A sequential injection lab-at-valve (SI-LAV) platform for hydride generation atomic absorption spectrometry (HG-AAS): on-line determination of inorganic arsenic

Abstract

A novel automatic low-cost sequential injection lab-at-valve (SIA-LAV) system has been developed for inorganic arsenic determination coupled with hydride generation atomic absorption spectrometry (HG-AAS). The proposed manifold includes an integrated gas–liquid separator/reaction chamber (GLS-RC) which was attached to one port of a conventional six-port multiposition selection valve. The arsine vapour is generated by injecting reductant NaBH₄ into the GLS-RC, minimizing its dispersion and possible losses. All critical parameters affecting the efficiency of the system were studied and optimised. For 3.0 mL sample consumption the detection limit was 0.05 μg L⁻¹ and the precision expressed as RSD was 3.2%. The proposed method was evaluated in comparison with a reference flow injection HG method and applied for arsenic determination in environmental water samples. The recovery was estimated by spiking the samples and it ranged from 95.5% up to 102.5% for both As(III) and As(V).