Waters Oasis sample preparation - Application Notebook

Importance of the topic

Solid-phase extraction (SPE) is a foundational technique in analytical chemistry for purifying and concentrating analytes from complex matrices. Reliable sample preparation directly impacts sensitivity, accuracy, and robustness of downstream analyses in environmental monitoring, pharmaceutical research, food safety, and bioanalytics.

Goals and study overview

This application notebook documents the development and evolution of the Oasis SPE product line by Waters over three decades. It aims to present how tailored sorbent chemistries and device formats can overcome common SPE challenges—such as breakthrough, sorbent drying, pH restrictions, and silanol interactions—to deliver robust, selective, and sensitive extraction protocols.

Methodology and instrumentation

Key features and techniques include:

• Polymeric sorbents with high purity, reproducibility, and stability across a broad pH range.
• Reversed-phase Oasis HLB (hydrophilic–lipophilic balanced sorbent) introduced in 1996 for generic extractions.
• Mixed-mode ion-exchange sorbents: MCX and MAX (strong cation and strong anion exchangers) in 1999; WCX and WAX (weak exchangers) in 2004.
• Oasis 2×4 Method (2005) for systematic sorbent and protocol selection, yielding highly clean extracts.
• Device formats: cartridges, 96-well plates, on-line SPE columns, and µElution plates enabling elution volumes as low as 25 µL.

Instrumentation highlighted:

• Waters Alliance HPLC systems
• Acquity UPLC platforms
• Quattro Ultima and Quattro Premier tandem mass spectrometers
• Water ZQ and UV detectors

Main results and discussion

The Oasis portfolio demonstrated high recovery rates (>80%) and low matrix interference across multiple analyte classes—from acidic and basic pharmaceuticals to environmental contaminants and biomolecules. Mixed-mode sorbents enabled selective retention and fractionation of acids, bases, and neutrals. The 2×4 Method streamlined method development and reduced matrix effects by up to 50% compared to traditional approaches. µElution plates maintained sensitivity while minimizing solvent usage and sample dilution.

Benefits and practical applications

Adopting Oasis SPE products yields:

• Improved analyte recoveries and reproducibility (RSD <10%).
• Broad applicability across water, plasma, urine, food, and environmental samples.
• Time-saving workflows via 96-well and on-line formats for high-throughput laboratories.
• Reduced solvent consumption with µElution plates and miniaturized protocols.

Future trends and potential applications

Advances are expected in automated on-line SPE coupled directly to UPLC-MS/MS, further miniaturization of sorbent formats, development of novel multimodal polymer phases, and integration with green solvent systems. Emerging applications include single-cell metabolomics, high-throughput screening in drug discovery, and portable SPE devices for field analysis.

Conclusion

The Waters Oasis family represents a versatile and innovative SPE toolkit that addresses common sample preparation challenges. With a suite of sorbent chemistries, device formats, and method development strategies, Oasis enables reliable, efficient, and high-throughput sample cleanup for diverse analytical needs.