Accurate Identification and Quantification of Pesticide Residues in Ghee

Significance of the topic

Ghee is a widely consumed dairy fat with a high lipid content that can concentrate pesticide residues, posing potential health risks. Reliable detection and quantification of a broad range of pesticides in ghee support food safety compliance and consumer protection. The development of an efficient sample preparation and sensitive analytical workflow is crucial for routine monitoring in quality control laboratories.

Objectives and study overview

This study aimed to establish a robust method for the simultaneous determination of over 150 pesticide residues in ghee. Key goals included achieving low limits of quantification, high linearity, and acceptable recovery and precision across multiple pesticide classes. The work integrates a QuEChERS-based extraction and cleanup with tandem GC/MS/MS analysis.

Used instrumentation

• Gas chromatograph: Agilent 8890 GC with multimode inlet, air cooling, and midcolumn backflush
• Mass spectrometer: Agilent 7010 GC/TQ equipped with high-efficiency source
• Column: Agilent J&W HP-5ms ultra inert, 15 m × 0.25 mm × 0.25 µm
• Dispersive cleanup tubes: Part no. 5982-4956CH (150 mg C18, 900 mg MgSO₄)

Methodology

Samples of liquefied, homogenized ghee (2 g) were acidified with 0.1% acetic acid in water and extracted with 10 mL acetonitrile. QuEChERS extraction salts were added, followed by centrifugation. The supernatant underwent dispersive cleanup with C18 sorbent and MgSO₄, then was diluted and injected (2 µL splitless) into the GC/MS/MS. Multiple reaction monitoring (MRM) transitions were selected from an Agilent P&EP database to ensure specificity. Calibration used matrix-matched standards over 0.25–25 ng/g with 1/x weighting.

Main results and discussion

• Instrument LOQs ranged from 0.25 to 2.5 ng/g, meeting regulatory requirements.
• Calibration curves exhibited excellent linearity (R² > 0.98) for all targets.
• Average recovery values were 70–130% at fortification levels of 2.5, 5, and 10 ng/g, with repeatability %RSD <20%.
• Dispersive C18 cleanup effectively removed co-extracted lipids, reducing interference in the 9–14 min retention window.

Benefits and practical applications

This approach provides:

• High-throughput analysis suitable for routine quality control of dairy fats.
• Trace-level sensitivity to comply with maximum residue limits set by food safety authorities.
• Wide pesticide scope covering organochlorines, organophosphates, pyrethroids, and others.

Future trends and potential applications

Advancements may include automation of QuEChERS workflows, integration with high-resolution mass spectrometry for non-target screening, and extension to other lipid-rich matrices such as butter, cheese, and dietary supplements. Machine learning algorithms could further improve data processing and compound identification.

Conclusion

The combined QuEChERS extraction, dispersive C18 cleanup, and GC/MS/MS method successfully quantified over 150 pesticides in ghee with low ng/g detection limits, strong linearity, and reliable recovery and precision. This workflow meets food safety standards and supports efficient monitoring of pesticide residues in fatty matrices.

References

• Ministry of Fisheries, Animal Husbandry & Dairying. Milk Production in India: The Journey of India's Dairy Sector. Press Information Bureau. 2025.
• Food Safety and Standards Authority of India. Food Safety and Standards (Food Products Standards and Food Additives) Regulations, 2011. Version-XII. 2020.
• Ulambayar N-E, Smanalieva J, Hellwig A, Iskakova J, Choijilsuren N, Kalemshariv B, Vankhuu E. Nutritional Composition of Ghee of Various Animal Origins Produced in Some Silk Road Countries. Journal of Food Composition and Analysis. 2024;132:106251.