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

Importance of the topic

A broad, reliable screening method for drugs of abuse is essential in clinical toxicology and forensic laboratories to address the growing use of both illicit and legalised substances. High confidence in compound identification and accurate quantitation reduce false positive and false negative reporting, improving patient safety, legal outcomes and quality control.

Study objectives and overview

This work describes the development and evaluation of a multi-targeted screening (MTS) assay capable of measuring 90 drugs of abuse plus 32 deuterated internal standards in whole blood. The study compared the new MTS approach on a Shimadzu LCMS-8060 platform with a validated 2-MRM method on an LCMS-8050, assessing identification confidence, quantitation accuracy and workflow efficiency.

Methodology and instrumentation

The sample preparation used a generic QuEChERS protocol: 100 µL whole blood was extracted with acetonitrile containing internal standards, partitioned with MgSO4/NaCl/NaOAc salts, centrifuged and diluted in mobile phase. Chromatographic separation employed a Nexera UHPLC system with a Raptor Biphenyl column (100 × 2.1 mm, 2.7 µm) at 40 °C, flow 0.3 mL/min, and a binary gradient of 2 mmol/L ammonium formate with 0.002 % formic acid in water (A) and methanol (B). Mass spectrometry used ESI+/- on the Shimadzu LCMS-8060, acquiring two MRMs per compound plus threshold-triggered product ion scans at collision energies of 10, 35 and 55 V. The three MS/MS spectra were merged into a single library-searchable spectrum. Data processing utilised LabSolutions Insight for review-by-exception.

Main results and discussion

The MTS method achieved similarity scores above 70 for 90 targets; calibration linearity (5–2000 µg/L for benzodiazepines, 5–500 µg/L for stimulants and opioids) yielded R²>0.99 and accuracy within ±12 %. Isobaric compounds such as morphine and hydromorphone were confidently distinguished by library matching. Analysis of 24 patient samples across four panels produced 54 data points; regression between MTS and conventional 2-MRM quantitation gave slope=0.9996 and r²>0.99, demonstrating equivalent quantitative performance.

Benefits and practical applications

• Single extraction and chromatographic method for multiple drug classes reduces assay complexity.
• Merged MS/MS library searching enhances specificity and reduces false reporting.
• Quantitative data quality matches conventional targeted MRM workflows.
• Flexible data review with LabSolutions Insight accelerates reporting.

Future trends and opportunities

The integration of high-resolution mass spectrometry and expanded spectral libraries will further improve screening scope and identification confidence. Automating spectral matching and retention time prediction with machine learning could accelerate method development. Adaptation of this workflow to other biological matrices (urine, saliva) and incorporation of novel psychoactive substances will broaden its forensic and clinical utility.

Conclusion

This MTS approach combining QuEChERS sample preparation, single-run UHPLC separation and triggered product ion MS/MS on an LCMS-8060 delivers robust, high-confidence screening and quantitation for a wide range of drugs of abuse. It matches conventional MRM methods in quantitation while offering superior identification specificity, making it a valuable tool for routine clinical toxicology and forensic analysis.

References

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