Determination of As by UV-photochemical generation of its volatile species with AAS detection

Abstract

This work was focused on the development of an analytical method for determination of arsenic in liquid (aqueous solutions of arsenite) by UV-photochemical generation of its volatile compounds. The study contains the optimization, method characterisation and also a study of the influence of selected compounds on the signal measured. The method involves a combination of flow injection analysis, UV-photochemical generation of volatile compounds of arsenic in flow injection arrangement and atomic absorption spectrometry using an externally heated quartz tube atomizer. The attained absorbance was very low after the optimization. In the next step, the influence of selected compounds on UV-photochemical generation was investigated with the aim to find a suitable reaction modifier that would improve the sensitivity of arsenic determination. Bi(III) was found as the best reaction modifier not only for causing the increase of the signal of arsenic measured but also for its persisting effect. The activation with concentration of 10 mg dm−3 of Bi(III) increases the absorbance of arsenic approximately eleven times compared to signals without activation. Following method characteristics were achieved under the optimum experimental conditions: the limit of detection of 18 µg dm−3, the repeatability of 4.5 % expressed as % RSD at 200 µg dm−3, and linear dynamic range 60–500 µg dm−3 of arsenic.