Fractionation of arsenic in soil by a continuous-flow sequential extraction method

Batch sequential extraction techniques for fractionating metals or metalloids in soils are time consuming and subject to several potential errors. The development of a continuous-flow sequential extraction method for soil As is described and assessed, having the benefits of simplicity, rapidity, less risk of contamination, and less vulnerability to changes in extraction conditions compared with traditional batch methods. The validated method was used to fractionate soil As using water, NaHCO₃, NaOH, and HCl, followed by digestion of the residue with HNO₃, and HF acids. The extracts and digests were analyzed for As by graphite furnace atomic absorption spectrometry. Good recoveries of total soil As (97–115%) were obtained and fractionation data generally comparable with those obtained using conventional batch techniques. Soils from a tin-mining area in Thailand and soils from As-contaminated cattle (Bos taurus) dip sites in Australia were used to test the applicability of the method, and to demonstrate the usefulness of the extractogram obtained. The ability to produce detailed extractograms for As and other elements (Al, Fe, and Ca) enabled an examination of elemental associations in individual fractions. With the exception of As extracted with HCl, the extractograms generally support previous suggestions of the likely forms or associations of As present in the different soil fractions

Fractionation of arsenic in soil by a continuous-flow sequential extraction method

Batch sequential extraction techniques for fractionating metals or metalloids in soils are time consuming and subject to several potential errors. The development of a continuous-flow sequential extraction method for soil As is described and assessed, having the benefits of simplicity, rapidity, less risk of contamination, and less vulnerability to changes in extraction conditions compared with traditional batch methods. The validated method was used to fractionate soil As using water, NaHCO₃, NaOH, and HCl, followed by digestion of the residue with HNO₃, and HF acids. The extracts and digests were analyzed for As by graphite furnace atomic absorption spectrometry. Good recoveries of total soil As (97–115%) were obtained and fractionation data generally comparable with those obtained using conventional batch techniques. Soils from a tin-mining area in Thailand and soils from As-contaminated cattle (Bos taurus) dip sites in Australia were used to test the applicability of the method, and to demonstrate the usefulness of the extractogram obtained. The ability to produce detailed extractograms for As and other elements (Al, Fe, and Ca) enabled an examination of elemental associations in individual fractions. With the exception of As extracted with HCl, the extractograms generally support previous suggestions of the likely forms or associations of As present in the different soil fractions

Multielement analysis of petroleum samples by laser ablation double focusing sector field inductively coupled plasma mass spectrometry (LA-ICP MS)

International audienceA method was developed for the direct analysis of petroleum samples. A silica gel plate, commonly used in thin layer chromatography, was impregnated for 30 min with a sample solution and analyzed by laser ablation-ICP MS. The use of a doubly focusing sector field mass analyzer allowed the demonstration of the absence of carbon-related polyatomic interferences. Matrix suppression effects, common in nebulization-based sample introduction, were absent which enabled quantitation by external calibration. The detection limits were in the low ng g -1 range. The method was validated by the analysis of NIST 1084a and 1085b certified reference materials (wear metals in lubricating oils) and applied to the analysis of crude oil and asphaltene samples

Application of TLC and la ICP SF MS for speciation of S, Ni and v in petroleum samples

International audienceA coupling of thin layer chromatography with laser ablation ICP SF MS was developed for the fractionation of Ni, V, Fe and S in crude oil and its fractions (saturate, aromatic, resin and asphaltene). The detection limits were 18 ng g -1 and 23 ng g -1 for nickel and vanadium, respectively, and a sample could be characterized in terms of the metal distribution as a function of species polarity within 10 min. The method was used to characterize the metal distribution in crude oils of different origins and their different fractions. © 2012 Elsevier B.V. All rights reserved