Arsenic species extraction of biological marine samples (Periwinkles, Littorina littorea) from a highly contaminated site

Arsenic is ubiquitous in the tissues of marine organisms and in uncontaminated environments it is dominantly present as the highly soluble and easily extractable non-toxic arsenical, arsenobetaine. However in contaminated environments, higher proportions of inorganic arsenic, which is much less soluble, are accumulated into the tissues of marine organisms, resulting in lower extraction efficiencies (defined as the percent extracted arsenic of the total arsenic). This study carried out a comparative analysis between three different two-step arsenic extraction methods based on Foster et al. [27] from highly contaminated tissue of the marine periwinkle, Littorina littorea. The first extraction step used 100% water, 1:1 methanol–water, or a 9:1 methanol–water as the extraction solvent and the second step consisted of a gently heated dilute nitric acid extraction. The optimized two step extraction method was 1:1 methanol–water extraction followed by a 2% HNO3 extraction, based on maximum amounts of extracted species, including organoarsenic species.