Flow analysis-hydride generation-Fourier transform infrared spectrometric determination of antimony in pharmaceuticals

摘要

In this work, a flow analysis system with hydride generation and Fourier transform infrared (FTIR) spectrometric detection has been developed for the determination of antimony in pharmaceuticals. The method is based on the on-line mineralization/oxidation of the organic antimonials present in the sample and pre-reduction of Sb(V) to Sb(III) with K_2S_2O_8 and KI, respectively: prior to the stibine generation. The gaseous SbH_3 is separated from the solution in a gas phase separator, and transported by means of a nitrogen carrier into a short pathway (10 cm) IR gas cell, where the corresponding FTIR spectrum is acquired by accumulating 3 scans in a continuous mode. The 1893 cm~(-1) band was used for the quantification of the antimony. The procedure is carried out in a closed system, which reduces sample handling and makes possible the complete automation of the antimony determination. The figures of merit of the proposed method (linear range: 0-600 mg l~(-1), limit of detection (3σ) = 0.9 mg l~(-1), limit of quantification (10σ) = 3 mg Sb l~(-1), precision (R.S.D.) less than 1% and sample frequency = 28 h~(-1)), are appropriate for the designed application. Furthermore, precise and accurate results were found for the analysis of different antimonial pharmaceutical samples, indicating that the methodology developed represents a valid alternative for the determination of antimony in pharmaceuticals, which could be suitable for the routine control analysis.