Method Validation of a Comprehensive Drug Screen Using Supported Liquid Extraction and LC/QTOF-MS - ARCHIVAL



This event originally occurred on January 19th, 2022 from 1pm – 2:30pm (EST). All presentations and material have been archived for you to access as On-Demand content.

Sponsored by Agilent Technologies

Immunoassays (IA) have offered sufficient sensitivity in toxicology for many decades. However, it lacks specificity and introduces technical challenges associated with identifying a growing number of new psychoactive substances (NPS). In contrast, mass spectrometry (MS)-based techniques can be used to simultaneously identify a broader scope of compounds with multiple data acquisition modes and retrospective data analysis. Many complex biological matrices are encountered in these investigations, although blood is the most encountered biofluid. The extraction of multiple drugs with different physicochemical properties using a single protocol can be challenging. As such, many MS-based screening methods do not include cannabinoids, and laboratories still rely on IA-based detection.

In this webinar, method validation of a SLE LC/QTOF-MS method is presented that simultaneously isolates >200 drugs, including 11-nor-9-carboxytetrahydrocannabinol (THCA), from whole blood at the recommended cutoff concentrations for DUI investigations. Limits of detection (LOD) for Tier I drugs ranged from 0.5 to 50 ng/mL. All compounds (including challenging analytes, e.g. THCA) were detected at or below the recommended cutoffs. Matrix effects and detectability for all analytes at their specified cutoffs were established using 10 independently sourced samples. Ion suppression and enhancement were observed. Retention time, mass accuracy, and coelution scores were used for identification purposes.

Extraction efficiencies were highly compound dependent, and the SLE protocol was selectively optimized to increase THCA recovery at the expense of other compounds that were more readily detected. The lowest extraction efficiencies using the SLE approach were observed for zwitterions (e.g. benzoylecgonine). Carryover, processed sample stability and interferences were also evaluated, and a total of 10 isotopically labeled internal standards were utilized. The scope and sensitivity of testing met or exceeded current recommendations for impaired driving investigations and included relevant medicolegal death investigations compounds of interest.

Detailed Learning Objectives:

• Learn the advantages of utilizing mass spectrometry-based drug screening

• Learn supported liquid extraction, an emerging technique in forensic toxicology

• Understand the challenges involved with comprehensive extraction procedures



For Forensic Use

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