Development of an Optimized Extraction Method to Recover Drug Material From Used Test Strips for Comprehensive Drug Checking

Drug-checking programs use point-of-need testing (e.g., test strips) and laboratory-based analysis to rapidly identify emerging drug threats, but each has limitations. Test strips are quick but compound or class specific, whereas laboratory testing can identify more compounds but have lengthy turnaround times. To address these limitations, it was proposed that compounds could be extracted from used test strips for additional analyses allowing for rapid on-site information followed by comprehensive laboratory results. The method development process involved four parts: determining the optimal extraction approach, assessing the feasibility of performing direct analysis in real-time mass spectrometry (DART-MS) analysis on extracts, determining the limits of detection (LODs) for a range of analytes, and evaluating the method using used test strips submitted by harm reduction sites. The optimized method consisted of extracting analytes of interest from a cut test strip using 0.5-mL methanol while vortexing for 10 s. DART-MS successfully identified the compounds of interests, and the test strip chemical background was identified. LODs were found to be as low as a mass fraction of 0.005 in a mixture. For the samples submitted by harm reduction sites, concordance between extracts and test strip results was 96%, and the agreement in compound identification between used test strip extracts and authentic drug collection samples was approximately 80% regardless of test strip type and preparation. This work shows that additional analyses of extracted test strips can provide a low-barrier way for high-quality testing that can be used to increase data on the drug landscape.