Using ambient mass spectrometry and LC-MS/MS for the rapid detection and identification of multiple illicit street drugs

Chien-Hua Chiang ^a, Hei-Hwa Lee ^b, Bai-Hsiun Chen ^b, Yi-Ching Lin ^b, Yu-Ying Chao ^c,**, Yeou-Lih Huang ^a,b,d,*

^a Department of Medical Laboratory Science and Biotechnology, College of Health Sciences, Kaohsiung Medical

University, Kaohsiung, Taiwan

^b Department of Laboratory Medicine, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan

^c Department of Public Health, College of Health Sciences, Kaohsiung Medical University, Kaohsiung, Taiwan

^d Department of Chemistry, National Sun Yat-sen University, Kaohsiung, Taiwan

In this study the recently developed technique of thermal desorption electrospray ionization/ mass spectrometry (TD-ESI/MS) was applied to the rapid analysis of multiple controlled substances. With the reallocation of mass spectral resources [from a standard ESI source coupled with liquid chromatography (LC) to an ambient TD-ESI source], this direct-analysis technique allows the identification of a wider range of illicit drugs through a dual-working mode (pretreatment-free qualitative screening/conventional quantitative confirmation). Through 60-MRM (multiple reaction monitoring) analysis-in which the MS/ MS process was programmed to sequentially scan 60 precursor ion/product ion transitions and, thereby, identify 30 compounds (two precursor/product ion transitions per compound) of a four-component (drug) standard, the signal intensity ratios of each drug transition were comparable with those obtained through 8-MRM analysis, demonstrating the selectivity of TD-ESI/MS for the detection of multiple drugs. The consecutive analyses of tablets containing different active components occurred with no cross-contamination or interference from sample to sample, demonstrating the reliability of the TD-ESI/MS technique for rapid sampling (two samples min^-1). The active ingredients in seized drug materials could be detected even when they represented less than 2 mg g^-1 of the total sample weight, demonstrating the sensitivity of TD-ESI/MS. Combining the ability to rapidly identify multiple drugs with the “plug-and-play” design of the interchangeable ion source, TD-ESI/MS has great potential for use as a pretreatment-free qualitative screening tool for laboratories currently using LC-MS/MS techniques to analyze illicit drugs.