Spectrophotometric determination of Sb(III) in Sb(III)/Sb(V) binary mixtures using sodium dodecylsulfateonylphenoxy polyethoxyethanol mixed micellar media

摘要

Different micellar media had different effects on the absorption spectra of the complexes of bromopyrogallol red with Sb(III) and Sb(V). The mixed micellar medium composed of 0.7 ml of 0.2% sodium dodecylsulfate (SDS) and 0.3 ml of 2% nonylphenoxypolyethoxyethanol (OP) at 80°C could be used for the sensitive determination of Sb(III) in Sb(lII)/Sb(V) binary mixtures. Under the optimal conditions. Beer's Law was obeyed over the range 0.1-2.3 μg ml~(-1) Sb(III) with molar absorptivity at 538 nm being4.8 x 10~4 1 mol~(-1) cm~(-1) and detection limit 0.04 μg ml~(-1). For 10 μg Sb(IIl). more than 100 ug Sb(V) could be tolerated (error < 3%) in the presence of SDS/OP micellar medium as compared with 0.1 μg Sb(V) in the absence of SDS OP micellar medium. In addition, the sensitivity of Sb(III) in the micellar medium was much higher than that in pure water medium. As compared with conventional extraction spectrometry, the proposed method produced a reproducible result. It did not need the conversion of Sb(IlI) to Sb(V) and a time-consuming extraction process. A detailed discussion on the selection of surfactants, the effect of temperature, and the role played by the mixed surfactants were also made.