Field Sampling for Pesticides, Using Solid Phase Microextraction/Capillary GC

Significance of the Topic

Solid phase microextraction (SPME) coupled with capillary gas chromatography streamlines environmental monitoring of pesticide residues by eliminating bulk sample containers, reducing handling steps, and enhancing analyte stability during storage.

Objectives and Study Overview

This study evaluated a portable SPME field sampler for direct water sampling of various pesticide classes, including chlorinated, organophosphorus, and triazine compounds. It focused on method validation, storage stability on the fiber, and comparison with traditional glass and plastic containers.

Methodology

• Sample preparation: 4 mL water containing 25 % NaCl, adjusted to pH 8.
• Extraction: direct immersion SPME for 20 minutes with constant stirring.
• Desorption: thermal desorption at 260 °C for 10 minutes in a GC injector.
• Analytes: chlorinated pesticides (lindane, DDE, heptachlor epoxide, endrin ketone, methoxychlor), organophosphorus pesticides (parathion, methyl parathion, malathion, phorate, disulfoton, sulfotep, famphur, TEPP, thionazin), and triazines (atrazine, simazine).

Used Instrumentation

• SPME Portable Field Sampler equipped with 100 µm PDMS fiber (Cat. No. 504823).
• SPME Portable Field Sampler equipped with 75 µm Carboxen/PDMS fiber (Cat. No. 504831).
• Capillary gas chromatograph with thermal desorption inlet.

Main Results and Discussion

Analyte stability on the SPME fiber was substantially higher than in conventional water storage. After 24 hours at 4 °C, average losses on the fiber were below 10 %, compared to over 70 % in both glass and plastic containers. Even at room temperature, fiber-stored samples showed only 15 % average loss versus nearly 80 % in bulk water. These findings highlight the risks of off‐site sample transport and the benefits of field extraction.

Benefits and Practical Application of the Method

• Minimized sample logistics: no need for multiple vials or preservatives.
• Enhanced analyte retention: stable storage of low‐volatility and volatile pesticides.
• Reduced solvent use and waste management.
• Improved accuracy and reproducibility in environmental pesticide analysis.

Future Trends and Possibilities of Application

Advances may include novel fiber coatings for broader analyte ranges, integration of field samplers with portable GC/MS units, and automated samplers for sequential deployments. Extension to soil, air, and food matrices, as well as real‐time on‐site analysis using miniaturized detectors, will expand SPME utility.

Conclusion

The portable SPME field sampler provides a robust solution for direct extraction and storage of pesticides, greatly reducing analyte loss compared to traditional sampling containers and simplifying environmental monitoring workflows.

References

• Shirey R. Field Sampling for Pesticides Using Solid Phase Microextraction/Capillary GC. The Supelco Reporter. 1997;16(5):5–6.