Assessment of a combined handheld Raman spectroscopy and transportable mass spectrometry approach for the analysis of seized drug mixtures

Abstract

Growing backlogs and lengthy turnaround times for seized drug analysis are causing significant strain on the judicial system. One potential solution is to improve field screening through on-site detection methods using field-portable instrumentation to reduce the amount of evidence submissions to forensic laboratories. However, incorporating field-portable instrumentation into routine on-site detection requires empirical data to establish each instrument's capabilities, limitations, and performance characteristics. This study evaluates using handheld Raman and transportable linear ion trap mass spectrometry instrumentation under controlled laboratory conditions to identify seized drug mixtures. A Rigaku ResQ-CQL handheld Raman spectrometer, a Field Forensics HandyRam™ handheld Raman spectrometer, and a BaySpec Continuity™ linear ion trap mass spectrometer were used to analyze seized drug mixtures. The analyzed mixtures contained cocaine or methamphetamine with levamisole, procaine, caffeine, and phenacetin at 1:1, 1:4, 1:10, and 1:20 ratios. The ability to identify controlled substances using the onboard library was evaluated for the ResQ-CQL and the Continuity™ instruments. Using the ResQ-CQL, only pure compounds and several of the 1:1 ratio mixtures had more than 85 % accuracy in identifying the controlled substance. In contrast, the Continuity™ demonstrated the ability to identify the controlled substance in the 1:4 and 1:10 ratio mixtures. When the data from the ResQ-CQL and the Continuity™ were considered together, an accuracy of at least 67 % was achieved for the 1:1, 1:4, and 1:10 mixtures. 100 % accuracy was achieved when the combined method was applied to identifying controlled substances in authentic destroyed casework samples.