Rapid determination of arsenic in copper and brass by neutron-activation analysis

Abstract

A rapid neutron-activation analysis method is presented for the determination of microgram amounts of arsenic in copper and brass. Neutronirradiated samples are dissolved in hot perchloric acid in the presence of an arsenic carrier. The resulting solution is made 7·4 M with respect to perchloric acid and 1·2 M with respect to hydrobromic acid. The arsenic-76 and the arsenic carrier are extracted quantitatively into benzene. After washing the benzene layer with 7·4 M perchloric acid-1·2 M hydrobromic acid mixture, arsenic-76 is counted directly in the organic phase. The radio-chemical purity of the arsenic-76 extract was demonstrated by using a multi-channel analyser, together with decay studies. After the irradiation, the time required to complete the analysis is less than 15 minutes, which is at least four times shorter than that previously reported for activation analysis methods.

The proposed method was successfully applied to the determination of arsenic in copper and brass primer cups and primer pockets (arsenic content 1 to 50 p.p.m.).