Atomic absorption spectrometric determination of arsenic and selenium in offal and fish by hydride generation

A method for determining As and Se in beef offal and fish was developed. The sample was digested by heating with a mixture of nitric, perchloric, and sulfuric acids. No pre-reduction of As and Se was necessary. Using a simplified generator, the metal hydrides were evolved by reduction with sodium borohydride pellets from sulfuric and hydrochloric acid media. The hydrides were swept by a flow of nitrogen into a nitrogen-hydrogen-entrained air flame. Absolute detection limit of the method was about 6 ng for As and 4 ng for Se, and absolute sensitivity for both metals was estimated to be 5 ng. Effects of the presence of several cations and anions in the matrix were investigated and some were found to have a suppressive effect on the atomic absorption signal. The analytical results obtained for samples of NBS No. 1571 Orchard Leaves and NBS No. 1577 Bovine Liver agreed well with certified values.