Abstract :
A hydride generation method for the determination of traces of selenium at ng mL^-1 concentration ranges has been introduced using a solid mixture of tartaric acid and sodium tetrahydroborate. Atomic absorption spectrometry (AAS) has been used as the detection system. Several parameters such as the ratio of tartaric acid to sodium tetrahydroborate, type and amount of acid, and the reaction temperature were optimized by using 640 ng mL^-1 (16 ng per 25 (mu)L) of Se(IV) standard solution. The calibration curve was linear from 20 to 1200 ng mL^-1 (0.5-30 ng Se(IV) per 25 (mu)L). The relative standard deviation (%R.S.D.) of the determination was 1.93% and the detection limit was 10.6 ng mL^-1 (265 pg per 25 (mu)L) of Se(IV). The reliability of the method was checked using different types of environmental samples, such as several types of water, a sample of soil and also in a kind of calcium phosphate sample by standard addition method. For conversion of Se(VI) present in real samples to Se(IV), L-cysteine was added to NaBH4 and tartaric acid mixture. The results showed good agreement between this method and other hydride generation techniques.
