Targeted screening with Library Searching of drugs of abuse by MTS measuring cocaine and related stimulants, amphetamines, opioids & benzodiazepines

Importance of the topic

In forensic and clinical toxicology, the growing diversity of illicit and prescribed drugs challenges conventional LC-MS/MS screening. Expanding target panels increases the risk of false positives and negatives while demanding robust quantitation and confident compound identification.

Objectives and study overview

• Develop a multi-targeted screening (MTS) assay for 90 drugs of abuse plus 32 deuterated internal standards in whole blood.
• Combine the sensitivity of multiple reaction monitoring (MRM) with library-searchable product ion spectra.
• Benchmark performance against a validated 2-MRM method on a Shimadzu LCMS-8050.

Methodology and instrumentation

• Sample preparation by QuEChERS: 100 µL whole blood extracted with acetonitrile, salt partitioning (MgSO₄/NaCl/NaOAc), centrifugation.
• UHPLC separation on a Raptor Biphenyl column (2.7 µm, 100×2.1 mm) at 40 °C; binary gradient of 2 mM ammonium formate/0.002% formic acid in water and methanol at 0.3 mL/min.
• Mass spectrometry on Shimadzu LCMS-8060: two MRM transitions per analyte; threshold of 10,000 counts triggers product ion scans at collision energies of 10, 35, and 55 V. The merged MS/MS spectrum is searched against an in-house library.

Instrumentation used

• Shimadzu LCMS-8060 triple quadrupole mass spectrometer
• Shimadzu Nexera UHPLC system
• Shimadzu LCMS-8050 triple quadrupole mass spectrometer (reference method)
• Raptor Biphenyl column (Restek)

Key results and discussion

• Library matching scores >70 and retention time deviations <0.1 min for most analytes at 100 µg/L, with calibration R² >0.99.
• Quantitative agreement between MTS and conventional 2-MRM methods (slope = 0.9996, R² >0.99 across 54 data points from 24 patient samples).
• High-confidence differentiation of isobaric compounds (e.g., morphine vs. hydromorphone) via merged spectra, reducing misidentification.

Benefits and practical applications

• Single, consolidated workflow for multiple drug classes (cocaine, stimulants, amphetamines, opioids, benzodiazepines).
• Streamlined sample preparation and chromatography reduce time and cost.
• Automated library searching in LabSolutions Insight supports rapid review-by-exception reporting.

Future trends and potential applications

• Expansion of spectral libraries to include new psychoactive substances and metabolites.
• Integration with high-resolution mass spectrometry for non-targeted screening.
• Extension to other biological matrices (urine, oral fluid) and expanded forensic or clinical contexts.

Conclusion

The MRM-triggered product ion scan approach on the LCMS-8060 provides robust quantitation equivalent to traditional MRM methods while delivering enhanced identification confidence through library matching. This versatile method addresses the complexity of broad drug panels and supports accurate screening in routine forensic and clinical toxicology.

References

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3. Dulaurent S, El Balkhi S, Poncelet L, Gaulier JM, Marquet P, Saint-Marcoux F. QuEChERS sample preparation prior to LC–MS/MS determination of opiates, amphetamines, and cocaine metabolites in whole blood. Analytical and Bioanalytical Chemistry. 2016;408(5):1467–1474.
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