ACQUITY™ UPLC™ I-Class/Xevo™ TQD IVD System: Analytical Performance for Antidepressant Drugs

Significance of the Topic

The accurate quantification of antidepressant drugs in human plasma is essential for therapeutic drug monitoring, pharmacokinetic studies, and ensuring patient safety. High-performance analytical methods support clinical decision making and regulatory compliance, particularly when dealing with compounds that require precise detection at low concentrations.

Objectives and Study Overview

This application note evaluates the analytical performance of the Waters ACQUITY UPLC I-Class/Xevo TQD IVD System for a panel of ten antidepressant compounds. The study aims to demonstrate system suitability for routine analysis in clinical and research laboratories by assessing sensitivity, selectivity, linearity, and precision.

Methodology and Instrumentation

Sample Preparation:

• Aliquot of 50 µL plasma per sample
• Protein precipitation with acetonitrile
• Centrifugation and dilution with water prior to injection

Chromatographic Conditions:

• Column: XSelect Premier HSS T3 (2.5 µm, 2.1 × 100 mm)
• Mobile phase A: 2 mM ammonium acetate in water
• Mobile phase B: 2 mM ammonium acetate in methanol
• Flow rate: 0.4 mL/min initially, increased to 0.6 mL/min during wash step
• Gradient: 40% A to 20% A over 4 minutes, wash at 100% B, re-equilibration to 40% A by 5 minutes

Mass Spectrometry Conditions:

• System: Xevo TQD IVD with ESI positive mode
• Acquisition: Multiple Reaction Monitoring (MRM)
• Resolution: 0.75 FWHM for both MS1 and MS2 stages

Software:

• MassLynx v4.2 for instrument control
• TargetLynx XS for data processing

Main Results and Discussion

The system achieved excellent chromatographic separation and selectivity across all ten analytes, as evidenced by well-resolved peaks and minimal matrix interferences. Calibration models attained correlation coefficients (r2) greater than 0.995, with most analytes requiring quadratic fitting and two analytes exhibiting linearity.

• Lower Limit of Quantification (LLOQ): Signal-to-noise ratios above 10, bias ≤ 15% (except fluoxetine at 17.6%)
• Precision: %RSD ≤ 20% at LLOQ over five runs (n = 50)
• Total precision and repeatability: assessed with quality controls over five occasions (n = 25)

These performance metrics confirm the system’s robustness for trace-level detection and reliable quantification in plasma matrices.

Benefits and Practical Applications

The evaluated UPLC-MS/MS platform offers:

• Rapid analysis cycle (< 5 minutes per injection) supporting high throughput
• High sensitivity suitable for therapeutic drug monitoring and pharmacokinetic profiling
• Broad dynamic range accommodating various dose levels
• User-friendly software for streamlined method development and data review

This method can be implemented in clinical diagnostic labs, pharmaceutical research, and quality control environments for monitoring antidepressant therapies.

Future Trends and Opportunities

Advances in multiplexed UPLC-MS/MS workflows may enable simultaneous monitoring of larger drug panels. Integration with automated sample handling and machine learning–driven data analysis promises enhanced throughput and predictive insights. Expansion to dried blood spot sampling and point-of-care mass spectrometry could further broaden clinical applications.

Conclusion

The ACQUITY UPLC I-Class/Xevo TQD IVD System demonstrates excellent analytical performance for a comprehensive panel of antidepressants in plasma. Its combination of speed, sensitivity, and reproducibility makes it a valuable tool for both clinical and research settings, facilitating accurate drug quantification and supporting patient care.