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

Significance of the Topic

The ability to detect a broad range of toxicants in complex biological samples underpins advances in clinical and forensic research. High-sensitivity, targeted MRM screening streamlines workflows and enhances confidence in identifying low-abundance compounds in matrices such as urine and postmortem specimens.

Objectives and Study Overview

This study evaluates the performance gains achieved by migrating an established targeted MRM method from the Xevo TQD to the new Xevo TQ-S micro mass spectrometer coupled with an ACQUITY UPLC I-Class system. Key aims include:

• Comparing true positive detection rates across platforms
• Assessing sensitivity improvements for critical analytes
• Demonstrating applicability to routine clinical research testing

Methodology

Commercially available urine reference controls were diluted five-fold in aqueous mobile phase and centrifuged prior to triplicate UPLC-MS/MS injections. The gradient separation used a C18 column at 50 °C with a 0.4 mL/min flow rate. Preconfigured MRM transitions targeted 178 compounds, applying qualifier and quantifier channels per analyte. Data were processed automatically with the TargetLynx Application Manager, adjusting area thresholds to account for the higher signal response of the TQ-S micro.

Instrumentation Used

• ACQUITY UPLC I-Class system with FTN autosampler
• ACQUITY UPLC HSS C18 column (1.8 µm, 2.1 × 150 mm)
• Xevo TQ-S micro triple quadrupole mass spectrometer
• Electrospray ionization in positive mode with 3 kV capillary voltage, 400 °C desolvation temperature, and 800 L/hr gas flow

Main Results and Discussion

Both platforms identified expected analytes in negative and positive control samples, but the Xevo TQ-S micro demonstrated superior sensitivity. In addition to matching detections on the Xevo TQD, the new system uniquely identified α-hydroxyalprazolam and lorazepam in specific controls. Analysis of a low-level benzodiazepine panel revealed five additional compounds at 75 ng/mL, below standard cut-off thresholds. The increased number of scans per function, enabled by advanced electronics, underlies improvements in precision, reproducibility, and sensitivity.

Benefits and Practical Applications

The combined UPLC-MS/MS platform delivers a single-run solution for qualitative screening and quantitative confirmation across diverse biological matrices. Enhanced detection limits support early identification of trace toxicants, reducing false negatives and improving laboratory efficiency.

Future Trends and Opportunities

Ongoing developments may expand targeted panels to include emerging contaminants and metabolites. Integration with high-resolution, non-targeted workflows and automated data analytics will further elevate throughput and confidence in clinical and forensic settings. Regulatory alignment and standardized protocols will drive broader adoption.

Conclusion

The ACQUITY UPLC I-Class coupled with the Xevo TQ-S micro significantly enhances targeted MRM screening performance, offering higher sensitivity, robust reproducibility, and versatile application in clinical research toxicology.

References

1. Roberts M, Lee R, Wood M. Targeted MRM Screening for Toxicants in Biological Samples by UPLC-MS/MS. Waters Application Note. 2009.
2. Rosano T, Wood M, Swift T. Postmortem Drug Screening by Non-Targeted and Targeted UPLC-MS Technology. Journal of Analytical Toxicology. 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. 2013.
4. Waters Corporation. Xevo TQ-S micro Product Brochure. 2014.
5. European Workplace Drug Testing Society. Guidelines for Urine Confirmation Tests. EWDTS; accessed January 2016.