Single-stage Extract Clean-up in Pesticides' Determination Using Agilent EnviroPrep

Importance of the topic

Analytical methods for pesticide determination require effective removal of high molecular weight matrix components such as lipids and resins that interfere with gas chromatographic analysis. Gel permeation chromatography offers a one stage clean up to extend column lifespan and improve the sensitivity and reproducibility of trace level pesticide measurements in complex environmental and biological samples.

Objectives and Study Overview

This application note evaluates the performance of single stage extraction clean up using Agilent EnviroPrep preparative GPC columns. The goal is to demonstrate efficient separation of high molecular weight interferences from target pesticide analytes in soil and tissue extracts, following EPA Method SW846-3640 guidance and US EPA CLP requirements.

Methodology

The sample extraction was performed using dichloromethane, with the option to employ a greener eluent mixture of ethyl acetate and cyclohexane. A five component test mixture containing corn oil 25000 mg/L, bis 2 ethylhexyl phthalate 1000 mg/L, methoxychlor 200 mg/L, perylene 20 mg/L and elemental sulfur 80 mg/L was used to assess column performance.

Instrumentation

• Agilent EnviroPrep GPC columns two columns 300 x 25 mm
• Agilent 1260 Infinity GPC SEC System
• Agilent 1260 Infinity Isocratic Pump and Manual Injector
• Agilent 1260 Infinity Variable Wavelength Detector VL at 254 nm

Main Results and Discussion

The chromatographic separation achieved distinct and sharp peaks for all five test components, confirming the column's high resolution and loading capacity > 10 mg on column. The data indicate clear baseline separation between high molecular weight interferences and low molecular weight pesticides. Operating at 10 mL/min and pressures up to 150 bar, EnviroPrep columns exhibit robust mechanical stability and high throughput potential.

Benefits and Practical Applications

• Efficient removal of lipids, natural resins and polymers prior to GC/MS analysis
• Extended GC column lifetime and improved chromatographic efficiency
• High sample loading capacity for trace level pollutant detection
• Adaptability to various organic matrices including soil and animal tissue

Future Trends and Potential Applications

Future developments may focus on reducing solvent usage through optimized eluent systems, integrating automated sample preparation, coupling GPC clean up directly to mass spectrometers, and expanding the approach to emerging contaminants such as microplastics and polar pesticide metabolites.

Conclusion

Agilent EnviroPrep preparative GPC columns provide a rapid and robust single stage clean up for pesticide analysis. Their high resolution and loading capacity streamline sample preparation workflows, enhance analytical performance, and comply with regulatory methods for environmental monitoring.

References

1. US EPA Method SW846-3640 and US EPA CLP Statement of Work Document OLM01.0
2. A Khoshaband and R Teasdale Journal of Chromatography 660 195-198 1994