The effect of six reaction media on the determination of bismuth at trace levels in environmental samples by hydride generation and inductively coupled plasma-atomic emission spectrometry

Abstract

An investigation was carried out to explore the effect of hydrochloric, tartaric, citric, oxalic, acetic and sulfosalicylic acids on the hydride generation of Bi at trace levels in a continuous flow system in conjunction with inductively coupled plasma atomic emission spectrometric detection. The operating conditions (chemical and physical parameters) and the concentrations of the acids studied were evaluated for the efficient generation of BiH₃ (bismuthine). Kinetic information about the decomposition process of BiH₃ was also obtained. Analytical figures of merit including detection limits, precision and linear dynamic ranges are given for the six acids employed. The detection limits for Bi ranged between 0.3 and 0.7 µg l^–1 depending on the acid used to generate BiH₃. Compared with conventional continuous nebulization, the present coupling gives a sensitivity increase of approximately two orders of magnitude. The interfering effect of transition metals (Cd, Co, Cu, Cr, Fe, Mn, Ni, Zn), other hydride-forming elements (As, Ge, Pb, Sb, Se, Sn, Te) and Hg on the Bi signal using the different acids studied was evaluated. Tartaric acid is the most suitable reaction medium, in terms of efficiency in the hydride generation process and in the control of interferences. The proposed method was applied to the determination of Bi in certified reference materials (fresh water, silicate) and real environmental samples (iron ore and coal fly ash).