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    • Determination of Trace Copper in Biological Samples by On-line Chemical Vapor Generation-Atomic Fluorescence Spectrometry

      2008, 29(3):93-98. DOI: 10.46770/AS.2008.03.004

      Abstract (248) HTML (0) PDF 146.88 K (1759) Comment (0) Favorites

      Abstract:On-line chemical vapor generation atomic fluorescence spectrometry (CVG-AFS) was, for the first time, used to determine trace copper in biological samples by merging acidified sample solution with potassium tetrahydroborate aqueous solution in the presence of micro-amounts of 1,10-phenanthroline. Nitric acid, for both sample digestion and chemical vapor generation, was used as the acid medium. CVG conditions and instrumental parameters were optimized for the best CVG efficiency, good gas/liquid separation, and efficient atomization/excitation. Under the optimized conditions, a limit of detection of 4 ng mL(-1) was obtained for copper, with a linear dynamic range of over three orders of magnitude. The proposed method was successfully applied to the determination of copper in biological certified reference materials.

    • Rapid Determination of Chemical Oxygen Demand by Flame AAS Based on Flow Injection On-line Ultrasound- assisted Digestion and Manganese Speciation Separation

      2004, 25(4):191-196. DOI: 10.46770/AS.2004.04.006

      Abstract (233) HTML (0) PDF 86.02 K (1599) Comment (0) Favorites

      Abstract:A rapid, sensitive, and cost-effective method was developed for the determination of trace mercury in water samples by on-line coupling of flow injection (FI) sorption preconcentration with oxidative elution to cold vapor atomic fluorescence spectrometry (CV-AFS). race Hg(II) in aqueous solution was preconcentrated by on-line formation of mercury diethyldithiocarbamate complex (Hg-DDTC) and adsorption of the resulting neutral complex on the inner walls of a PTFE knotted reactor (KR). A mixture of 16% (v/v) HCl and 10% (v/v) H2O2 was used as the eluent to remove the adsorbed Hg-DDTC from the KR, then convert on-line the Hg-DDTC into Hg(II) prior to its reduction to elemental mercury by KBH4 for subsequent on-line CV-AFS detection. The tolerable concentrations of Cd(II) As(Ill) Se(IV) Fe(III), Co(II), Ni(II), and Cu(II) and Cu(II) for the determination of 0.1 mug L-I Hg(II) were 0.1, 10, 0.1, 0.1, 0.7, 1, 0.3, and 0.2 mg L-1, respectively. With a sample loading flow rate of 3.1 mL, min(-1) for a 60-s preconcentration, a detection limit (3sigma) of 4.4 ng L-I was achieved at a sample throughput of 36 samples h(-1). The precision (RSD, n = 11) was 1.7% at the 1 0, 1-mug L-1 Hg (11) level. The method was successfully applied to the determination of mercury in a certified reference material, GBW(E) 080392, and a number of local natural water samples.

    • Determination of Cadmium at the Nanogram per Liter Level in Seawater by Graphite Furnace AAS Using Cloud Point Extraction

      2004, 25(4):170-176. DOI: 10.46770/AS.2004.04.003

      Abstract (242) HTML (0) PDF 99.16 K (1736) Comment (0) Favorites

      Abstract:A method based on?cloud?point?extraction?was developed to determine?cadmium?at?the?nanogram?per?liter?level?in?sea-water?by?graphite?furnace?atomic absorption spectrometry. Diethyldithiocarbamate (DDTC) was used as?the?chelating reagent to form Cd-DDTC complex; Triton X-114 was added as?the?surfactant.?The?parameters affecting sensitivity and?extraction?efficiency (i.e., pH?of?the?solution, concentration?of?DDTC and Triton X-114, equilibration temperature, and centrifugation time) were evaluated and optimized. Under?the?optimum conditions, a preconcentration factor?of?51.6 was obtained for a 20-ml, water sample.?The?detection limit was as low as 2.0 ng L-1 and?the?analytical curve was linear?in?the?10.0-200.0 ng L-1 range with satisfactory precision (RSD < 4.7%).?The?proposed method was successfully applied to?the?trace?determination?of?cadmium?in?seawater.

