Food Safety and Environmental Stewardship Program

Total arsenic, selenium, and antimony are determined simultaneously by inductively coupled plasma atomic emission spectrometry (ICP AES) with hydride vapor generation. A1 g wet, 0.25 g dry, or 10 mL water sample is digested by 1 of 2 methods in a 10 mL volumetric culture tube on a programmed heating block by heating with nitric acid and then boiling in a mixture of sulfuric and perchloric acids. For soils, a 0.25 g sample is digested in a 10 mL volumetric culture tube with hydrochloric acid. After digestion, the sample is treated with additional hydrochloric acid. Arsenic, selenium, and antimony are reduced to their hydrides by sodium borohydride in a simplified continuous- flow manifold. A standard pneumatic nebulizer separates the gaseous hydrides (AsH3, SeH2, and SbH3), which are then quantitated by ICP AES at 193.696,196.026, and 231.147 nm, respectively. The detection limits for As, Se, and Sb are 0.55,1.0, and 0.41 μg/L, respectively. Recoveries from 10 matrixes are 65 to 109%; recovery ranges for As, Se, and Sb are 81–109,87–108, and 65–123%, respectively. The method demonstrates good accuracy and precision for environmental samples and is especially suited for analysis of small samples. It requires no additional apparatus for hydride generation or sample introduction.