Small but Powerful: Antiepileptic Drugs in Human Serum Analyzed with a Miniature Triple Quadrupole Mass Spectrometer in Research

Significance of the Topic

Liquid chromatography tandem mass spectrometry (LC MS MS) is a cornerstone in analytical laboratories for its high selectivity and sensitivity. Monitoring antiepileptic drug concentrations in serum supports therapeutic drug management, clinical research, and quality control. A compact instrument retaining full performance addresses space constraints in modern laboratories.

Objectives and Study Overview

This work assesses the analytical performance of a miniature triple quadrupole mass spectrometer (Agilent Ultivo LC/TQ) for quantifying 15 antiepileptic drugs in human serum. Results are benchmarked against those from a conventional full-size LC/TQ (Agilent 6470) over a wide concentration range (0.59 ng/mL to 20 000 ng/mL).

Methodology and Instrumentation

• Sample Preparation
  • Human serum spiked with drug standards and internal standards.
  • Protein precipitation with methanol, centrifugation, and 1:10 dilution of supernatant in water.
• Liquid Chromatography
  • Column: Agilent Poroshell 120 EC-C18 2.1×100 mm, 2.7 μm, with guard column.
  • Mobile phases: water and methanol, each containing 2 mM ammonium acetate.
  • Flow rate: 0.4 mL/min; injection volume: 4 μL; column temperature: 50 °C; autosampler at 4 °C.
  • Run time: 8 min plus 1 min post time.
• Mass Spectrometry
  • Electrospray ionization in positive mode.
  • Gas temperature and sheath gas temperature: 350 °C; gas flow: 12 L/min; sheath gas flow: 11 L/min; nebulizer pressure: 50 psi.
  • Capillary voltage: 3500 V; nozzle voltage: 0 V; Delta EMV: 0 V.
• Comparison Instrument: Agilent 6470 triple quadrupole using identical LC parameters.

Key Results and Discussion

• Calibration and Linearity
  • Calibration curves spanned 0.59–20 000 ng/mL with R2 values above 0.994.
  • Ten analytes exhibited linear response; five required quadratic fitting for full dynamic range.
• Accuracy and Precision
  • Both systems achieved accuracy within ±20% at the lowest calibration level and precision (CV) below 15% across all levels.
  • Representative chromatograms at LOQ and ULOQ confirmed reproducible retention times and peak shapes.
• Comparative Performance
  • The compact Ultivo delivered sensitivity and dynamic range comparable to the full-size 6470 instrument.

Benefits and Practical Applications

• Reduced instrument footprint ideal for space-limited labs.
• Preserved analytical performance supports therapeutic drug monitoring and pharmacokinetic research.
• Fast 8-minute analysis time enables high throughput.

Future Trends and Possibilities

Future work may explore matrix effect evaluations, expand the drug panel, and integrate automated sample preparation to increase throughput and robustness. The miniaturization concept can be generalized to other therapeutic classes and complex matrices.

Conclusion

The Agilent Ultivo LC/TQ compact mass spectrometer demonstrated analytical performance equivalent to a conventional full-size triple quadrupole system for antiepileptic drug quantitation in human serum. Its small footprint combined with high sensitivity and dynamic range makes it an attractive option for clinical and research laboratories.

Reference

• Frick LE, Miller VP. Simultaneous LC MS MS Quantitation of 20 Antiepileptic Drugs in Human Serum. Poster presented at MSACL January 23–26, 2017; Palm Springs CA.