Total reflection X-ray fluorescence selenium analysis after reduction and quartz reflector adsorption

Selenium can be reduced by suitable reagents to give a colloid suspension; this suspension can be adsorbed on quartz surfaces and analyzed by X-ray fluorescence. In the present work a new method for the determination of trace levels of selenium is developed. Se(IV) was collected on TXRF-reflectors after reduction with ascorbic acid. More specifically, the reflectors were immersed in water solutions containing low concentrations of Se(IV); reductive agents were added and colloid selenium was prepared. After the end of the colloid adsorption on the reflectors' surfaces, they were removed, cleaned with pure water, desiccated and analyzed with total reflection X-ray fluorescence (TXRF). The effects of various experimental parameters were examined. The coexistence of other metals does not interfere in the analysis process and the method can be applied in various types of waters, including seawater. The minimum detection limit was 0.8 ng mL−1.