Quantitation of an oral fluid drug panel including THC using High Resolution Accurate-Mass (HRAM) orbitrap mass spectrometry

Abstract

Aim

To develop a HRAM LCMS method for quantitative analysis of 31 drugs of abuse in oral fluid with a complete sample preparation workflow that satisfies cutoff levels presented by the National Safety Council. The 31 analytes are as follows:

6-MAM, 7-aminoclonazepam, Alprazolam, Amphetamine, Benzoylecgonine, Buprenorphine, Carisoprodol, Clonazepam, Cocaethylene, Cocaine, Codeine, Diazepam, Fentanyl, Hydrocodone, Hydromorphone, Lorazepam, MDA, MDMA, Meprobamate, Methadone, Methamphetamine, Morphine, Nordiazepam, Oxazepam, Oxycodone, Oxymorphone, PCP, Temazepam, THC, Tramadol, and Zolpidem.

Method

Nine calibration levels (ranging from 0.5 to 1000 ng/mL) were made by spiking stock solution of the 31 target analytes into human oral fluid. Samples were diluted with a preserving buffer and spiked with their corresponding internal standard. 500 μL of each sample were then extracted using DPX INTip™ SCX/WAX SPE. Drug analytes were separated with on a Thermo Scientific™ Accucore™ Biphenyl column connected to a Thermo Scientific™ Vanquish™ Horizon UHPLC system using a fast 7-minute method. Data was acquired on the Thermo Scientific™ Orbitrap™ Exploris™ 120 mass spectrometer using data dependent MS2 mode (ddMS2) with an inclusion list for the 31 target drugs. Thermo Scientific™ TraceFinder™ 5.2 software was used for data acquisition and processing.

Results

Limits of quantitation (LOQ) determined for the 31 drugs were all below the new SAMHSA guidelines cutoffs and linearity was achieved from as low as 0.5 ng/mL to a ULOL of 1,000 ng/mL. THC delta-9 achieved an LOQ of 1 ng/mL. All drugs were confirmed with mass accuracy of less than 5 ppm, retention times, and library matching. This study was also able to overcome some of the issues commonly associated with THC including “stickiness” of the drug to consumables and its susceptibility to being suppressed by oral fluid collection device buffers.

Conclusion

This fast and quantitative method was developed around 31 drugs of abuse specified by SAMHSA and the National Safety Council. A complete workflow was presented that involved sample preparation using DPX INTip SPE. Linearity was achieved from LOQ's as low as 0.5 ng/mL up to 1000 ng/mL which exemplifies the sensitivity of these instruments and extraction procedure. This fast and sensitive method for oral fluid testing sufficiently passes the SAMHSA guidelines.