Analysis of ecstasy in oral fluid by ion mobility spectrometry and infrared spectroscopy after liquid–liquid extraction

• IMS analysis of thermally desorbed MDMA in saliva using second derivative spectra.
• IMS and IR after LLME improves sensitivity and affords double confirmation.
• Detection limits in the parts-per-billion range.
• Potentially useful for on-site analyses.

We developed and evaluated two different strategies for determining abuse drugs based on (i) the analysis of saliva by ion mobility spectrometry (IMS) after thermal desorption and (ii) the joint use of IMS and infrared (IR) spectroscopy after liquid–liquid microextraction (LLME) to enable the sensitivity-enhanced detection and double confirmation of ecstasy (MDMA) abuse. Both strategies proved effective for the intended purpose. Analysing saliva by IMS after thermal desorption, which provides a limit of detection (LOD) of 160 μg L−1, requires adding 0.2 M acetic acid to the sample and using the truncated negative second derivative of the ion mobility spectrum. The joint use of IMS and IR spectroscopy after LLME provides an LOD of 11 μg L−1 with the former technique and 800 μg L−1 with the latter, in addition to a limit of confirmation (LOC) of 1.5 mg L−1. Using IMS after thermal desorption simplifies the operational procedure, and using it jointly with IR spectroscopy after LLME allows double confirmation of MDMA abuse with two techniques based on different principles (viz., IMS drift times and IR spectra). Also, it affords on-site analyses, albeit at a lower throughput.