr and 53Cr were 0.015 and 0.024xa0ngxa0ml−1 Cr, respectively. This nmethod was applied to determine Cr in NRCC SLRS-3 Riverine Water reference sample, NIST SRM 1643d Trace Elements in Water, NIST SRM 2670 Urine reference sample and several water and urine samples collected locally. The external calibration method and isotope dilution method were used for the determination of Cr in selected samples. The results for the reference samples agreed satisfactorily with the reference values. Results for other samples analyzed by different quantitation methods agreed satisfactorily. Precision between sample replicates was better than 20% for most of the determinations.

Determination of calcium, iron and zinc in milk powder by reaction cell inductively coupled plasma mass spectrometry

Abstract An inductively coupled plasma mass spectrometer (ICP-MS) equipped with a dynamic reaction cell™ (DRC) was used for the determination of Ca, Fe and Zn in milk powder samples. The effect of the operating conditions of the DRC system was studied to get the best signal-to-noise (S/N) ratio. The potentially interfering 40 Ar + , 40 Ar 16 O + , 40 Ca 16 O + , 48 Ca 16 O + and 32 S 16 O 16 O + at the masses m/z 40, 56 and 64 were reduced in intensity significantly by using CH4 as the reaction cell gas in the DRC while a q-value of 0.7 was used. The limits of detection for 40 Ca , 56 Fe and 64Zn estimated from the external calibration graphs were 1, 0.01 and 0.001xa0ngxa0ml−1, respectively, which correspond to 1000, 10 and 1xa0ngxa0g−1 in the original powder sample. This method was applied to the determination of Ca, Fe and Zn in NIST SRM 1549 non-fat milk powder and two milk powder samples purchased locally. The results for the reference sample agreed satisfactorily with the reference values; the accuracy of the determination was better than 3.8, 18 and 2.2% for Ca, Fe and Zn, respectively. The results for which no reference value was available were also found to be in good agreement between different isotopes. Precision (R.S.D.) between sample replicates was better than 10% for all the determinations.

Determination of chromium species in water samples by liquid chromatography-inductively coupled plasma-dynamic reaction cell-mass spectrometry

An inductively coupled plasma-mass spectrometer (ICP-MS) equipped with a dynamic reaction cell (DRC) was used as a liquid chromatographic detector for the determination of chromium species. In this study, ionic chromium species (CrIII and CrVI) were separated by reversed-phase liquid chromatography (LC) with a C8 column as the stationary phase and 0.6xa0mmolxa0l−1 EDTA, 2xa0mmolxa0l−1 tetrabutylammonium phosphate and 2% v/v methanol solution (pHxa06.9) as the mobile phase. The potentially interfering 40Ar12C+, 35Cl16OH+, 40Ar12CH+ and 37Cl16O+ at the chromium masses m/z 52 and 53 were reduced in intensity by approximately three orders of magnitude by using 0.65xa0mlxa0min−1 nNH3 as reaction cell gas in the DRC. Effluent from the LC column was delivered to the nebulization system and the ICP-MS for the determination of chromium. The repeatability of the peak area was better than 2% at m/z 52. The limits of detection for CrIII and CrVI were 0.063 and 0.061xa0ngxa0ml−1 Cr at m/z 52, respectively, based on peak height. The concentrations of chromium species have been determined in several water samples collected from Kaohsiung area. The recovery was in the range of 90–110% for all the determinations.

Organic acids as the modifier to determine Zn, Cd, Tl and Pb in soil by slurry sampling electrothermal vaporization inductively-coupled plasma mass spectrometry

Abstract Ultrasonic slurry sampling electrothermal vaporization inductively-coupled plasma mass spectrometry (USS-ETV-ICP-MS) has been applied to the determination of Zn, Cd, Tl and Pb in several soil samples. A mixture of 1% m/v EDTA and 1.5% m/v of ascorbic acid was used as the modifier to enhance the ion signals. The influences of instrument operating conditions and slurry preparation on the ion signals were reported. In this study, a relatively low vaporization temperature was used which separated the analyte from the major matrix components and improved the ion signals significantly. With ETV sample introduction device, spectroscopic and nonspectroscopic interferences were alleviated significantly. Since the sensitivities of Zn, Cd, Tl and Pb in various soil slurries and aqueous solution were different, standard addition method and isotope dilution method were used for the determination of Zn, Cd, Tl and Pb in these soil samples. This method has been applied to the determination of Zn, Cd, Tl and Pb in NIST SRM 2711 Montana soil reference material and several soil samples collected from Kaohsiung area. The analysis results were agreed with the certified values. The precision between sample replicates was better than 9% with USS-ETV-ICP-MS method. Detection limits estimated from standard addition curves were about 260–620, 3–5, 0.3–1 and 9–20xa0ngxa0g−1 for Zn, Cd, Tl and Pb, respectively, in different samples.

A novel cloud point extraction approach using cationic surfactant for the separation and pre-concentration of chromium species in natural water prior to ICP-DRC-MS determination.

A novel cloud point phase separation of cationic surfactant, Aliquat-336 and capabilities of its reactive solubilizing sites for selective extraction of chromium species at ultra trace levels was examined in natural water. The phase separation behavior of Aliquat-336 is studied with various additives. The nonionic surfactant, Triton X-114 was found to induce the cloud point phase separation of Aliquat-336. The separation of anionic Cr(VI) was enabled by the formation of ion associate with quaternary ammonium head group of Aliquat-336 at pH 2, and the recovery of Cr(VI) and Cr(III) were 101.4+/-1.4% and 2.2+/-0.4%, respectively at 0.5-1 ng mL(-1), Total Cr was pre-concentrated as Cr-APDC species using the hydrophobic tail group at pH 6.5. The Cr(III) concentration was obtained by subtracting Cr(VI) from total Cr. The recovery of total Cr was 99.5+/-1.2%. Parameters affecting extraction were assessed. The procedure was applied to NIST 1643c and NIST 1643d waters, and the sum of individual species obtained was compared with the certified chromium values. The method was also applied to various natural waters with limits of detection and pre-concentration factor of 0.010 and 0.025 ng mL(-1); 10 and 10, respectively, for Cr(VI) and Cr(III)-APDC using ICP-MS operated in DRC mode.