Data-independent screening method for 14 fentanyl analogs in whole blood and oral fluid using LC-QTOF-MS

Abstract

Recently, fentanyl analogs account for significant number of opioid deaths in the United States. Routine forensic analyses are often unable to detect and differentiate these analogs due to low concentrations and presence of structural isomers. A data-independent screening method for 14 fentanyl analogs in whole blood and oral fluid was developed and validated using liquid chromatography-quadrupole-time-of-flight mass spectrometry (LC-QTOF-MS). Data were acquired using Time of Flight (TOF) and All Ions Fragmentation (AIF) modes. The limits of detection (LOD) in blood were 0.1–1.0 ng/mL and 0.1–1.0 ng/mL in TOF and AIF modes, respectively. In oral fluid, the LODs were 0.25 ng/mL and 0.25–2.5 ng/mL in TOF and AIF modes, respectively. Matrix effects in blood were acceptable for most analytes (1–14.4%), while the nor-metabolites exhibited ion suppression >25%. Matrix effects in oral fluid were −11.7 to 13.3%. Stability was assessed after 24 h in the autosampler (4 °C) and refrigerator (4 °C). Processed blood and oral fluid samples were considered stable with −14.6 to 4.6% and −10.1 to 2.3% bias, respectively. For refrigerated stability, bias was −23.3 to 8.2% (blood) and −20.1 to 20.0% (oral fluid). Remifentanil exhibited >20% loss in both matrices. For proof of applicability, postmortem blood (n = 30) and oral fluid samples (n = 20) were analyzed. As a result, six fentanyl analogs were detected in the blood samples with furanyl fentanyl and 4-ANPP being the most prevalent. No fentanyl analogs were detected in the oral fluid samples. This study presents a validated screening technique for fentanyl analogs in whole blood and oral fluid using LC-QTOF-MS with low limits of detection.