Matrix Solid-Phase Dispersion as a Sample Pretreatment for the Speciation of Arsenic in Seafood Products

Matrix solid-phase dispersion (MSPD) has been applied to extract arsenical species (arsenite, As(III); arsenate, As(V); monomethylarsonic acid; dimethylarsinic acid, DMA; arsenobetaine, AsB; and arsenocholine) from seafood products. High-performance liquid chromatography coupled to inductively coupled plasma-mass spectrometry was used to separate and detect all arsenic species. Variables affecting MSPD, such as the solid support material (dispersing agent), solid support mass/sample mass ratio, elution solvent composition, and elution solvent volume, have been fully evaluated. Quantitative recoveries for inorganic and organic arsenic species have been obtained when using diatomaceous earth or octadecyl-functionalized silica gel (C18) as a solid support material, with a solid support mass/sample mass ratio of 7.0. Elution of arsenical compounds has been assessed using 10 mL of 50/50 methanol/ultrapure water as an elution solvent. The MSPD method has been found precise, with RSDs of ∼9% for As(III), DMA, and As(V) and 3% for AsB. The developed procedure has been tested by analyzing different certified reference materials of marine origin such as DORM-2 and BCR 627, which offer certified contents for some arsenic species. The method has been also applied to assess arsenic speciation in different mollusks, cold water fishes, and white fishes.