Speciation of Arsenic in the Atmosphere

In this paper is presented a study of speciation of arsenic in air, consisting in the separation and determination of arsine, metallic arsenic, inorganic trivalent and pentavalent arsenic, organic monomethylarsonic acid (MMA), dimethylarsinic acid (DMA) and/or their salts. These arsenic compounds are the most common found in air and are characterised by different toxicities. The proposed procedure is based on a sequential sampling where, first, the air is filtered on a cellulose membrane to collect the particulate matter, then it is purged into proper solutions able to stop the arsenic species present in the vapour state, except arsine. This latter compound is retained in an oxidising solution of permanganate as arsenate. The determination of the different species of arsenic in the particulate and in the vapour phase is described as well the typical interferences that can be encountered either in the solubilization procedure or in the analytical measurements: in many cases suggestions are proposed in order to minimise them.