Low-temperature plasma-probe mass spectrometry based method for determination of new psychoactive substances in oral fluid.

RATIONALE: Owing to the widespread abuse of new psychoactive substances (NPSs), developing a rapid, easily operable method to detect NPSs in oral fluid is of high priority. Their ease of collection and non-invasive nature make oral fluid samples suitable for on-site tests and forensic cases. Herein we report a rapid and sensitive method to screen and quantitate 11 new NPSs in oral fluid.

METHODS: Low-temperature plasma-probe mass spectrometry (LTP-MS) was applied and, to improve the signal intensity, thermally assisted desorption was employed. Tandem mass spectrometry was performed to exclude false positive signals and to decrease noise at the m/z values of interest.

RESULTS: Linearity was studied using matrix-matched calibration curves; all the analytes exhibited good linearity with R2 varying from 0.9907 to 0.9981. The estimated limits of detection (LODs) were in the range of 3.0-15.2 ng/mL, which are comparable to those of immunoassay; relative standard deviations (RSDs) are no greater than 23% at the studied concentration levels.

CONCLUSIONS: The proposed LTP-MS-based method was promising in forensic and on-site applications to curb the abuse of NPSs.