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Quantitative Recovery (quantitative + recovery)

Distribution by Scientific Domains

Chemistry	50%

Selected Abstracts

Quantitative Recovery of Elemental Sulfur and Improved Selectivity in a Chromium-Reducible Sulfur Distillation

GEOSTANDARDS & GEOANALYTICAL RESEARCH, Issue 1 2009
Jens Gröger
soufre réductible par le chrome; CRS; soufre élémentaire; selectivité; efficacité de distillation Chromium-reducible sulfur (CRS) distillations are intended to recover only reduced inorganic sulfur compounds (RIS) including elemental sulfur. However, the quantitative recovery of elemental sulfur is not ensured in common CRS-distillations. The new method presented here was designed to remedy this deficiency. An increase in ethanol concentration assured the quantitative recovery of elemental sulfur in various forms and, in addition, all other RIS-compounds were quantitatively recovered. Furthermore, the selectivity of the procedure was improved by an additional filtration step to eliminate zinc particles from the Cr(II)-solution. Thus, the recovery of sulfates and organic sulfur compounds was significantly decreased by a factor of up to 35, depending on the compound analysed. Exhaustive testing with a variety of pure phases, rock and soil samples demonstrated the precision and accuracy of the new method. The new protocol eliminated the constraints of previous procedures. The improved distillation efficiency for elemental sulfur ensured the quantitative recovery of all RIS-compounds in a single-step distillation. Des distillations du soufre réductible par le chrome (CRS) ont été effectuées afin de récupérer uniquement les composés soufrés inorganiques (RIS: reduced inorganic sulfures) dont le soufre élémentaire. La procédure classique de distillation CRS ne permet pas néanmoins la récupération totale du soufre élémentaire. Une nouvelle méthode, présentée ici, a été développée pour remédier à ce problème. L'augmentation de la concentration en éthanol assure la récupération totale du soufre élémentaire sous différentes formes et, de plus, celle de tous les autres composés RIS. La sélectivité de la procédure a été améliorée par l'ajout d'une étape de filtration, qui élimine des particules de zinc provenant de la solution Cr(II). Ceci a entraîné une diminution jusqu'à un facteur 35 du taux d'extraction des sulfates et des composés soufrés organiques, selon les composés analysés. Des tests extensifs sur différentes phases pures et des échantillons de roches et de sols ont montré la précision et la justesse de cette nouvelle méthode. Le nouveau protocole élimine les contraintes des procédures passées. L'amélioration de l'efficacité de cette distillation concernant le soufre élémentaire garantit une récupération fiable de tous les composés RIS par une distillation en une seule étape. [source]

Determination of total urinary mercury by on-line sample microwave digestion followed by flow injection cold vapour inductively coupled plasma mass spectrometry or atomic absorption spectrometry

RAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 15 2002
M. Bettinelli
The total mercury content in urine was determined by inductively coupled plasma mass spectrometry with the so-called cold vapour method after on-line oxidative treatment of the sample in a microwave oven (FI-MW-CV-ICPMS). Use of a KBr/KBrO3 mixture, microwave digestion, and the final oxidation with KMnO4, assure the complete recovery of the organic forms of Hg which would be difficult to determine otherwise if using only the CV-ICPMS apparatus. Quantitative recoveries were obtained for phenyl Hg chloride (PMC), dimethyl Hg (DMM), Hg acetate (MA) and methyl Hg chloride (MMC). Use of automatic flow injection microwave systems (FI-MW) for sample treatment reduces environmental contamination and allows detection limits suitable for the determination of reference values. Since no certified reference materials were commercially available in the concentration ranges of interest, the accuracy of the proposed procedure has been assessed by analysing a series of urine samples with two independent techniques, ICP-MS and AAS. When using the FI-MW-CV-ICP-MS technique, the detection limit was assessed at 0.03µg/L Hg, while with FI-MW-CV-AAS it was 0.2µg/L Hg. The precision of the method was less than 2,3% for FI-MW-CV-ICP-MS and about 3,5% for FI-MV-CV-AAS at concentrations below 1µg/L Hg. These results show that ICP-MS can be considered as a "reference technique" for the determination of total urinary Hg at very low concentrations, such as are present in non-exposed subjects. Copyright © 2002 John Wiley & Sons, Ltd. [source]

Quantitative Recovery of Elemental Sulfur and Improved Selectivity in a Chromium-Reducible Sulfur Distillation

Molecularly imprinted polymers for selective analysis of chemical warfare surrogate and nuclear signature compounds in complex matrices

JOURNAL OF SEPARATION SCIENCE, JSS, Issue 11 2005
Scott D. Harvey
Abstract This paper describes the preparation and evaluation of molecularly imprinted polymers (MIPs) that display specificity toward diisopropyl methylphosphonate (DIMP) and tributyl phosphate (TBP). Polymer activity was assessed by solid-phase extraction and high-performance liquid chromatography experiments. Both DIMP- and TBP-specific vinylpyridine-based MIPs selectively retained their targets relative to a non-imprinted control. Proof-of-principle experiments demonstrated highly selective analysis of the targets from fortified complex matrix samples (diesel fuel, gasoline, and air extract concentrate). The retained MIP fractions gave near quantitative recovery of the target analytes with very low matrix background content. The same fraction from the control sorbent recovered only about half of the analyte and tended to be less pure. [source]