    • Development and Validation Method for the Determination of Rare Earth Impurities in High Purity Neodymium Oxide by ICP-MS

      2004, 25(1):13-20. DOI: 10.46770/AS.2004.01.002

      Abstract (215) HTML (0) PDF 154.90 K (1722) Comment (0) Favorites

      Abstract:The analytical procedure for the determination of trace rare earth impurities in high purity neodymium oxide (Nd2O3) by ICP-MS is described. The effect of ICP-MS operating parameters on the REO(H)(+)/RE+ production ratio was studied in detail, and the optimal ICP operating conditions were established. In this context, the relationship between REO(H)(+)/RE+ production ratio and the bond strength of the rare earth oxides is also discussed briefly. For the correction of the spectral interference induced by the matrix (neodymium), a simple correction equation was used for correcting the interferences of the polyatomic ions NdO+ and NdOH+ with Tb-159 and Ho-165. The proposed method was applied to the determination of trace rare earth impurities in high purity Nd2O3\, and the analytical results were in good agreement with the recommended reference values.

    • Multielement Analysis of Alkaline-Resistant Glass and Basalt Glass Fibers Using Laser Ablation ICP-MS: A Useful Tool in Technical Textile Quality Control

      2002, 23(1):1-6. DOI: 10.46770/AS.2002.01.001

      Abstract (328) HTML (0) PDF 135.56 K (1860) Comment (0) Favorites

      Abstract:A powerful multielement analytical technique using laser ablation Inductively coupled plasma source mass spectrometry (LA-ICP-MS) for the sensitive determination of trace impurities in thin glass filaments, used as reinforcing material in the construction industry, was developed. The trace analysis was carried out directly on very thin solid strands (without any sample preparation steps) by LA-ICP-MS whereby a bundle of thin glass fibers (with a filament diameter of about 10 - 20 mum) was fixed on a thin, special tape of a target holder. The fibers were ablated in the ablation chamber with the aid of a commercial laser ablation system using a Nd-YAG laser at a wavelength of 266 nm). In order to verify the trace analytical data, the ablated T-glass fibers were analyzed using a quadrupole (LA-ICP-QMS) and double-focusing sector field mass spectrometer (LA-ICP-SFMS). The detection limits of the trace elements in glass fibers using the LA-ICP-MS with a quadrupole analyzer were in the sub mug g(-1) range, whereas using a sector,field mass spectrometer (LA-ICP-SFMS) the detection limits could be Improved by 3-4 orders of magnitude down to the low and sub ng g(-1) range. The multielement trace analytical method, developed for high-purity glass fibers, was applied to the determination of chemical composition on thin alkati-resistant glass and basalt fibers with finishing additives used in fine concrete for the building industry. The analytical results were quantified using standard reference materials (SRMs) of glass matrix, such as the NIST 612 glass SRM and the basalt geological reference glasses, KL-2G and ML3B-G, for the trace analysis of basalt glass fibers. The experimentally determined relative sensitivity coefficients (RSC) in LA-ICP-MS for both SRMs varied between 0.2 and 3 for most of the elements. An increase of the relative sensitivity coefficients was observed with increasing mass. The relative standard deviation (RSD) of most elements (N = 3) was T between 2 and 10%. The results of the trace element concentrations by LA-ICP-MS using different instrumentation are in good agreement.

    • On-line Ion Exchange Preconcentration in a Sequential Injection Lab-on-valve Microsystem Incorporating a Renewable Column With ETAAS for the Trace Level Determination of Bismuth in Urine and River Sediment

