Quantitative Swab Touch Spray Mass Spectrometry for Oral Fluid Drug Testing

Simultaneous determination of 30 common drugs of abuse, including opioids, benzodiazepines, fentanyl derivatives, methamphetamines, cocaine, substituted methylenedioxyphenethylamines, cathinones, antidepressants, and antipsychotics, in neat oral fluid was carried out using touch spray mass spectrometry from volumetric absorptive microsampling swabs. A simple and rapid (<2 min per sample) method using multiple reaction monitoring was developed and fully validated, yielding satisfactory analytical performance. Minimal sample volumes (10 μL) were used, and neither sample transfer nor preparation steps were required. Most detection limits were below 5 ng/mL from the complex drug mixture in the biological matrix. Simulations of in vivo sampling were carried out and acceptable quantitative results were obtained even under these conditions, indicating the potential of this technique for fast and noninvasive point-of-care drug testing in clinical or forensic settings.