A Forensic Triple Quadrupole GC/MS MRM Database for Forensic and Toxicological Workflows

Significance of the Topic

The continuous emergence of novel toxicants, low analyte concentrations, and complex matrices pose significant challenges in forensic toxicology. Gas chromatography coupled with triple quadrupole mass spectrometry operated in multiple reaction monitoring mode offers enhanced sensitivity, selectivity, and reproducibility compared to full scan GC/MS, making it a powerful tool for targeted screening and quantitation in forensic and toxicological workflows.

Objectives and Study Overview

This work aimed to develop a comprehensive database of MRM transitions for GC-amenable toxicologically relevant compounds. The curated library comprises 176 entries encompassing 154 unique analytes, including underivatized, trimethylsilyl, and acetyl derivatives. The goal was to enable rapid method creation for high-confidence screening and quantitation in forensic laboratories.

Methodology and Instrumentation Used

• Instrument platform: Agilent 7000 Series triple quadrupole GC/MS with extractor electron ionization source
• Chromatographic setup: Agilent Ultra Inert multimode inlet in pulsed splitless mode, J&W DB-5ms column (30 m × 0.25 mm, 0.25 µm), retention time locked to cocaine at 12.26 min
• Oven program: 80 °C (1 min hold), ramp at 20 °C/min to 290 °C (8 min hold), helium carrier gas at constant flow
• MRM development: full scan acquisition (m/z 100–450) in MassHunter Optimizer software to identify precursors and products, followed by automated collision energy optimization
• Database output: 1 803 optimized MRM transitions with 3–12 transitions per compound, associated collision energies, relative abundances, and retention times

Main Results and Discussion

The resulting database covers benzodiazepines, antidepressants, opioids, drugs of abuse, and their metabolites. Application to authentic postmortem blood demonstrated that fentanyl at 1.7 ng/mL was readily detected by the MRM method, whereas full scan deconvolution failed to identify it. The curated transitions improved sensitivity and selectivity, reducing false negatives. Integration with MassHunter data acquisition allows time-segment or dynamic MRM methods, with optional concurrent full scan for retrospective analysis and matrix assessment.

Benefits and Practical Applications of the Method

• Automates method development, saving time and resources
• Enhances detection of trace-level toxicants in complex biological samples
• Facilitates high-throughput targeted screening and reliable quantitation
• Supports instrument-to-instrument reproducibility through retention time locking

Future Trends and Applications

Expansion of the database to include emerging novel psychoactive substances will further strengthen forensic capabilities. Coupling with high-resolution mass spectrometry and predictive retention time models could enable hybrid workflows combining targeted MRM screening with non-targeted compound discovery. Integration with shared open-access spectral libraries and machine learning algorithms for transition prediction will accelerate method development and adaptation to new threats.

Conclusion

The established GC/TQ MRM database provides a robust, sensitive, and reproducible framework for forensic toxicology screening and quantitation. Its modular design and automated development workflow address evolving toxicant challenges and enable rapid, high-confidence analyses in forensic and clinical laboratories.

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