Since 2011, toxicology labs across the United States have faced an ever-increasing caseload, with backlogs and analytical turn-around times that continue to grow despite efforts to increase sample throughput. Sample preparation is often the more time-consuming, labor-intensive, and error-prone portion of the analytical process. Biocompatible Solid Phase Microextraction (Bio-SPME) is a single-step sample preparation technique that is rapid, simple, and amenable to automation. Direct Analysis in Real Time (DART) is an ambient ionization technique that can be paired with mass spectrometry (MS) to rapidly detect, identify, and quantitate drugs of abuse in urine samples. When these methods are combined, the entire analytical process, from start to finish, can be completed manually in just over 2 minutes per sample. By increasing sample throughput and decreasing human labor, toxicology labs would benefit greatly by adopting such a rapid analytical technique.
This project focused on optimization of the Bio-SPME sample preparation process to maximize signal intensity and minimize preparation time per sample. 11-nor-9-carboxy-9-tetrahydrocannabinol (THC-COOH), benzoylecgonine, norfentanyl, and methamphetamine were selected as target analytes for detection and quantitation in specialty matrix urine (SMx urine). To prepare samples, octadecyl (C18) Bio-SPME fibers were subjected to a conditioning and extracting process prior to analysis via DART-MS. It was determined that a 15 minute conditioning period was sufficient to prepare the fibers for extraction. The extraction period was analyte-dependent with ideal analytes adsorbing to the fibers in as little as 15 minutes. Under ideal conditions, the entire sample preparation process was found to take as little as 30 minutes.
Multiple Reaction Monitoring (MRM) methods were built for each target analyte and their deuterated analog. For qualitative purposes, two to three transitions were included for each analyte, whereas the quantitative methods included only one transition per analyte. The limit of detection (LOD) for benzoylecgonine and methamphetamine was found to be 50ng/mL in urine. The LOD for norfentanyl was 75ng/mL in urine, and the LOD for THC-COOH was 250ng/mL in urine. Three of the four analytes were successfully quantitated using DART-MS when only a single analyte is present in the sample: benzoylecgonine and methamphetamine can be reliably quantitated between 50ng/mL and 1000ng/mL, while norfentanyl can be quantitated between 75ng/mL and 1000ng/mL. Data collected from the optimized sample preparation and targeted analytical process demonstrates that rapid detection, identification, and quantitation of metabolites from various drug classes are possible via DART-MS.
| Identifer | oai:union.ndltd.org:bu.edu/oai:open.bu.edu:2144/49466 |
| Date | 04 November 2024 |
| Creators | Knake-Wheelock, Kelsey |
| Contributors | Hall, Adam B. |
| Source Sets | Boston University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
| Rights | Attribution 4.0 International, http://creativecommons.org/licenses/by/4.0/ |
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