Sensitization of stibine generation: antimony determination in environmental samples by atomic fluorescence spectrometry

Abstract

This paper reports an improvement in the efficiency and selectivity of stibine generation and therefore an improvement in the analytical characteristics for antimony determination in environmental matrices by atomic fluorescence. The sensitized method is achieved by generating the stibine at 70 °C and using additional hydrogen flow to sustain the atomization flame, which makes it possible to reduce the acid and borohydride concentration and therefore to economize the process and reduce the inherent pollution risks due to the high concentrations used. Furthermore, a new phase separator in which temperature is controlled and dead time significantly reduced has been designed and incorporated in the hydride generation system. Selectivity is increased by working in an organized medium, Triton X-100 being the surfactant chosen as the most appropriate. Under the optimized conditions, a limit of detection of 0.3 µg l^–1 of Sb was achieved, with a precision of 1.4% for 8 µg l^–1 , and the calibration graph was linear from 0.3 to 2.7×10³ µg l^–1 . The sensitized method performed satisfactorily when evaluated by the determination of Sb in standard reference material (SRM 1648) of atmospheric urban particulate matter and by recovery studies in sea-water, tap water and in air samples collected on silica filters. The recovery in the enriched samples was 99±1% in all cases. The proposed method was successfully applied to the determination of Sb in samples of Bilbao urban air, being 13.2±0.3 ng m^–3 , the antimony concentration found.