Speciation without chromatography: Part 2. Determination of tributyltin by chloride generation flow injection atomic absorption spectrometry

A procedure is described for the quantitation of tributyltin in aqueous samples and extracts based on its relatively high volatility in halide media, permitting vapour phase sampling from the headspace above such samples.Tributyltin chloride (TBT-C1) was purged from various chloride containing aqueous matrices and collected on the surface of an iridium treated graphite tube for subsequent quantitation by graphite furnace atomic absorption. Iodide, bromide and chloride matrices were compared for their generation efficiency. The effect of acidity of the sample was also studied. An absolute detection limit of 1.3 ng TBT (as tin) was estimated, corresponding to a detection limit of 0.33 ng ml 1 for a 4 ml sub-sample. Method validation was achieved using NRCC PACS-2 (sediment) Certified Reference Material, for which reasonable agreement between certified and measured values of tributyltin content was obtained. A procedural concentration limit of detection of 66 ng g 1 TBT in the sediment could be achieved

Evaluation of Sample Preparation Procedures for Determination of Cr(VI) in Cr 2 O 3 Pigments by Vis Spectrophotometry

Abstract Six sample preparation procedures were evaluated for selective extraction of Cr(VI) from commercial samples of chromium oxide green (Cr2O3) pigments prior to formation of its diphenylcarbazone complex [CrDPCO]- for determination by visible spectrophotometry: (I) water-soluble chromium; (II) EPA method 3060A without Mg2+; (III) EPA method 3060A with Mg2+; (IV) Na3PO4 based extraction; (V) method IRSA16 based on acidic extraction and; (VI) Na2CO3 based extraction. Evaluation of the influence of concomitant Cr(III) ions, time and stability of the [CrDPCO]- complex was investigated. Recoveries of soluble and insoluble Cr(VI) species were 86% and 80%, respectively, using procedure (VI). Direct calibration against aqueous standards prepared in the extraction medium was successful for Cr(VI) in the concentration range 0.05-1.50 μg L-1. Limits of detection and quantitation were 0.3 µg g-1 and 1.0 µg g-1, respectively, for 250 mg subsamples/25 mL. Procedure (VI) was applied to the analysis of four commercial samples of Cr2O3 pigments, three determined to have Cr(VI) within compliance limits below 1.0 µg g-1, but one at 16.6 ± 0.6 µg g-1, prohibiting use of this pigment in cosmetic formulations. This sample was conveniently employed to evaluate the accuracy of the method. The recommended procedure is simple and accurate and has been adopted by Tecpar's laboratory of Parana Institute of Technology (Curitiba, Brazil)

Social Skills and Psychological Disorders: Converging and Criterion-Related Validity for YSR and IHSA-Del-Prette in Adolescents at Risk

This study evaluated indexes of converging and criterion-related validity for the Social Skills Inventory for Adolescents (IHSA-Del-Prette) and the Youth Self-Report (YSR) in two samples: one referring to clinical service (CLIN), with 28 adolescents (64.3% boys), 11 through 17 years old (M = 13.75; SD = 1.74), and the other referring to a psycho-educational program (PME = 46.2%), mainly composed of boys (91.7%) aged 13 through 17 (M = 15.33; SD = 1.47). Both samples completed the two inventories. Results showed a high incidence of psychological disorders in both samples (between 4% and 79% in the borderline or clinical range on YSR scales) and accentuated deficits in the general and subscale scores of IHSA-Del-Prette, especially on the frequency scale (25% to 58%). The correlations between the instruments in the two groups supported criterion-related and converging validity. Some issues concerning the differences between the samples and about the construct of social competence, underlying these inventories, are discussed. Key words authors

Detection of bromine by ICP-oa-ToF-MS following photochemical vapor generation

A unique flow-through photochemical reactor is utilized for the generation of volatile methyl bromide from aqueous solutions of bromide and bromate ions in a medium of 2% acetic acid containing 3000 \u3bcg/mL NH4Cl. The volatile product is transported to a thin-film gas-liquid phase separator and directed to an inductively coupled plasma (ICP) tine-of-flight mass spectrometer for detection and quantitation using either of the 79Br or 81Br isotopes. Utilizing a sample flow rate of 3.3 mL/min and a 13 s irradiation time, a detection limit of 0.14 ng/mL is achieved, yielding a 17-fold enhancement over conventional solution nebulization. The estimated generation efficiency of 95% provides for a significant increase in analyte transport efficiency to the ICP. Precision of replicate measurement is 2.5% (RSD) at 20 ng/mL. The methodology was validated by successful determination of bromine in reference materials, including IRMM (BCR-611) low level bromide in groundwater, NIST SRM 1568b Rice Flour, and SRM 1632 bituminous coal.Peer reviewed: YesNRC publication: Ye

High accuracy and precision isotope dilution mass spectrometry: an application to the determination of Mo in seawater

Two isotope dilution calibration approaches, a standard two-step and a curve method, were examined in an effort to achieve highest accuracy and precision for determination of Mo in seawater. On-line matrix separation using immobilized 8-hydroxyquinoline permitted transient measurements to be made by both sector field sequential (SF-ICP-MS) and multicollector (MC-ICP-MS) inductively coupled plasma mass spectrometry. Concentrations of 9.42 \ub1 0.22 and 9.396 \ub1 0.053 ng g 12\ub9Mo (U, 95% confidence interval, k = 3.18, n = 4) were obtained in NASS-5 seawater using the standard two-step ID method with SF-ICP-MS and MC-ICP-MS, respectively, in good agreement with the certified value of 9.4 \ub1 1.0 ng g 12\ub9 (U, 95% confidence interval, k = 2; concentration converted from ng ml 121 to ng g 12\ub9). A 4-fold enhancement in the precision of determination was evident using MC-ICP-MS. Performance of the standard two-step ID and the ID curve method was also compared following an off-line column separation which permitted steady-state solution nebulization with MC-ICP-MS detection. Undertaking mass bias drift correction during a measurement sequence generated identical concentrations of 9.383 \ub1 0.016 and 9.383 \ub1 0.014 ng g 12\ub9Mo (U, 95% confidence interval, k = 3.18, n = 4) in NASS-5 using the two-step ID and the ID curve method, respectively, despite significant blank correction arising from the off-line column separation which amounted to 4\u20135% of the total Mo in the sample. Although the ID curve method uses an additional set of reverse ID calibration solutions, it benefits from the advantages of not needing to employ a certified isotopic reference material for mass bias correction or to know isotope abundances of the analyte in the sample, the standard or the enriched spike. An analysis of the sources of uncertainty suggests that the contribution from determination of the ratio is no longer dominant. Further improvements below 0.1% could be achieved by optimizing other sources of uncertainties, such as increasing the masses of enriched spike and natural abundance Mo standard solutions as well as the mass of high purity Mo standard used for its preparation, assuming similar measurement precision for the ratios and the same number of replicate samples measured.Peer reviewed: YesNRC publication: Ye

Liquid cooling of a torch for microwave induced plasma spectrometry

A simple torch design for use with a microwave induced plasma (MIP) is described that can be internally cooled by synthetic or hydrocarbon based fluids. The MIP is generated within a liquid coolant-cooled concentric quartz discharge torch, energized within a novel microwave plasma cavity. Erosion of the discharge tube by the plasma, assessed by measurement of the emission intensity of ablated silicon, is essentially eliminated. The emission spectra of the liquid-cooled plasmas are compared to those sustained in uncooled discharge tubes.Peer reviewed: YesNRC publication: Ye