Analysis of organophosphorus insecticides in biological samples by selective ion monitoring gas chromatography-mass spectrometry.

Gas chromatography with chemical ionization or electron impact mass spectrometry and selected ion monitoring provided a simple and sensitive method for measuring organophosphorus insecticides. Chemical ionization produced higher-mass ions which might increase the selectivity and sensitivity of the assay. The recovery of organophosphates from saline and urine was greater than 75%. The recovery of these compounds from plasma was less than the saline because of the binding of insecticides to plasma protein. Insecticides with lower LD50 values showed lower recovery from plasma than organophosphates with higher LD50 values.