Novel sample preparation methods and field testing procedures used to determine the chemical basis of cocaine detection by canines

The use of canines to signal money associated with drug trafficking is a major point of contention among dog handlers, forensic scientists, and the legal community particularly in light of recent reports that a significant amount of money in circulation is contaminated with detectable amounts of cocaine. The questions raised include: What exactly are the dog alerting to? How selective are the dogs? How sensitive are the dogs? How reliable are the dogs? Tests with various volatile cocaine by-products confirm that the dominant chemical in cocaine odor is methyl benzoate. Field tests on fifteen different drug detector dogs with varying breeds, ages and training regimes show a consistent threshold level of 1 mu g Of methyl benzoate spiked along with cocaine on US currency required to initiate an alert. The majority of the canines did not alert to pharmaceutical grade cocaine even at levels as high as 1 g. Methyl benzoate is shown to evaporate rapidly from individual bills and is a function of the available surface area for wrapped currency. The canines tested were remarkably selective and reliable even under varying test conditions and using different delivery devices.