Automated SPE Sample Preparation for Bioanalysis of GLP-1 Analogs from Plasma

Importance of the Topic

Glucagon-like peptide-1 (GLP-1) analogs are key therapeutic agents in diabetes, obesity and cardiovascular health management and are under investigation for neurological applications. Accurate and efficient quantification of these peptides in biological matrices is essential for pharmacokinetic, safety and metabolism studies.

Study Objectives and Overview

This study aimed to develop and validate a fully automated solid-phase extraction (SPE) workflow for the analysis of five GLP-1 analogs (Semaglutide, Exenatide, Liraglutide, Lixisenatide and Tirzepatide) in rat plasma coupled with LC-MS/MS detection. The focus was on improving throughput, reproducibility and compliance while maintaining sensitivity and selectivity.

Methodology and Instrumentation

The protocol begins with protein precipitation of 200 µL plasma using acidified acetonitrile, followed by dilution and loading onto an Oasis PRiME HLB µElution 96-well plate. Elution is performed twice with ammonium hydroxide in acetonitrile and diluted before direct LC-MS/MS injection. Chromatography employs an ACQUITY Premier Peptide CSH C18 column (2.1 x 50 mm, 1.7 µm) at 65 °C with a water/formic acid and acetonitrile/formic acid gradient. Detection uses a Xevo TQ Absolute mass spectrometer operating in positive ESI and MRM mode. Automated sample handling is achieved with Andrew+ Robot, Pipette+ and Extraction+ Connected Devices under OneLab Software control, with QuanRecovery plates reducing nonspecific binding.

Main Results and Discussion

All five analytes showed linear calibration between 5 and 1000 ng/mL with R2 values exceeding 0.99. Matrix effects were below 20% and recoveries were consistent across manual, assisted and fully automated workflows. Fully automated SPE reduced operator time from 3.5 hours (manual) to approximately 2 hours, while assisted pipetting achieved 1.6 hours. Temperature control emerged as critical to prevent solvent evaporation during elution, suggesting future integration of Peltier-controlled modules.

Benefits and Practical Applications

• Enhanced throughput and reproducibility through automation
• Reduced analyst-related errors and improved traceability with audit-trailed software
• Low matrix effects and high recovery enable reliable pharmacokinetic and metabolism studies
• Cost savings over long-term use due to efficient workflows

Future Trends and Opportunities

Ongoing developments will include evaluation of other Oasis sorbents for optimized peptide recovery, scaling volumes for temperature-controlled devices, and expansion of automated protocols to small molecules and broader peptide classes. Integration of advanced robotics will further streamline bioanalytical workflows.

Conclusion

The automated SPE-LC-MS/MS approach provides a robust, sensitive and high-throughput solution for quantifying GLP-1 analogs in plasma. Combined with OneLab Software and connected devices, it offers traceable, cGLP-compliant workflows ideal for drug development and bioanalysis.

Reference

1. M. Trudeau and A. Scumaci, SPE-LC/MS Bioanalytical Quantification of the Biotherapeutic Peptide Semaglutide from Plasma, Waters Application Note 720008097, 2023.
2. T.S. Lee et al., Novel LC-MS/MS analysis of the GLP-1 analog semaglutide with application to pharmacokinetics and brain distribution studies in rats, Journal of Chromatography B, 1221, Art. no. 123688, 2023.
3. Y. Kim et al., Determination of Liraglutide in Rat Plasma Using Selective Liquid Chromatography-Tandem Mass Spectrometry, Mass Spectrometry Letters, 14(4), 2023.