Merging zones flow injection for the determination of ultratraces of bismuth by volatile species generation atomic absorption spectrometry using sodium tetraethylborate(III)

The generation of a volatile Bi compound by its reaction in aqueous solution with sodium tetraethylborate(iii) has been achieved using a flow injection (FI) system with injection of Bi and NaBEt₄ solutions in a ‘merging zones’ mode. This vapour generation (VG) system has been successfully interfaced with an atomic absorption spectrometric (AAS) detector for the determination of low levels of the metal. A detection limit of 0.8 μg l⁻¹ (0.56 ng) of Bi was obtained after optimization of the chemical and instrumental parameters. This volatile species generation with AAS detection showed a precision of ±2.9% at the 40 μg l⁻¹ level of Bi and a sample throughput of about 100 samples h⁻¹ was observed. Interference studies were carried out for many potentially interfering elements. The proposed FI–VG-AAS method proved to be very selective for the determination of Bi and so it has been successfully applied to the determination of ultratraces of Bi in human urine after simple 1+1 dilution without any other preteatment; the detection limit in real urine samples was 1.6 μg l⁻¹. Bismuth recoveries of 100% were found in spiked urine samples and also excellent agreement was achieved between results obtained by FI–VG-AAS and those obtained by ICP-MS for real urine samples. Finally, the proposed procedure was applied to the study of urinary clearance of Bi in three different people after intake, at therapeutic doses, of colloidal Bi subcitrate (CBS).