The recovery of illicit drugs from oral fluid sampling devices

Testing for drugs in oral fluid is a convenient procedure for determining recent drug use. A number of issues are still to be resolved and this paper investigates the effects of storage systems on drug stability and recovery using three different collection devices supplied by Cozart, Immunalysis and Microgenics (third party). Drugs were analysed using a range of immunoassay systems followed by MS confirmation and quantitation. The reproducibility of the weight of specimen collected was excellent (CV<10%) for the three collection devices tested. Of the three systems studied, only the Cozart product gave acceptable recovery of THC from drug-spiked oral fluid. A combination of Cozart, Immunalysis and Diagnostix immunoassays with the Cozart collection system gave the most sensitive and discriminating screening assays for the drugs studied, namely THC, benzodiazepines, methamphetamine and morphine. Storage at either 5 degrees C or room temperature had no significant effect on drug recoveries.