A rapid, cost-effective method for analyzing organophosphorus pesticide metabolites in human urine for counter-terrorism response

Organophosphorus (OP) pesticides are used as insecticides in agriculture and pest control and are often called "junior strength" nerve agents because they share the same mechanism of toxicity. OP pesticides are metabolized to dialkylphosphates and other metabolites, which are excreted in urine. In case of a terrorism incident involving widely available OP pesticides, an occurrence that may be likely given their widespread availability, a rapid, accurate, and cost-effective method for detecting exposure is required.We have evaluated several analytical methods to determine the most reliable and cost-effective methods for incident response. Our comparisons have included different internal standards (isotopically labeled standards versus chemically similar surrogate standards), different isolation techniques (some of which are automatable), and different analysis platforms. We found that isotopically labeled standards were a necessity to provide accurate quantification; the chemically similar surrogate was not suitable as an internal standard. The most sensitive and precise method uses isotopically labeled standards with gas chromatography-tandem mass spectrometry analysis. However, the most cost-effective method employed isotopically labeled standards with gas chromatography-single quadrupole-mass spectrometry using a less expensive mass selective detector. Because this method is lower in cost, it may be a more viable option for equipping multiple laboratories with chemical-terrorism response capabilities.