      2001, 22(3):312-318. DOI: 10.46770/AS.2001.03.003

      Abstract (204) HTML (0) PDF 167.98 K (1610) Comment (0) Favorites

      Abstract:A?sequential?injection?system?for?on-line?ion exchange separation and?preconcentration?of trace level amounts of metal ions with ensuing detection by electrothermal atomic absorption spectrometry (ETAAS) is described. Based on the use of?a?renewable microcolumn incorporated within an integrated lab-on-valve microsystem, the?column?is initially loaded with?a?defined volume of beads of an SP Sephadex C-25 cation exchange resin. After having been exposed to?a?metered amount of sample solution, the loaded bead suspension is precisely manipulated within the valve to allow reproducible elution of the retained analyte by 30 muL nitric acid (1: 16,v/v) which, via air segmentation, are then transported into the graphite tube for quantification. The content of the used?column?is afterwards discarded and new?column?material is aspirated for the next run. The ETAAS determination is performed in parallel with the?preconcentration?process of the ensuing sample. The performance of the?system?is demonstrated for the determination of bismuth. With 2.4-mL sample loading, an enrichment factor of 33.4,?a?detection limit of 27 ng 1:1, along with?a?sampling frequency of 10 h(-1) was obtained. The relative standard deviation was 2.3% for the determination of 2.0 mg 1:1 Bi (n = 7). The procedure was validated by determination of bismuth in?a?certified reference material CRM 320 (river sediment) and by bismuth spike recoveries in two human urine samples.

    • A Sequential Injection On-Line Column Preconcentration System for Electrothermal AAS Determination of Thallium in Geochemical Samples

      2000, 21(1):17-22. DOI: 10.46770/AS.2000.01.004

      Abstract (180) HTML (0) PDF 116.38 K (1566) Comment (0) Favorites

      Abstract:A?sequential?injection?system?for?on-line?sorbent extraction?preconcentration?in electrothermal atomic absorption spectroscopy was developed for the determination of trace thallium in geochemical samples. The TlBr4-1 complex was adsorbed on?a?20-mu L micro-column?(located at the tip of the furnace sampling probe) packed with XAD-8 resin. After sequentially aspirating separate zones of acetone, rinsing acid, and sample (pretreated with bromine) into?a?2.5-m long, 1-mm i.d. holding coil, the flow was reversed and directed to the?column. Sample loading, analyte adsorption,?column?rinsing and analyte elution were achieved within?a?single reversed syringe stroke. The adsorbed analyte was eluted into the furnace with 50 mu L acetone. Mutual mixing between sample, rinsing acid, and eluent were prevented by separating the zones with small air segments during metering. Tightening of?column?packing was avoided by?a?slight back-suction through the?column?after each operational cycle. With 1-mL sample loading, an enrichment factor of 15 was obtained with?a?detection limit of 18 ng/L thallium (3 sigma).?A?precision of 2.4% RSD (n=11, 4 μ g/L) and?a?sampling frequency of 11/hour were achieved. The method was applied to the analysis of geochemical samples. The results were in good agreement with the certified values of standard reference geochemical materials.

    • Trace Metals in Traditional Chinese Medicine: A Preliminary Study Using ICP-MS for Metal Determination and As Speciation

      1999, 20(3):86-91. DOI: 10.46770/AS.1999.03.002

      Abstract (278) HTML (0) PDF 283.26 K (1776) Comment (0) Favorites

      Abstract:The metal content in several TCM drugs was determined by ICP-MS. The efficiencies of different sample digestion methods were compared. Since one of the products studied is known to contain arsenic sulfides as a main ingredient, a solvent fractionation scheme was developed and applied to speciate As in the product. The metal content in the same TCM drug produced by different manufacturers was compared. The concentration of some metals such as Pb and Cd differs widely with different manufacturers, suggesting that their origin is primarily from external contamination. The high sensitivity and precision of the ICP-MS technique offers considerable advantages over conventional ICP-OES techniques for the analysis of complex samples such as TCM materials. Standardized analytic protocols based on ICP-MS are being developed fur the determination and characterization of metals and trace elements in TCM materials for product quality assessment.

    • Theory, design, and operation of a dynamic reaction cell for ICP-MS

      1999, 20(2):45-52. DOI: 10.46770/AS.1999.02.001

      Abstract (188) HTML (0) PDF 0.00 Byte (0) Comment (0) Favorites

      Abstract:Theory, design, and operation of a dynamic reaction cell for ICP-MS

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