Simple and useful method for determination of inorganic selenium species in real samples based on UV-VIS spectroscopy in a micellar medium

Abstract

A preconcentration and determination methodology utilizing the cloud point phenomenon was developed for the determination of inorganic selenium species using UV-VIS spectrophotometry. The cloud point extraction method was based on the selective formation of a complex between selenium(IV) ions and 4,5-diamino-6-hydroxy-2-mercapto pyrimidine (DAHMP). Then, the formed stable complex was extracted to a nonionic surfactant phase of Triton X-114. After phase separation was carried out via decantation, the surfactant-rich phase was diluted with 20% ethanol solution and the absorbance signal was measured at 458 nm using an UV-VIS spectrophotometer. Under the optimized conditions, linear calibration curves were obtained over a range of 20-1500 ng mL(-1) with detection and quantification limits of 6.06 ng mL(-1) and 19.89 ng mL(-1), respectively. The relative standard deviation was 2.80% for 5 replicate measurements at 250 mu g L-1 concentration level. The proposed method is very versatile and economic as only a conventional spectrophotometer is used for the measurements. The method was validated by the analysis of two certified reference materials and a recovery test. Finally, the method was applied to the determination of the total Se amount in real samples including water samples and hen eggs containing selenium.