Simple and Selective Bioanalytical Plasma Sample Extraction Using Oasis® MCX SPE for High Analyte Recovery

Importance of the Topic

Extracting analytes from biological fluids with high recovery and minimal matrix interference is critical in bioanalytical workflows. Tyrosine kinase inhibitors are widely used in leukemia treatment and require precise quantification in plasma for pharmacokinetic and therapeutic drug monitoring. Mixed-mode ion-exchange SPE streamlines sample preparation, improving accuracy and reproducibility.

Study Objectives and Overview

This study aimed to evaluate a generic protocol using Waters Oasis MCX SPE cartridges to extract multiple tyrosine kinase inhibitors from plasma samples. Key goals included:

• Assessing recovery rates without protocol optimization
• Measuring matrix effects across common TKIs
• Demonstrating method simplicity and selectivity

Methodology and Instrumentation

Mixed-mode cation-exchange SPE was performed using Oasis MCX cartridges. The generic protocol involved:

1. Cartridge conditioning with methanol and aqueous buffer
2. Loading acidified plasma samples to favor cation exchange
3. Washing to remove neutral and anionic interferences
4. Elution of TKIs under basic conditions

Instrumentation

• Waters Oasis MCX solid-phase extraction cartridges
• Standard laboratory centrifuge and vacuum manifold setup

Key Results and Discussion

The SPE protocol yielded average recoveries exceeding 72.6% for all tested TKIs and matrix effects ranging from -3.8% to -11.0%, indicating minimal ion suppression. These results highlight the robustness and selectivity of Oasis MCX SPE for routine bioanalytical workflows, eliminating the need for extensive method development.

Benefits and Practical Applications

• Universal extraction protocol for multiple drugs
• High throughput sample preparation with reduced development time
• Consistent recoveries and low matrix interference suitable for LC-MS/MS analysis
• Applicability to clinical pharmacokinetic studies and therapeutic drug monitoring

Future Trends and Opportunities

• Integration with automated SPE platforms for increased throughput
• Combination with online SPE-LC-MS/MS for direct coupling and reduced hands-on time
• Expansion to other drug classes and metabolites using mixed-mode SPE
• Miniaturized SPE formats for low-volume samples and high-sensitivity assays

Conclusion

The Oasis MCX SPE method offers a simple, selective, and high-recovery approach for extracting tyrosine kinase inhibitors from plasma. Its minimal matrix effects and generic protocol make it an attractive solution for bioanalytical laboratories seeking efficient and reliable sample preparation.

References

• Williams RE, Leatherwood HM. Top 200 Small Molecule Drugs by Retail Sales in 2023. (accessed 21 June 2024).