Oasis® Sample Extraction Products for Agrochemical and Environmental Analysis

Significance of Topic

Solid-phase extraction is essential for preparing environmental and agrochemical samples prior to chromatography. Efficient removal of interferences and concentration of trace contaminants enable reliable analysis of pesticides, herbicides, endocrine disruptors and natural products in water, soil and food matrices.

Study Objectives and Overview

This application note presents Waters Oasis sample extraction products — HLB, MCX and MAX — and demonstrates their performance for a wide polarity range of analytes. A series of generic and optimized methods illustrate sample loading, washing and elution steps, recovery data, breakthrough volumes and comparative benchmarks against traditional C18 silica cartridges.

Methodology and Instrumentation

Extraction protocols utilize cartridges packed with water-wettable HLB copolymer or mixed-mode ion-exchange sorbents. Typical steps include conditioning (organic solvent and aqueous buffer), sample loading (100 mL to 1 L), sequential washes to remove matrix components, and elution with solvent blends optimized by pH and polarity. Instrumentation for analysis comprises liquid chromatography (Waters Alliance Separations Module with XTerra or Symmetry C18 columns, PDA or MS detection via Waters/Micromass ZMD ESI interface) and gas chromatography (FID or NPD detectors) following solvent exchange.

Main Results and Discussion

Oasis HLB cartridges deliver higher retention factors for polar analytes such as salicylic acid, theobromine and acetaminophen compared to C18. Breakthrough studies show 400 mL capacity at 2% phenol loss versus 200 mL for conventional phases. Generic HLB methods yield 85–120% recovery (RSD < 13%) for acidic herbicides in tap and well water at sub-µg/L levels. Optimized HLB protocols achieve 80–120% recovery for endocrine disruptors at low ppt. MAX sorbents concentrate acidic compounds like naptalam and phthalic acid with 73–76% recovery in complex matrices. MCX methods recover atrazine metabolites (75–107% with RSD < 8%) and basic fungicides (82–96%, RSD < 10%). Applications for natural products include > 80% isolation of alkaloids, phenolics and flavonoids from botanical extracts.

Benefits and Practical Applications

• Broad polarity range allows one sorbent to replace multiple phases.
• High sample throughput with reduced solvent and time requirements.
• pH-tolerant polymeric sorbents enable selective ion-exchange workflows.
• Compatibility with LC/UV, LC/MS and GC detectors for routine QA/QC and research.

Future Trends and Potential Applications

Ongoing developments target miniaturized formats for microflow and automated platforms, coupling SPE microcartridges to high-resolution mass spectrometry. Expansion into real-time monitoring and on-site sample preparation will enhance environmental surveillance and regulatory compliance.

Conclusion

Waters Oasis HLB, MCX and MAX SPE products offer versatile, high-capacity extraction solutions across agrochemical, environmental and natural product applications. Their reproducible recoveries, ease of use and compatibility with modern chromatographic systems make them a valuable tool for trace-level analysis.

Instrumention

• Waters Alliance Separations Module
• Waters XTerra MS C18 and Symmetry C18/RP18 columns
• Waters/Micromass ZMD MS with ESI interface
• GC with FID and NPD detectors
• PDA detection at 230 nm, 254 nm and 330 nm

Reference

• Patent No. 5,882,521; 5,976,376; 6,106,721; 6,254,780; 6,322,695; additional patents pending
• Michael S. Young, Waters Column VI(5), 1997