Fully Automated Sample Preparation for the Analysis of Acidic Pesticides and Drug Residues in Potable and Surface Water

Significance of the Topic

Acidic pesticides and pharmaceutical residues are increasingly detected in surface and drinking water at trace levels and pose risks to human health and ecosystems
Traditional manual sample preparation for trace analysis is laborious, subject to variability, and limits sample throughput
Automation of solid phase extraction and solvent evaporation can enhance reproducibility, reduce hands-on time, and allow around-the-clock operation

Objectives and Overview of the Study

This study evaluates a fully automated workflow for preparing water samples for acidic pesticide and drug residue analysis
Key aims include comparing automated sample cleanup and concentration using the FREESTYLE XANA robotic platform against conventional manual methods and assessing recovery, precision, and potential carryover
Complex mixtures of 16 target analytes spanning pesticide and pharmaceutical classes were spiked into surface and tap water to simulate environmental conditions

Methodology

Filtered water samples were acidified to pH 2.5, spiked with internal standards, and split into manual and automated aliquots
Automated workflow on FREESTYLE XANA encompasses SPE cartridge conditioning, sample loading, cartridge washing, dual-step elution with methanol/acetone, nitrogen-assisted solvent removal to 0.2 mL at 40 °C, and final volume adjustment to 0.5 mL
Manual protocol follows similar SPE steps with preconditioned cartridges, drying under heated nitrogen, single-step elution, and evaporation to 0.1 mL at 100–110 °C
Final extracts are analyzed by reversed-phase UHPLC coupled to QTOF-MS in negative electrospray mode with high-resolution mass detection

Used Instrumentation

• FREESTYLE XANA robotic platform with SPE and EVA modules (LCTech GmbH)
• AutoTrace SPE workstation for initial cartridge conditioning (Caliper Life Science or Dionex)
• Agilent 1290 Infinity UHPLC coupled to 6550 iFunnel QTOF-LC/MS
• Peak Scientific Genius 3010 nitrogen generator
• Magnetic stirrer, pH meter, and nitrogen evaporation bench

Main Results and Discussion

Automated preparation yielded recoveries for most analytes between 80 % and 120 % with coefficients of variation below 5 %, matching or exceeding manual performance
Internal standard responses and absolute peak areas were comparable between methods, confirming equivalent extraction efficiency and quantitation accuracy
No significant carryover (<1 %) was observed in the evaporation chamber due to integrated rinsing steps
Automated parallel processing of up to 24 samples overnight dramatically increases throughput compared to manual handling of six samples

Benefits and Practical Applications

• Enhanced reproducibility and precision through standardized robotic handling
• Significantly increased sample throughput and 24/7 operation
• Reduced reagent loss by automated vial rinsing and precise solvent handling
• Labor cost savings and redeployment of staff to high-value tasks
• Applicable to routine monitoring of environmental water under regulatory frameworks

Future Trends and Possibilities

Integration of high-resolution mass spectrometry with automated sample preparation supports non-target screening and suspect analysis of emerging contaminants
Further miniaturization and multiplexing of SPE cartridges could reduce solvent consumption and lower detection limits
Cloud-based data management and AI-driven method optimization can streamline workflows and adapt protocols dynamically to diverse analyte panels
Expansion to other matrices (wastewater, biological fluids) will broaden environmental and public health applications

Conclusion

The fully automated sample preparation workflow using FREESTYLE XANA demonstrates equivalent or superior extraction performance compared to manual methods, with improved precision, throughput, and operational efficiency
This approach supports robust monitoring of micropollutants in water and aligns with stringent regulatory requirements

References

• European Water Framework Directive 2000/60/EC
• DIN EN ISO 11369:1997-11 (F12): Pesticide analysis by solid-phase extraction
• DIN 38407-35:2010-10 (F35): Micropollutants in water
• Agilent Technologies: 1290 Infinity UHPLC & 6550 iFunnel QTOF-LC/MS specifications
• LCTech GmbH: FREESTYLE XANA automated SPE and evaporation system