Speciation of Arsenic(III)/Arsenic(V) and Selenium(IV)/Selenium(VI) Using Coupled Ion Chromatography– Hydride Generation Atomic Absorption Spectrometry

Simple analytical methods have been developed to speciate inorganic As and Se in the microgram per liter range using coupled ion chromatography–hydride generation atomic absorption spectrometry. Because of the differences in toxicity and adsorption behavior, determinations of the redox states arsenite, As(III), and arsenate, As(V), and selenite, Se(IV), and selenate, Se(VI), are important. Anion exchange chromatography is used to separate As(III) and As(V) or Se(IV) and Se(VI) based on differences in retention times. Samples are then mixed with concentrated HCl for As or Se determination as the hydrides. Detection limits are 0.8 mg L−1 As for both redox states, 0.68 mg L−1 for Se(IV), and 0.55 mg L−1 for Se(VI). Spiking of actual mixed sample solutions of both redox states showed the procedure to be accurate for solutions with As(III)/As(V) or Se(IV)/Se(VI) ratios ranging from 1:4 to 4:1. Average recoveries were 95.7% for As (III), 106% for As(V), 93.1% for Se(IV), and 108% for Se(VI). The technique can be used to determine As(III) and As(V) and Se(IV) and Se(VI) in deionized water and actual and synthetic irrigation waters. Abbreviations: EC, electrical conductivity; HGAAS, hydride generation atomic absorption spectrometry; HPLC, high performance liquid chromatography; NIST, National Institute of Standards and Technology; SRM, standard reference material. Published 2013