Oasis HLB Cartridges and 96-Well Plates

Importance of the Topic

Solid phase extraction with Oasis HLB provides a robust and versatile cleanup and concentration step for acidic, neutral, and basic analytes across a wide polarity range. This method is critical in bioanalysis, environmental testing, food safety, and industrial quality control due to its high retention capacity, pH stability, and compatibility with aqueous and organic samples.

Objectives and Study Overview

This manual aims to describe standardized procedures and optimization strategies for using Oasis HLB cartridges and 96-well plates. It covers sample pretreatment for various matrices, a generic SPE protocol chart, a two-dimensional optimization approach (20-bottle method), and troubleshooting guidelines to maximize analyte recovery and method ruggedness.

Methodology and Instrumentation

Sample pretreatment is classified by matrix type:

• Biological samples: acid or base dilution, protein precipitation, centrifugation and filtration.
• Solid samples: homogenization, solvent extraction, pH or solvent adjustments, centrifugation or filtration.
• Aqueous samples: pH adjustment, use of buffer salts, removal of suspended matter by filtration or centrifugation.
• Non-aqueous liquids: dilution with aqueous buffers and organic co-solvents for reversed-phase or mixed-mode SPE.

General SPE steps:

1. Condition sorbent with methanol.
2. Equilibrate with water.
3. Load sample at controlled vacuum levels.
4. Apply aqueous wash (eg 5% methanol) to remove matrix interferences.
5. Execute optimized secondary wash based on pH and organic ratio.
6. Elute analytes with organic solvent (methanol or modified solvents).
7. Evaporate and reconstitute extracts for analysis.

Instrumentation includes Oasis HLB cartridges or 96-well plates, vacuum manifold, adjustable vacuum pump, centrifuge, and standard pipetting equipment. The plates conform to ANSI microplate dimensions and are compatible with automated robotics.

Key Results and Discussion

Oasis HLB sorbent combines hydrophilic N-vinylpyrrolidone and lipophilic divinylbenzene, offering three times higher retention capacity than traditional silica C18. The generic method achieves recoveries above 85% with RSD below 5%. The 20-bottle optimization allows fine tuning of pH (1–14) and organic solvent percentage to improve selectivity and reduce background noise. The two-dimensional wash-elute strategy ensures cleaner extracts by selectively retaining analytes and removing interferences.

Benefits and Practical Applications

• High and reproducible analyte recovery across diverse sample matrices.
• Wide pH and solvent stability, enabling method flexibility.
• Compatibility with LC-MS/MS for targeted bioanalysis, environmental monitoring, food testing, and industrial QA/QC.
• Automation readiness using 96-well plates and microelution formats to increase throughput and reduce solvent use.

Future Trends and Opportunities

Further advancements may include integration with green solvent systems, coupling with high-resolution mass spectrometry, development of mixed-mode sorbents for enhanced selectivity, and expanded automation for high-throughput applications. Continued method refinement via two-dimensional optimization will support emerging analyte classes and stricter regulatory requirements.

Conclusion

This care and use manual outlines a comprehensive framework for applying Oasis HLB solid phase extraction to a variety of analytical challenges. By following generic protocols and leveraging optimization strategies, analysts can achieve reliable, high-quality data with minimal matrix interference. The robust nature of Oasis HLB supports routine use in diverse industries and research settings.

Reference

No external literature references were provided in the original manual.