A method for screening arsenolipids in fish oils by HPLC-ICPMS

We present a method for screening lipid-soluble arsenic compounds (arsenolipids) in fish oils by reversed-phase HPLC-ICPMS using a gradient elution with ethanol and acetate buffer at pH 6. Two different approaches were tested to reduce changes in arsenic response due to the carbon effect: addition of a supplementary methanol solution directly to the spray chamber or addition of methanol post-column through a T-piece. The latter method proved to be the best option for maintaining constant response for several arsenolipids covering a wide range of polarities. With the optimized method it is possible to perform a screening of at least three groups of arsenolipids with different polarities in 90 min with detection limits ranging from 5 to 11 mu g As L-1, depending on the analyzed compound. The method was applied to the screening of arsenolipids in fractions obtained from cod liver oil and capelin oil, which include arsenic-containing fatty acids, arsenic-containing hydrocarbons and another group of lower polarity and unknown character.