Extraction of aldicarb and its metabolites from excreta and gastrointestinal tissue

Carbamate insecticide screens often include aldicarb and its oxidative metabolites, aldicarb sulfoxide (ASX), and aldicarb sulfone (ASN). The rapid hydrolysis and thermal cleavage of the C-N bond within the carbamate functional group of these compounds produces nitrile transformation products. Nitriles are primary transformation products from aldicarb, its sulfoxide, or its sulfone. However, these nitriles are infrequently monitored. The method reported used acetonitrile/water extraction and HPLC postcolumn derivitization to determine aldicarb, ASX, and ASN from avian excreta and from gastrointestinal (GI) tissue. Recoveries of aldicarb, ASX and ASN from excreta were of 79% +/- 5.4, 120% +/- 7.7, and 93% +/- 6.2, respectively. Recoveries from tissue were 70% +/- 5.0, 80% +/- 12.1, and 85% +/- 6.7, respectively. The same extraction procedure and a GC-FPD analysis were used to determine nitrile metabolites from the same tissues. Aldicarb nitrile, ASX nitrile, and ASN nitrile recoveries from excreta were 42% +/- 2.3, 65% +/- 3.6, and 79% +/- 3.3, respectively. Overall recoveries from tissue were 29% +/- 3.4, 72% +/- 8.3, and 83% +/- 11.4, respectively. Since aldicarb, ASX, and ASN are normally detectable in organ tissues for 1-2 days following exposure, determining the presence of nitrile cleavage products provides an important forensic tool for evaluating aldicarb exposures.