Extraction and detection of organoarsenic feed additives and common arsenic species in environmental matrices by HPLC–ICP-MS

Organoarsenic compounds, such as roxarsone (3-nitro-4-hydroxyphenylarsonic acid, ROX) and p-arsanilic acid (ASA), are widely used as animal feed additives, while animal wastes bearing these compounds are often used to fertilize agricultural land, which can cause arsenic pollution of soil, surface water, and groundwater. Determination of a number of inorganic and organic arsenic species in a variety of environmental matrices is necessary to study the environmental fate of organoarsenic feed additives and to assess their risk. A robust analytical method was developed in this work for precise and accurate quantification of ROX, ASA, dimethyl arsenic acid (DMA), monomethyl arsenic acid (MMA), arsenate [As(V)], and arsenite [As(III)] by HPLC–ICP-MS with gradient elution. Extraction conditions for recovering the inorganic and organic arsenic species from soils and sediments were also optimized, and the best results were obtained with 0.5 mol·L− 1 H3PO4 under constant shaking for 16 h. This method was applied in determining the levels of inorganic and organic arsenic species in sediments, soils, and surface water surrounding several swine farms in the Pearl River Delta in southern China and the results showed that the environmental media were already impacted by organoarsenic feed additives.