The purpose of this study was to develop and validate a quantitative method for fentanyl analogs in oral fluid (collected via Quantisal™) using liquid chromatography-quadrupole-time-of-flight-mass spectrometry (LC-QTOF-MS).
Oral fluid is a valuable alternative matrix for forensic toxicologists due to ease of observed collection, limited biohazardous exposure, and indications of recent drug use. Limited information is available for fentanyl analog prevalence, interpretation, or analysis in oral fluid. With increasing numbers of fentanyl-related case of driving under the influence of a drug (DUID) cases appearing in the United States, the development of detection methods is critical. In the current study, validation resulted in limits of detection and quantification ranging from 0.5 to 1 ng/mL. Established linear range was 1–100 ng/mL for all analytes, except acetyl fentanyl at 0.5–100 ng/mL (R2 > 0.994). Within- and between-run precision and bias were considered acceptable with maximum values of ±15.2 percent CV and ±14.1 percent, respectively. Matrix effects exhibited ionization enhancement for all analytes with intensified enhancement at a low concentration (9.3–47.4 percent). No interferences or carryover was observed. Fentanyl analogs were stable in processed extracts stored in the autosampler (4⁰C) for 48 hours. The validated method was used to quantify fentanyl analogs in authentic oral fluid samples (n=17) from probationers/parolees. Fentanyl and 4-ANPP concentrations were 1.0–104.5 ng/mL and 1.2–5.7 ng/mL, respectively. (publisher abstract modified)