A simple and sensitive flow-injection on-line preconcentration coupled with hydride generation atomic fluorescence spectrometry for the determination of ultra-trace lead in water, wine, and rice.

A simple and sensitive flow-injection on-line separation and preconcentration system coupled to hydride generation atomic fluorescence spectrometry (HG-AFS) was developed for ultra-trace lead determination in water, wine, and rice samples, with the salient advantages of its minimization of transition-metal interferences and tolerance to an ethanol matrix. A lead hydroxide precipitate was achieved by the on-line merging of a sample and an ammonium buffer solution and collected onto the inner walls of a knotted reactor (KR). Removal of the residual solution from KR was achieved by air flow, and dissolution of the precipitate was carried out by using 0.2 mol l-1 HCl. With a sample consumption of 11.7 ml, an enhancement factor of 16 was obtained at a sample throughput of 30 h-1. The limit of detection (3s) was 16 ng l-1 and the precision (RSD) for 1.0 µg l-1 Pb was 3.4%.