Detection of phytocannabinoids from buccal swabs by headspace solid phase microextraction – gas chromatography/mass spectrometry
Headspace solid phase microextraction (HS-SPME), which is a solvent-free extraction technique, was configured with gas chromatography/mass spectrometry (GC/MS) to detect phytocannabinoids from buccal swabs. The HS-SPME extraction procedure, i.e. extraction time, extraction temperature, thermal desorption parameters as well as headspace derivatization, were evaluated to extract major phytocannabinoids from the headspace of air-dried buccal swab samples. Sub micrograms of Δ9-tetrahydrocannabinol (THC) and cannabidiol (CBD) spiked onto buccal swabs could be extracted and detected by the HS-SPME-GC/MS approach. The analytical system can be readily automated without the use of solvent extraction. No interference peaks for phytocannabinoids were found in the total ion chromatograms obtained from the tested buccal swabs using cotton as the substrate. Interference background can also be minimized by using selected ion monitoring. This analytical approach potentially could be adopted to detect marijuana smokers by the identification of residual phytocannabinoids from oral cavities for forensic applications.