MSACL 2018 US Abstract

Topic: Cannabinoids

Screening for Synthetic Cannabinoids in Blood Using LC-QTRAP

Matthew McMullin (Presenter)
NMS Labs

Bio: Mr. McMullin is a Toxicologist at NMS Labs and is responsible for authoring forensic toxicology report in post mortem and human performance cases and providing support court testimony. He is a Fellow of the American Board of Forensic Toxicology and certified by the National Registry in Clinical Chemistry as a Toxicological Chemist. Mr. McMullin earned a Masters of Chemistry Degree from St. Joseph's University and is a graduate of DeSales University.

Authorship: Matthew McMullin, Stephanie Kumor and Joseph Homan
NMS Labs, 3701 Welsh Road, Willow Grove, PA, USA

Short Abstract

Since 2009 when we first encountered synthetic cannabinoids in blood the structural diversity has created analytical challenges with variable and for some poor ionization efficiencies. The enhanced sensitivity and specificity of the 2-dimensional QTRAP has made it possible to detect 36 analytes in a single method; and we can easily update the scope of analysis without major changes to the basic analytical method. The results from testing of 1241 blood samples in 2017 shows that 5-ADB, FUB-AMB and ADB-FUBINACA are currently the three most prevalent drugs in this case.

Long Abstract

Introduction

New and legal synthetic cannabinoids continue to appear in the illicit market as regulators schedule older synthetic cannabinoids. Testing for synthetic cannabinoids in human biological samples following use requires a variety of analytical tools. Blood is the most commonly tested matrix in our laboratory since findings can better be interpreted in post mortem and driving under the influence cases. We have chosen to use a 2-dimensional LC-QTRAP approach for screening followed by two separate LC-MS/MS confirmation procedures. The QTRAP’s sensitivity, specificity, ability to quickly update and ease of use make it a viable candidate for this application.

Methods

The scope of these analyses needs to be updated on regular bases meaning redevelopment and validation of the screen and confirmation methods. The current method screens for 36 targets using 5 internal standards. The lack of labeled internal standard for most analytes adds to the analytical challenges.

In summary, following the addition of isotopically labeled internal standards, 0.5 mL aliquots of samples are buffered to pH 10.2 and extracted with 3 mL of methyl t-butyl ether. The solvent is separated and evaporated to dryness and reconstituted with 50:50 deionized water:methanol containing 0.1% formic acid. Analyses were performed using a Shimadzu Prominence HPLC with a two-dimensional trap on a C6-Phenyl guard column and the 2nd dimension on a C18 analytical column with a gradient elution. An AB SCIEX 4500 QTRAP was used with a single point calibration for qualitative detection. Data analysis was with Multi-Quant and Library View. A positive result must have a response of >50% of the cut-off calibrator and a library match >60%. Positive screens are confirmed using a fresh aliquot and a different LC-MS/MS method. This screening method was validated by determining precision around the cut-off, sensitivity, specificity, interfering substances, matrix effects, stability and carryover. All acceptance criteria met laboratory SOPs and SWGTOX guidelines.

Extractions from samples are re-injected off-line using an exploratory method to test for potentially abused new synthetic cannabinoids. This guides in adding new analytes to the next planned update of the method.

Results

This method with its updated scope went into use in January 2017, and through September 2017 we have tested 1241 blood samples with 24.6% of the cases testing positive for at least one analyte. Listed below are the positivity rates of the most commonly encountered analytes. Also in the table are the DEA’s most recent prevalence ranking from its mid-2017 report for comparison (1).

Drug NMS Positivity DEA Prevalence

5F-ADB 10.4% 2nd

FUB-AMB 6.9% 1st

ADB-FUBINACA 4.7% 3rd

AB-FUBINACA 1.8% 5th

ADB-CHMINACA 1.3% 6th

Conclusions & Discussion

Since 2009 when we first encountered synthetic cannabinoids the structural diversity has created analytical challenges with variable and for some poor ionization efficiencies. This LC-QTRAP method has proven to be a good analytical tool for the analysis of synthetic cannabinoids in blood because of its selectivity (fragmentation patterns for spectral comparison), sensitivity (accumulation of fragments for enriched response) and rapid data processing. It also allows easier updates to the method as new candidates are added to the scope of testing without disruption of the basic analytical parameters.

Reanalysis of extracted samples yields information on what new analytes to target in our next scope update. To date we have identified 4-cyano CUMYL BUTINACA and 5F-MDMB-PICA as candidates for addition.

A comparison of our findings to the most recent DEA Emerging Threat Report for the mid-year 2017 show a very similar mix and prevalence.


References & Acknowledgements:

1. Emerging Threat Report - Mid-year 2017 - DEA Special Testing and Research Laboratory


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