Rapid Extraction and Qualitative Screening of 30 Drugs in Oral Fluid at Concentrations Recommended for the Investigation of DUID Cases

A rapid, simple extraction method followed by qualitative screening using liquid chromatography–tandem mass spectrometry (LC–MS-MS) for drugs in oral fluid is presented. The decision points were selected to be at, or lower, than those recommended as Tier I compounds by the National Safety Council’s Alcohol, Drugs and Impairment Division for toxicological investigation of driving under the influence of drug (DUID) cases and were also at, or lower, than those recommended by Substance Abuse and Mental Health Service Administration and the Department of Transportation for Federal workplace drug testing programs. The method included 30 drugs: delta-9-tetrahydrocannabinol, amphetamine, methamphetamine, 3,4-methylenedioxymethamphetamine, 3,4-methylenedioxyamphetamine, cocaine, benzoylecgonine, carisoprodol, meprobamate, zolpidem, alprazolam, clonazepam, 7-aminoclonazepam, diazepam, nordiazepam, lorazepam, oxazepam, temazepam, codeine, morphine, 6-acetylmorphine, buprenorphine, fentanyl, hydrocodone, hydromorphone, oxycodone, oxymorphone, methadone, tramadol and phencyclidine. Phencyclidine was included because it is in the Federal workplace program even though it is considered a Tier II drug for DUID cases. A liquid−liquid extraction method using isopropanol, hexane and ethyl acetate to extract drugs from the oral fluid−buffer mix collected in a Quantisal™ device, followed by LC–MS-MS screening, was developed and validated according to ANSI/ASB 2019 Standard Practices for Method Validation in Forensic Toxicology. Interference studies, limit of detection, precision at the decision point, ionization suppression/enhancement and processed sample stability were determined for each drug. The method was successfully applied to proficiency specimens and routine samples received in the laboratory.