Determination of Selenium(IV) by Electrothermal Atomic Absorption Spectrometry using Single Drop Extraction in Real Samples

Abstract

In this investigation, two new chemical modifiers for determination of Se(IV) are reported. The first, is coating of Pd in graphite tube and injection of Pd solution on top of sample solution in tube ([Pd_(c) + Pd_(i)]). Second modifier is concurrent coating with each of W, Rh and Pd in graphite tube ([W.Rh.Pd]_(c)). These modifiers showed very low detection limits, higher sensitivity and longer lived than other modifiers previously adapted for selenium. Second modifier is useful for determination of Se(IV) in inorganic compounds. For obtaining higher sensitivity method of single drop extraction for determination of trace amounts of selenium is reported. In this method Se (IV) is reacted with o-phenylenediamine, the piasoselenol complex formed was then extracted into micro drop of 1,2 dichloroethane. After extraction, the micro drop was retracted and directly transferred into a graphite tube modified by [Pd_(c) + Pd_(i)]. The detection limit was calculated to be 0.8 ng/mL (absolute value of 0.3 ng) based on 3S_b. The relative standard deviation for five replicate analysis of 10 ng/mL Se was 4.8 %. The calibration curve was linear in the range of 0.8 to 40 ng/mL with a sensitivity of 0.25 ng/mL. Recovery of the method was 96 % for tap water spiked with selenium. In order to evaluate the applicability of the method, the amount of Se(IV) in plants, sea water and milk was determined.