Forensic and toxicology screening in human blood using a QTOF mass spectrometer and DIA

Significance of the topic

High-resolution QTOF mass spectrometry enables precise accurate mass measurement and detailed product ion spectra, making it a powerful tool for forensic and clinical toxicology. This approach addresses complex biological matrices and the rapid emergence of novel psychoactive substances, enhancing confidence in compound identification.

Objectives and overview of the study

This work transferred a validated triple quadrupole LC-MS/MS screening method to a high-resolution QTOF platform. The goals were to develop a routine workflow for targeted and non-targeted screening of approximately 1,000 compounds in human blood, and to demonstrate the benefit of combining an in-house curated library with public MS/MS repositories using data-independent acquisition (DIA).

Methodology and instrumentation

• Sample preparation: Blood samples spiked with nine drugs of abuse (5–5,000 ng/mL) were extracted by solid-phase extraction.
• LC separation: Shim-pack Velox Biphenyl column (2.1 × 100 mm, 2.7 µm), binary gradient of water/methanol with 2 mM ammonium formate and 0.002% formic acid, flow rate 0.3 mL/min, 17-minute cycle.
• Mass spectrometry: Shimadzu LCMS-9030 QTOF with external calibration; TOF survey scans (m/z 40–900, 100 ms) and DIA-MS/MS scans (m/z 40–500 and 40–900 ranges, CE spreads 5–55 V, isolation widths 25–35 Da, total cycle ~1.08 s).
• Data processing: Targeted screening of 900 compounds in the Shimadzu Forensic Toxicology Database; identification criteria included accurate mass error (±5 ppm), isotopic pattern, retention time, and spectral matching (dot product scoring).

Main results and discussion

All nine spiked analytes were confidently identified in blood extracts. Key compounds such as methamphetamine and benzoylecgonine produced high similarity index (SI) scores across multiple libraries (Shimadzu, Wiley, HighResNPS), despite varying collision energies and instrument origins. The combined use of TOF survey data and DIA-MS/MS spectra, along with a curated in-house library, increased hit rates and reliability for routine screening.

Benefits and practical applications

• Enables robust targeted and non-targeted toxicology screens for hundreds to thousands of analytes.
• Improves identification confidence by leveraging multiple MS/MS libraries and DIA workflows.
• Adapts to evolving drug landscapes, including novel psychoactive substances.
• Facilitates method transfer from triple quadrupole to high-resolution QTOF systems in forensic and clinical labs.

Future trends and applications

Ongoing expansion of spectral libraries and integration of machine learning for automated library curation and spectral deconvolution will further enhance throughput and identification accuracy. Open-source collaborations will drive rapid updates and broader accessibility for toxicology workflows.

Conclusion

The developed QTOF-based screening approach, combining TOF survey scans, DIA-MS/MS data acquisition, and multi-library spectral matching, provides a versatile, sensitive, and specific solution for routine forensic and clinical toxicology. It meets the demands of complex samples and an expanding universe of analytes.

Instrumentation used

• Shimadzu LCMS-9030 QTOF with ESI in positive and negative modes.
• Shim-pack Velox Biphenyl LC column (2.1 × 100 mm, 2.7 µm).
• LabSolutions Insight data review software with Shimadzu Forensic Toxicology Database and external libraries (Wiley MMHW, HighResNPS).