New Approaches to the Extraction of Arsenic Species from Soils

Arsenic extraction in natural and spiked soil samples was studied using two main types of extractants. The extractants were phosphoric acid used alone and with the addition of reducing agents (ascorbic acid and hydroxylammonium hydrochloride). The stability of arsenite (As(III)), arsenate (As(V)), monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA) in the extracts over time and under different storing conditions was assessed by means of LC-HG-AFS. A protocol was devised to extract arsenic species from soils. The protocol assures the stability of the original sample species in the extract proposed by using an extraction solution of phosphoric acid with ascorbic acid and by purging the extracts after microwave extraction. The total As, Mn and Fe content in aqua regia and in phosphoric extracts was also measured by ICP-AES in order to perform the mass balance.