Comparison of systems for eliminating interferences in the determination of arsenic and antimony by hydride generation inductively coupled plasma atomic emission spectrometry

The determination of arsenic and antimony by hydride generation inductively coupled plasma atomic emission spectrometry is discussed. A comparison is made of different procedures for eliminating redox (HNO3) and transition metal interferences; two pre-reduction agents, three continuous-flow systems and two gas–liquid separators were studied. The pre-reduction agents were KI and thiourea, which were added in a continuos-flow mode either before or after the introduction of tetrahydroborate. The spray chamber served as a gas–liquid separator; alternatively a U-tube separator was used. In the recommended system, 10% m/v thiourea is added to the sample stream before 1.0% m/v tetrahydroborate is introduced, using the spray chamber as a gas–liquid separator. Thiourea eliminated the oxidation interference from HNO3 and also the interference from 50 mg l–1 of Ag+, Cu2+, Ni2+ and Fe3+.