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Quantitation of drugs of abuse in body fluids is challenging due to the varying concentrations and substantially different chemical and physical properties of the drugs, interfering matrices, occasionally small volumes of sample to test, and the presence of many similar compounds. Further, constant evolution of drugs makes it harder to identify and quantitate them. Currently, most of the quantitative analysis is done using a selected reaction monitoring (SRM) approach on a triple-stage quadrupole mass spectrometer. This approach is inherently targeted and misses new compounds. Also, the SRM duty cycle limits monitoring, and quantitating large numbers of analytes is very difficult if not impossible. For the first time, high-resolution, accurate mass spectrometry based on Orbitrap™ technology offers a practical solution for the challenge at hand. The high resolution of up to 140,000 FWHM enables separation of drugs and metabolites from interferences. Fast positive/negative switching catches acidic, basic and neutral drugs. Better than 3 ppm mass accuracy assures confidence in identification, and fragment ions from the HCD cell further confirm the identity beyond a reasonable doubt. All of this is made simple by using Thermo Scientific TraceFinder and ExactFinder software, which help attain high productivity and confidence in routine targeted and general unknown screening applications.
Here we describe the application of Orbitrap technology-based workflow solutions for quantitation of drugs and metabolites in urine, plasma, whole blood, and oral fluid matrices.

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Workflow Overview for the NIDA-5 Panel

The most commonly used screening category for drugs of abuse is called the NIDA-5 (National Institute on Drug Abuse), which includes opiates, amphetamines, cocaine and metabolites. Quantitation of this panel of drugs of abuse in urine is performed in many forensic toxicology labs. The Substance Abuse & Mental Health Services Administration (SAMHSA) guidelines specify the concentration cut-offs and dynamic range needs for this analysis. The analytical workflow must be capable of handling highly polar isobaric/isomeric molecules, matrix interferences, wide dynamic ranges, ion suppression and significant sample-to-sample differences caused by the varying nature of the urine matrix. The quantitative analysis of this panel traditionally done by GC-MS is now beginning to be done by LC-MS/MS. High-resolution MS offers an easier and faster alternative to SRM assays using LC-triple quadrupole systems.
The workflow described is a new methodology in which all the analytes are monitored using one sample preparation procedure and a single LC-MS run. It involves enzymatic hydrolysis followed by methanol dilution for sample preparation. It uses full-scan MS at 70,000 to 100,000 FHWM resolution. The LC-MS analysis quantifies the following panel of compounds: amphetamines, methamphetamine, MDA, MDMA, MDEA, BE, THCA, PCP, Morphine, Codeine, and 6MAM. The methodology presented here meets all SAMHSA method validation guidelines.




Analysis of Expanded NIDA 5 panel Using Exactive System

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