This article reports on the successful air sampling and detection of cocaine, methylenedioxymethylamphetamine (MDMA), and marijuana, using SPME-IMS achieved by targeting their volatile markers (methyl benzoate, piperonal, and terpenes, respectively).
Conventional methods of direct air sampling for drugs are ineffective because the parent compounds of these drugs have very low vapor pressures, making them unavailable for headspace sampling. Instead of targeting the parent drugs, IMS was set at the optimal operating conditions (determined in previous work) in order to detect their volatile chemical markers. SPME is an effective and rapid air sampling technique for the preconcentration of analytes which is especially useful in confined spaces such as cargo containers, where the volatile marker compounds of drugs can be found in sufficient concentrations. By sampling the air using a 100 μm polydimethyl siloxane (PDMS) SPME fiber for as little as one minute, enough mass of the targeted volatile markers in the headspace of a quart-sized metal paint can (gallon, ∼1101 cm3) which contained sub-gram quantities of the drug samples was recovered for IMS detection. Additionally, several potentially interfering compounds found in goods commonly shipped in cargo containers were tested individually as well as in mixtures with the drugs. No peak interferences were observed for MDMA or marijuana, and minimal peak interferences were found for cocaine. 25 references (publisher abstract modified)