Drug trash to treasure: quantitative mass spectrometric analysis of residual drugs from used lateral flow immunoassay test strips and syringe plungers

Abstract Introduction A major challenge to monitoring street drugs is the difficulty of obtaining samples of illegal substances for laboratory analysis. However, liquid chromatography-mass spectrometry (LC-MS/MS) can detect drug residues on legal materials, such as drug checking test strips, that contact drug substances. This study evaluates the feasibility of incorporating used test strips and used syringe plungers into routine laboratory drug checking. Methods Three factors that affect the recovery of 21 drugs from the test strips were assessed: the extraction solvent, test strip type, and analyte stability during storage. Seized drug samples were prepared quantitatively and applied to test strips, syringes, and syringe plungers to compare qualitative and quantitative recoveries. The applicability of the extraction methods was further assessed using authentic samples from Ohio and Massachusetts. Results The developed LC-MS/MS method successfully quantified most of the analytes to a concentration of 0.5 ng/mL, enabling the detection of clinically relevant amounts of drugs, including high-potency drugs like carfentanil and medetomidine. Methanol worked best to extract the drugs, the type of the strips did not impact recovery, and all 21 targeted drugs could be recovered with 12–87% extraction efficiency after four weeks of storage of the strips at room temperature. Conclusion Extracting drug residues from used test strips and syringe plungers was feasible and robust to solvent, brand, and storage challenges. Use of these samples reduces the burden of collecting unregulated solid drug samples, enhances staff safety, and provides a seamless integration of laboratory-based techniques into monitoring protocols.