Organophosphates (chlorpyrifos, diazinon, fenitrothion, fenthion, malathion)

The procedure described here permits the assay of the organophosphate insecticides chlorpyrifos, diazinon, fenitrothion, fenthion and malathion in whole blood. Exposure to these organophosphates that is of rlevance to occupational medicine can be determined. For this purpose whole blood stabilised with EDTA undergoes haemolysis in an ultrasonic bath. the organophosphates therein are enriched and purified on kieselguhr cartridges (Extrelut NT 20). After elution, the analytes are concentrated in a stream of nitrogen. On complention of separation by capillary gas chromatography, the samples are measured by means of a mass selective detector and electron impact ionisation (EI). Calibration curves for quantitative evaluation are plotted using calibration standards prepared with pooled human blood. The calibration standards are treated in the same manner as the whole blood samples to be investigated. Chlorpyrifos-diethyl-D10 is added to the blood samples as an internal standard. The detection limit of the method is between 0.5 and 2.6 ng per litre blood for the individual organophosphates.