Detection of marihuana use by GC/MS analysis of mouth swabs

A relatively simple and rapid test for detection of the components of Cannabis sativa (marihuana) after smoking consists of swabbing the exposed areas with an alcohol-containing swab, then concentrating the extract from the swab for direct analysis by Gas Chromatography-Mass Spectrometry. This test is now performed in several medical examiner's offices. This study was performed to evaluate this test using volunteer marihuana-smoking subjects. Caution must be used in interpreting the results obtained because of the transient nature of the intoxication, and because of the possibility of obtaining false-positive results. The time response and other parameters concerning the procedure are also discussed.