Targeted MRM Screening Using the ACQUITY UPLC I-Class/Xevo TQ-S micro

Importance of the Topic

Forensic toxicology demands robust screening methods capable of identifying diverse toxicants in complex biological samples. Reliable detection in urine, blood, and postmortem matrices underpins legal investigations, clinical decision making, and workplace compliance.

Study Objectives and Overview

This work assesses the performance of an established targeted MRM screening workflow when migrated to the latest Xevo TQ-S micro mass spectrometer coupled with an ACQUITY UPLC I-Class. The goal is to compare sensitivity, precision, and compound coverage against the previous Xevo TQD platform.

Methodology and Instrumentation

The evaluation employed six commercial urine quality controls, including negative and positive reference materials spiked with certified analyte levels. Samples were diluted fivefold with aqueous mobile phase, vortexed, centrifuged, and directly injected in triplicate. UPLC separation used an ACQUITY UPLC I-Class with FTN autosampler and an HSS C18 column (2.1 × 150 mm, 1.8 µm) at 50 °C. Mobile phases were 5 mM ammonium formate at pH 3.0 (A) and acetonitrile with 0.1 % formic acid (B), at 0.4 mL/min. MS detection employed the Xevo TQ-S micro in ESI positive mode, with source temperature 150 °C, desolvation at 400 °C, and standard cone/desolvation gas flows. A preconfigured MRM panel provided two transitions per compound and optimized voltages and collision energies for 178 analytes. Data processing was automated via TargetLynx with adjusted area thresholds.

Main Results and Discussion

Negative control urines yielded common over-the-counter drug signals on both platforms. In certified positive controls, both instruments detected expected analytes in the S10 panel. The Xevo TQ-S micro additionally identified α-hydroxyalprazolam in one control and lorazepam in another. In a low-level benzodiazepine sample at 25 % cut-off concentration, the new platform resolved five additional benzodiazepines at 75 ng/mL. Enhanced electronics increased scans per function without altering dwell time, boosting sensitivity, reproducibility, and precision.

Benefits and Practical Applications

• Improved qualitative coverage with detection of additional analytes at lower concentrations
• Enhanced precision and reproducibility via increased scan density
• Single UPLC-MS/MS system for both broad screening and high-sensitivity quantitation
• Streamlined workflow with automated data processing

Future Trends and Opportunities

Continued advances in MS electronics and MRM library expansion will further lower detection limits and broaden compound panels. Integration with non-targeted screening, high-throughput automation, and advanced data analytics will support comprehensive toxicology profiling. Customized in-house validation will tailor performance to specific forensic or clinical requirements.

Conclusion

The ACQUITY UPLC I-Class coupled with the Xevo TQ-S micro offers a versatile solution for targeted forensic toxicology screening. Compared to its predecessor, it provides superior sensitivity and precision, enabling detection of additional low-level analytes while maintaining robust quantitative performance.

References

1. Roberts M, Lee R, Wood M. Targeted MRM Screening for Toxicants in Biological Samples by UPLC-MS/MS. Waters Application Note 720002749EN; 2009.
2. Rosano T, Wood M, Swift T. Postmortem Drug Screening by Non-Targeted and Targeted Ultra-Performance LC-MS Technology. J Anal Toxicol. 2011;35:411–423.
3. Roberts M, Wood M. Forensic Toxicology Screening Using the ACQUITY I-Class System with the Xevo TQD. Waters Application Note 720004602EN; 2013.
4. Waters Corporation. Xevo TQ-S micro Product Brochure 720005046EN; 2014.
5. European Workplace Drug Testing Society Guidelines. http://www.ewdts.org (accessed Jan 11, 2016).