Selenium determination in volcanic soils by ICP-QMS: influence of reaction cell pressurization and methanol addition on the occurrence of spectral interferences

Abstract

Accurate determination of selenium in soils is a critical issue in geochemistry, because Se has a narrow range between dietary deficiency and toxic concentrations. However, its determination is difficult as Se commonly occurs at low levels. Se measurements by ICP-MS are hampered by Ar-based polyatomic ions overlapping Se isotopes. Moreover, in complex matrixes such as geological materials, additional spectral interferences might occur. In this work spectral inferences in volcanic soil digestions have been assessed using both synthetic solutions and real samples under four different measurement conditions that include the addition of an organic solvent (methanol) and the use of a pressurized octopole system. The results indicate that the traditional approach using 82 Se without collision-reaction cell significantly overestimates the Se concentration. With the use of a hydrogen pressurized collision-reaction cell an interference-free 78 Se signal could be obtained. Methanol was found to decrease the effect of interferences and additionally improves the count statistics due to higher sensitivity. Correspondingly, the best results were obtained using 78 Se with a hydrogen pressurized collision-reaction cell and a 2% methanol matrix.

Applicability of direct total reflection X-ray fluorescence analysis for selenium determination in solutions related to environmental and geochemical studies

“…The Se measurements were performed with a hydrogen pressurized cell (3.5 mL/min) detecting 78 Se and using 103 Rh as internal standard. To decrease the effect of interferences and to improve the sensitivity for Se determination, methanol (~2%) was added to standards and sample aliquots [20,21]. The plasma was operated with 1.5 kW with 15 L min − 1 plasma gas and~1.0 aerosol L min − 1 carrier gas.…”

Atomic spectrometry update. Environmental analysis

“…Sahoo et al 233 avoided this problem in their study of soils from Chernobyl by measuring 127 77 Se since it could not resolve 80 Se from the interferent. Floor et al 237 applied a collision cell in the analysis of volcanic soils. Best results were obtained by the addition of ca.…”

Selenium mobilization in soils due to volcanic derived acid rain: An example from Mt Etna volcano, Sicily

“…Both samples and standard were measured in a matrix of 2% methanol (MeOH N99.9% pure, chromosolv plus, Sigma-Aldrich) added prior to analyses in order to increase sensitivity (Floor et al, 2009). To compensate for matrix effects Rh was added as internal standard.…”

“…Total soil Se content was obtained by ICP-MS analyses following microwave digestion (Floor et al, 2009). The total major element content in the soil samples was determined by X-Ray Fluorescence (XRF, Actlab laboratories Canada).…”