Investigation of Poor Analytical Recovery Using Borosilicate Glass Containers in Selenium Determination by Atomic Absorption Spectrometry with Hydride Generation

The chemical interferences of Hg2+, Sn4+, Pb2+, Fe3+, Bi3+, and Te4+ in the hydride generation atomic absorption spectrometry (HG-AAS) determination of selenium have been studied but interference from the glassware commonly used in these analyses has not been systematically determined. When a glass test tube, which was employed to prepare selenium samples in the required Se(IV) oxidation state for HG-AAS, was used without proper pretreatment it caused a large negative interference in selenium analysis (10-90%). In this study, we have quantitatively determined the magnitude of interferences caused by borosilicate glassware in HG-AAS selenium analysis. A series of glass pretreatments were also evaluated to remove or minimize those interferences. We found that treating glass test tubes with concentrated nitric acid prior to the sample preparation, resulted in the highest recovery of selenium compared to separate pretreatments of either distilled water, a commercial laboratory detergent, aqua regia, chromic acid, or concentrated hydrochloric or sulfuric acids. Surprisingly, HCl pretreatment resulted in the lowest average recovery rate of all the methods of pretreatment examined