Method for speciation of organoarsenic in mussels by liquid chromatography coupled to electrospray ionization and QTRAP tandem mass spectrometry

Arsenic toxicity to humans critically depends on its chemical form. The Expert Committee of the FAO/WHO defined a tolerable intake only for inorganic arsenic although there are evidences on toxicity of some organoarsenic compounds. Arsenobetaine (AsB), arsenocholine (AsC), dimethylarsinic acid (DMA) and monomethylarsonic acid (MMA) are abundant species in shellfish. Herein, we present a fast and reliable method for speciation of organic arsenic in mussels by liquid chromatography coupled to electrospray tandem mass spectrometry on triple quadrupole (LC/ESI-MS/MS) with parallel determination of total arsenic by atomic absorption spectrophotometry (AAS) aimed at setting tolerable levels for both inorganic and organic arsenic in fishery products; methods performances were evaluated in terms of mean recoveries of the analytes, precision, specificity, limits of quantification (LOQs) and limits of detection (LODs). Finally, the described approach was employed to perform a survey about the contamination of organic arsenic in mussels from Campania region (Southern Italy).