Arsenic speciation in fish sauce samples determined by HPLC coupled to inductively coupled plasma mass spectrometry

Fish sauce is a condiment typically used in most East Asian cooking and has recently been considered as an effective route to iron fortification in countries where iron deficiency anaemia is widespread. Current consumption and the increasing awareness of the uniqueness of fish sauce as a condiment necessitate assessment of the health risk that it poses. This study focuses on the analysis of arsenic in fish sauce samples with special emphasis on identification of the species present as a consequence of the fermentation process. Total arsenic concentrations of six different fish sauces from Thailand and Vietnam were in the range of 0.69–2.75 mg l−1. Speciation analyses done on the fish sauce samples showed that most of the arsenic present in the fish sauces were arsenobetaine (82–94%), arsenocholine (4.9–7.7%), trimethylarsine oxide (0.7–7.8%), and trimethylarsenopropionate (0.5–2.1%). Highly toxic arsenic compounds, such as arsenite, arsenate, methylarsonic acid (MA) and dimethylarsinic acid (DMA), were below the detection limit of 0.01 mg l−1.