Determination of multiple pesticide residues in animal foods using on-line gel permeation chromatography-gas chromatography/mass spectrometry

Importance of the Topic

Monitoring pesticide residues in animal-derived foods is critical for ensuring food safety, consumer protection and compliance with regulatory limits. The complexity of fatty matrices demands robust cleanup strategies to achieve accurate multi-residue analysis.

Study Objectives and Overview

This work aimed to develop and validate a rapid, automated method combining a modified QuEChERS extraction with on-line gel permeation chromatography (GPC) coupled to gas chromatography/mass spectrometry (GC/MS) for simultaneous determination of 21 pesticides in animal food samples.

Methodology and Instrumentation

The sample preparation workflow involved:

• Homogenizing 3 g of sample with 5 g water followed by extraction in acetonitrile (n-hexane saturated) and n-hexane (acetonitrile saturated) with added NaCl.
• Phase separation by centrifugation and cleanup of 2 mL supernatant with MgSO₄, C18 and PSA sorbents.
• Final extract introduction into an on-line GPC system for removal of fats and pigments prior to GC/MS analysis.

The instrumental setup comprised:

• GPC: Shodex CLNpak EV-200 column (2×150 mm), mobile phase acetone/cyclohexane (3:7, v/v) at 0.1 mL/min and 40 °C oven.
• GC/MS: Rxi-5ms analytical column (0.25 mm×30 m, 0.25 μm), PTV injector with temperature ramp, temperature-programmed oven (82 °C to 300 °C) and selected ion monitoring for target analytes.

Results and Discussion

The method provided clear chromatographic separation of target pesticides with minimal matrix interference. Validation in pork and shrimp matrices at a 0.02 mg/kg spike level yielded:

• Recoveries ranging from 72.9% to 118.6%
• Relative standard deviations below 10%
• Limits of detection between 0.6 and 2.5 µg/kg; limits of quantification between 2.0 and 8.4 µg/kg
• Calibration linearity (10–500 µg/L) with correlation coefficients above 0.998

Benefits and Practical Applications

This automated on-line GPC-GC/MS approach reduces sample handling, effectively removes high molecular weight interferences and accelerates the analysis of multiple pesticides in complex animal food matrices. It is well suited for regulatory compliance, quality control and routine monitoring in food laboratories.

Future Trends and Potential Applications

Emerging developments may include:

• Expansion to additional pesticide classes and emerging contaminants
• Integration with high-resolution mass spectrometry for confirmatory screening
• Miniaturized and high-throughput GPC-GC/MS platforms
• Application to diverse food matrices such as dairy and processed meats

Conclusion

The combined QuEChERS and on-line GPC-GC/MS method offers a simple, rapid and reliable solution for comprehensive pesticide residue analysis in animal foods, meeting stringent sensitivity and accuracy requirements.

References

• Y. Ye, X. Liu, S. Zhan, T. Huang, S. Kawano, Y. Hashi. Determination of multiple pesticide residues in animal foods using on-line gel permeation chromatography–gas chromatography/mass spectrometry. Pittcon 2014, 1680-8P, Shimadzu Global COE, Guangzhou, China.