Determination of As and Sb in mineral waters by fast sequential continuous flow hydride generation atomic absorption spectrometry

Abstract

In this study, a novel analytical method which consists of a combination of Fast Sequential Flame Atomic Absorption Spectrometry (FS-FAAS) and Continuous Flow Hydride Generation Atomic Absorption Spectrometry (CF-HGAAS) is proposed. The method developed was employed for the sequential determination of As and Sb at sub-μg L⁻¹ levels in bottled mineral waters. A strong enhancement in the analytical throughput was obtained when compared with the traditional mono-element CF-HGAAS with a quartz tube atomizer (QTA). Variables which would affect the method performance such as Ar flow rate, HCl and NaBH₄ concentrations as well as delay and integration time were optimized. A flame atomic absorption spectrometer working in fast sequential mode was used in all experiments. After just 20 s of read delay, As and Sb were sequentially determined in 6 s (3 s each element). A 2⁶⁻² fractional factorial design was employed for studies of potential interferents with transition metals that could be present in mineral water samples. Limits of detection obtained for As and Sb were 0.15 and 0.14 μg L⁻¹, respectively. The accuracy of the proposed method was checked by the use of 2 certified reference materials: Trace elements in water (NIST 1643e) and Trace metals in drinking water (HPS TMDW). Good agreement between certified and found concentrations was observed. Finally, As and Sb were determined in commercial bottled mineral water samples. Adequate sensitivity, high throughput and minimization of reagents and sample consumption are the attractive features of this new method.