Determination of bismuth in pharmaceutical products using liquid–liquid extraction in a flow injection system

Abstract

A flow injection procedure for the determination of bismuth in pharmaceutical products is described. The procedure is based on the formation of an ion-pair between tetraphenylarsonium and the tetraiodobismuthate(III) anion. This ion-pair is extracted with chloroform and the absorbance of the organic phase is measured at 363 or 505 nm. The detection limit (3×baseline s.d.) is 1.5 × 10 −6 M (35 ng). The proposed procedure has a relative standard deviation of 1.6% (3.0 × 10 −5 M, n = 12), a linear application range between 2.3 × 10 −6 and 1.5 × 10 −4 M and a sampling frequency of 40 h −1. Under the proposed working conditions, only Pd(II), Pt(IV) and Au(III) interfere.