Analysis of anti-epileptic drugs in human serum using an Agilent Ultivo LC/TQ

Importance of Topic

The accurate measurement of anti-epileptic drugs in human serum is essential for therapeutic drug monitoring and clinical research. These compounds often occur across orders of magnitude in concentration, requiring assays with high sensitivity, specificity and dynamic range. Compact instrumentation that maintains analytical performance can overcome space constraints in busy laboratories.

Study Objectives and Overview

This study evaluated the performance of the Agilent Ultivo triple quadrupole LC/MS system for simultaneous quantitation of 15 anti-epileptic drugs in human serum. Results were directly compared with those obtained on a larger Agilent 6470 LC/TQ instrument under identical analytical conditions.

Methodology and Instrumentation

Sample Preparation

• Protein precipitation with methanol followed by 10-fold dilution in water
• Calibration standards spiked into serum covering 0.59 ng/mL to 20 000 ng/mL (up to 20 µg/mL)

Chromatography and Mass Spectrometry

• UHPLC using Agilent 1290 Infinity II pump and autosampler with Poroshell 120 EC-C18 guard (2.1 × 5 mm) and analytical column (2.1 × 100 mm)
• Gradient elution (10 to 95 % methanol in 8 min) at 0.4 mL/min, 50 °C
• Dynamic MRM in positive ion mode, two transitions per analyte plus a phospholipid marker
• Source conditions: drying and sheath gas at 350 °C, capillary voltage 3500 V, nebulizer 50 psi

Key Results and Discussion

Linearity and Sensitivity

• All compounds showed R2 values > 0.994 across their respective ranges
• Limits of quantitation on-column as low as 0.05 pg for tiagabine and up to ~23 pg for vigabatrin
• Ten analytes fitted linear models, five required quadratic calibration curves

Accuracy and Precision

• Accuracy within ±20 % at the lowest level
• Reproducibility CVs < 15 % across nine concentration levels

Comparison with Agilent 6470

• Similar signal-to-noise ratios, LOQs and calibration performance
• Compact Ultivo maintained dynamic range and sensitivity

Benefits and Practical Applications

The Ultivo LC/TQ system provides high-throughput, multiplexed quantitation of clinically relevant drugs while occupying minimal bench space. Its robust performance supports therapeutic drug monitoring, pharmacokinetic studies and quality control in pharmaceutical or clinical laboratories.

Future Trends and Applications

Future work may include

• Expanded panels covering additional anti-epileptic or central nervous system drugs
• Assessment of matrix effects in diverse patient populations
• Integration with automated sample preparation and high-throughput workflows
• Advanced data processing for real-time pharmacokinetic modeling

Conclusion

The Agilent Ultivo LC/TQ delivers comparable analytical sensitivity, dynamic range and data quality to a larger LC/TQ system. Its reduced footprint does not compromise performance, making it a viable solution for space-limited clinical research environments.

References

Frick LE; Miller VP. Simultaneous LC/MS/MS Quantitation of 20 Anti-epileptic Drugs in Human Serum. Poster presented at MSACL, January 2017, Palm Springs CA.