Use of a new rapid bioluminescence method for screening organophosphate and N-Methylcarbamate insecticides in processed baby foods.
An enzyme with high specific affinity for organophosphate and N-methylcarbamate insecticides has been incorporated into a new test for detection of these insecticides at the level of parts per billion (ppb) (commercially available as the Charm Pesticide Test). To measure the extent of insecticide inhibition of the enzyme, a specific bioluminescent substrate is used. The signal is counterproportional to the amount of insecticides. Random sampling of four baby food brands and testing for the cumulative levels of organophosphate and N-methylcarbamate insecticides found carbaryl to be the most common residue. Out of the 155 samples tested there were 132 negative samples (85.2%) and 23 suspected positive samples (14.2%). The suspected positive samples were further analyzed by high-performance liquid chromatography (HPLC) and gas chromatography/mass spectrometry (GC/MS). Carbaryl was confirmed in 18 of the samples. One of the samples contained an active metabolite of tetrachlorvinphos and in 3 of the positive samples an insecticide could not be identified by GC/MS. One positive sample was not processed for confirmation due to high fat content.