Simultaneous speciation of redox species of arsenic and selenium using an anion-exchange microbore column coupled with a micro-concentric nebulizer and an inductively coupled plasma mass spectrometer as detector

Abstract

Speciation methods for trace metals in the environment need rapid and accurate analyses. The simultaneous determination of redox species of arsenic (As^III and As^V) and selenium (Se^IV and Se^VI) has been carried out by coupling a microbore column with a micro-concentric nebulizer (MCN) and inductively coupled plasma mass spectrometry (ICP-MS). The MCN, with its ability to nebulize liquids at low flow rates, was adapted to a small bore (2 mm id) microbore anion-exchange column. After optimizing the parameters of the MCN by factorial experimental design, an evaluation of the separation of redox As and Se species was carried out. The method was applied to the determination of the four species in a sample recommended for Se speciation studies, in a spiked natural water and in polluted soil leachings. No interference of ⁴⁰Ar³⁵Cl on ⁷⁵As was observed when natural water samples were analyzed. The method showed good accuracy and repeatability in addition to facile handling and development. A detection limit of 1 ng ml^–1 was found for the arsenic species and 4 ng ml^–1 for the selenium species.