Rapid Analysis of Anticoagulants in Plasma Using LC-MS/MS

Rapid LC-MS/MS Analysis of Eight Anticoagulants in Plasma — Summary

Significance of the topic

The quantification of anticoagulants in plasma is critical for pharmacokinetic studies, therapeutic drug monitoring, toxicity assessment and clinical research. High-throughput and robust analytical methods reduce turnaround time and support studies that process large numbers of samples, such as population pharmacokinetics and clinical trials. Achieving rapid cycle times without compromising accuracy, precision and low carryover is essential for routine and regulated bioanalysis.

Study objectives and overview

• Develop and demonstrate an ultra-high-speed LC-MS/MS workflow for simultaneous quantification of eight anticoagulants in human plasma.
• Minimize sample preparation to a simple protein precipitation protocol to maximize throughput.
• Leverage advanced HPLC pump and autosampler features to maintain chromatographic reproducibility and suppress carryover within a 2.45 min cycle time (including column equilibration).
• Evaluate method performance by calibration linearity, accuracy and precision across relevant concentration ranges and assess carryover mitigation via internal/external needle rinsing.

Sample preparation and calibration strategy

• Target analytes: apixaban, rivaroxaban, edoxaban, dabigatran, betrixaban, argatroban, acenocoumarol and warfarin.
• Preparation: spike anticoagulants into human plasma. Add stable isotope-labelled internal standards for each analyte (added at 100 µg/L in solution).
• Simple deproteinization: to 50 µL plasma add 25 µL internal standard solution, then 350 µL acetonitrile:methanol (8:2). Vortex 1 min, centrifuge at 20,000 × g for 12 min, transfer 200 µL supernatant to vial.
• Calibration range: typically 10–500 µg/L for DOACs/NOACs (except acenocoumarol and warfarin, which used 100–5000 µg/L). QC levels: LLOQ, Low, Middle and High (10, 20, 200, 400 µg/L or the higher range for coumarin anticoagulants).

Used instrumentation

• Ultra-high-performance liquid chromatograph: Nexera X4 (Shimadzu) — low-dispersion pump with four independently actuated plungers and pressure-feedback control to reduce pulsation and improve solvent delivery responsiveness.
• Autosampler: SIL-40C X4 with high-speed internal and external needle rinsing to perform rinsing and equilibration within the short analysis cycle, reducing carryover risk.
• Mass spectrometer: LCMS-8060RX triple quadrupole, ESI positive mode, MRM detection. Typical interface voltage 1.0 kV; interface temp 400°C; DL temp 200°C; drying gas 5 L/min; nebulizing gas 3 L/min; heating gas 15 L/min; block heater 400°C.
• Column: Shim-pack NovaCore C18-HB, 50 mm × 2.1 mm I.D., 1.7 µm, column temperature 50°C.
• Chromatographic conditions: injection 1 µL; mobile phase A = 5 mmol/L ammonium formate + 0.1% formic acid (water); B = 5 mmol/L ammonium formate + 0.1% formic acid in MeOH:water (9:1); flow program 0.5 mL/min (0–1.50 min) → 0.8 mL/min (1.51–2.00 min) → 0.5 mL/min (2.01–2.45 min). Gradient: B 5% (0.00–0.20 min) → 98% (1.20–2.00 min) → 5% (2.01–2.45 min).
• Sample loop / injection details: sample loop 15 µL; fast internal & external rinse mode enabled for autosampler.

Method performance and key results

• Analysis cycle time: 2.45 minutes including column re-equilibration, enabling high sample throughput.
• Linearity: Calibration curves for all analytes demonstrated excellent linearity across specified ranges with R² values ≈0.999.
• Sensitivity: LLOQ typically 10 µg/L for DOACs and other targeted anticoagulants; acenocoumarol and warfarin used LLOQ = 100 µg/L reflecting their calibration range.
• Accuracy and precision: QC accuracy within 100 ± 15% and precision (%CV) ≤15% across QC levels (six replicate analyses), meeting conventional bioanalytical validation criteria.
• Carryover control: High-speed internal and external needle rinsing and needle-line equilibration were executed within the assay cycle, effectively minimizing carryover while retaining the short cycle time.

Discussion and practical benefits

• Throughput and responsiveness: The Nexera X4 pump design (four independent plungers + pressure feedback) reduced pump-induced pulsation and internal dispersion, supporting reliable retention time repeatability even at very short gradient times.
• Minimal sample prep: Simple protein precipitation reduces labor and consumables, making the workflow suitable for large studies and routine assays where sample numbers are high.
• Robust quantification: The use of stable isotope-labeled internal standards for each analyte corrected matrix effects and signal variability, contributing to the strong accuracy and precision results.
• Carryover mitigation: Fast internal/external rinsing in the autosampler allowed effective reduction of analyte carryover without extending cycle time, important for assays with high concentration variability.
• Applicability: The method is directly applicable for pharmacokinetic studies, high-throughput bioanalysis, and potentially for clinical research settings where rapid turnaround is required (subject to regulatory and clinical validation for diagnostic use).

Future trends and potential applications

• Automation and sample handling: Integration with robotic sample preparation or online SPE could further increase throughput and reproducibility for large-cohort studies.
• Miniaturization and microflow LC: Reducing solvent consumption and improving MS sensitivity through microflow or capillary LC could be explored for lower LLOQs or limited-volume samples.
• High-resolution MS complement: For discovery or untargeted needs, combining rapid targeted quantification with high-resolution MS could support broader profiling of anticoagulant metabolites and impurities.
• Clinical deployment: With full clinical validation and regulatory compliance, accelerated LC-MS/MS workflows could support therapeutic drug monitoring and rapid decision-making in hospital labs.
• Data processing and AI: Automated data review and machine-learning-assisted QC can streamline the evaluation of large datasets generated by ultra-fast methods.

Conclusion

A streamlined LC-MS/MS method combining Nexera X4 UHPLC and the LCMS-8060RX triple quadrupole enables rapid, reproducible quantification of eight anticoagulants from plasma with minimal sample preparation. The approach delivers high linearity, acceptable LLOQs (10 µg/L for most analytes), and meets standard bioanalytical accuracy and precision criteria while maintaining a 2.45 min cycle time. Advanced pump design and high-speed autosampler rinsing are key enablers for balancing throughput with analytical quality.

Reference

• Guideline on bioanalytical method validation and study sample analysis. Ministry of Health, Labor and Welfare, Japan. December 2024 (reference as cited in source document).