Quantitative clinical toxicological screening comparing Library ID from product ion scan MS/MS to MRM Spectrum mode ID

Significance of the Topic

Clinical and forensic toxicological screening demands both sensitive quantitation and reliable compound identification. False positives and negatives can carry serious legal and medical repercussions, so maximizing specificity and confidence in routine analyses is crucial. High‐throughput methods that integrate robust quantitation with library‐driven confirmation address these needs.

Study Objectives and Overview

This work compares three MS/MS acquisition approaches for blood‐based toxicology panels containing benzodiazepines and cocaine‐antipsychotic‐opioid (CAO) compounds. The aim is to evaluate quantitative performance and identification confidence when using conventional 2-MRM methods, MRM‐triggered product ion scans, and a novel MRM Spectrum mode.

Methodology and Instrumentation

The study used whole blood spiked with 35 benzodiazepines or 44 CAO analytes. Sample cleanup employed a QuEChERS protocol with isotopic internal standards. Chromatography was performed on a Nexera UHPLC with a Restek Raptor Biphenyl column (100×2.1 mm, 2.7 µm) at 50 °C, 5 µL injection, 0.3 mL/min flow, and a water/methanol gradient containing ammonium formate and formic acid. MS/MS data were acquired on a Shimadzu LCMS-8060 with heated ESI, rapid polarity switching, 15 000 u/sec scan speed, and optimized MRM dwell times. A spectral library of over 1200 compounds, each characterized by multiple collision energies and retention times, supported library matching.

Main Results and Discussion

All three acquisition modes produced equivalent quantitative figures of merit (R2>0.99, accuracy 85–115%, precision <10% RSD) across calibration ranges of 5–500 µg/L. For benzoylecgonine, calibration slopes and intercepts were nearly identical among methods. Both MRM Spectrum and triggered product ion scans yielded rich fragmentation profiles that matched library spectra with high similarity scores (>95), whereas conventional 2-MRM lacked spectral confirmation. In patient sample tests, measured concentrations agreed within 5%, while library match scores improved compound confirmation even at low or high concentration extremes.

Benefits and Practical Applications

• Enhanced specificity through multiple fragment transitions.
• Library‐based confirmation reduces false reporting.
• Maintains quantitative sensitivity and linearity.
• Streamlines workflow for clinical and forensic labs.

Future Trends and Potential Applications

• Expansion of spectral libraries to cover new drug classes.
• Integration with automated data review and AI‐based anomaly detection.
• Real‐time monitoring using high‐density MRM data streams.
• Application in emergency toxicology and workplace testing.

Conclusion

MRM Spectrum mode and MRM‐triggered product ion scanning both achieve quantitative performance on par with conventional methods while providing library‐searchable spectra for improved identification confidence. These approaches offer versatile, high‐throughput solutions for routine clinical and forensic toxicology screening.

References

• Barnes A, Robin T, Dulaurent S, Elbalkhi S, Loftus N, Marquet P, Saint-Marcoux F. Quantitative clinical toxicological screening comparing Library ID from product ion scan MS/MS to MRM Spectrum mode ID. ASMS 2017, MP-721.