Arsenic speciation in canned tuna fish samples (Thunnus) using ionic chromatography inductively coupled plasma mass spectrometry

Arsenic speciation analysis was conducted on in oil and in brine canned solid tuna samples using ionic chromatography inductively coupled plasma mass spectrometry (IC-ICP-MS). First, the method was optimized and validated. The extraction of water-soluble arsenic species (arsenobetaine (AsB), dimethylarsinic acid (DMA), monomethylarsonic acid (MMA), As (III), and As (V)) was performed with (NH4)2CO3 at pH 10.5. The presence of the sample matrix showed no effect on the selectivity of the method by a t-test (p < 0.05) and an external calibration method was applied. The limits of quantification for the five arsenic species were 0.59 mg kg−1 (AsB), 0.10 mg kg−1 (DMA), 0.12 mg kg−1 (As (III)), 0.07 mg kg−1 (MMA) and 0.10 mg kg−1 (As (V)). Method accuracy was tested through the analysis of the reference material BCR-627 (tuna fish muscle tissue) and a good agreement was obtained. Total arsenic in the solid canned tuna ranged from 2.65 to 5.81 mg kg−1 in-oil samples and from 2.74 to 5.70 mg kg−1 in the in-brine samples, levels higher than the limits established by the Brazilian sanitary standards. However, the speciation showed that the major species is the non-toxic arsenobetaine.