Identification of arsenobetaine in sole,lemon sole,flounder, dab,carb and shrimps by field desorption and fast atom bombardment mass spectrometry

Organo-arsenic has been isolated from sole, lemon sole, flounder, dab, crab and shrimps by extraction or ion-exchange in combination with thin-layer chromatography. An alkaline digestion of the samples, followed by a reduction with sodiumborohydride leads to the formation of trimethylarsine. The behaviour of the organo-arsenic compound was very similar to that of synthesized arsenobetaine. Field desorption mass spectrometry (FDMS) can be used to identify arsenobetaine in the isolates. Sufficient purification by thin-layer chromatography is found to be a prerequisite for the detection of a protonated molecular ion of arsenobetaine. If this situation is not met acid enhanced FDMS or Fast Atom Bombardment mass spectrometry in high resolution can be used successfully.