A simple sample preparation procedure for the fast screening of selenium species in soil samples using alkaline extraction and hydride-generation graphite furnace atomic absorption spectrometry

This work proposes a simple procedure for the determination of selenium species in soil samples using an ultrasound-assisted alkaline extraction and hydride generation atomic absorption spectrometry (HG AAS), which is known to be specific for the determination of Se(IV) only. The hydride was trapped and atomized in a graphite tube furnace (GF) coated with iridium as a permanent chemical modifier. The limits of detection and quantification for the developed method were 6 μg L− 1 and 20 μg L− 1 Se(IV), respectively, with a linear range between 20 and 100 μg L− 1, and a linear coefficient of R = 0.999. The total Se content in the samples was determined in the alkaline extract using high-resolution continuum source GF AAS (HR-CS GF AAS), and the content of Se(VI) was determined by difference between the total Se and the content of Se(IV). The extraction efficiency was verified by comparing the results obtained by the alkaline extraction and by direct solid sample analysis using HR-CS GF AAS. The accuracy of the method for total Se determination was ascertained using microwave-assisted acid digestion as well as direct solid sample analysis by HR-CS GF AAS of the certified reference materials MURST-ISS-A1 (Antartic marine sediment) and BCR 142R (light sandy soil), and soil samples from different regions of Brazil.