Selective determination of Sb(III) in drugs by flow injection hydride generation AAS

In this work, a procedure is described for the selective determination of Sb(III) in commercial drugs based on pentavalent antimony. Antimony(III) was determined by flow injection atomic absorption spectrometry (FI-HG-AAS) in drugs injected for leishmaniasis treatment in South America. The following acids were studied: acetic, tartaric, citric, oxalic, and lactic. The optimized conditions for Sb(III) determination without interference from Sb(V) were: 20% (m/v) citric acid, 2.0% (m/v) sodium tetrahydroborate, 125 muL injection volume, and 180 cm for reactor length. Interference of As, Ni, and Pb on the Sb(III) analytical signal was also investigated. The detection limit was 0.95 ng and the characteristic mass 55 pg. The recovery values obtained using the proposed procedure for six commercial samples varied from 97.1-100.8%. The relative standard deviation was 3.8%. The proposed FI-HG-AAS procedure allows more than 60 determinations per hour. The optimized procedure was applied for quality control of pentavalent antimony-based drugs produced commercially in Brazil.