Determination of Fatty Acid Esters of 2- and 3-Monochloro-1,2-propanediol (MCPD) and Glycidol in Edible Oil Using GC/Triple Quadrupole MS

Significance of the Topic

Monochloropropanediol (MCPD) esters and glycidyl esters are heat-induced contaminants that form in refined edible oils and fats. Upon ingestion, these bound species hydrolyze to free 2-MCPD, 3-MCPD and glycidol, compounds associated with toxicological concerns including carcinogenicity and nephrotoxicity. Reliable detection and quantitation of these esters are essential for food safety monitoring, regulatory compliance and the development of mitigation strategies in oil processing.

Objectives and Study Overview

This work aimed to develop and validate a sensitive, selective and robust gas chromatography–triple quadrupole mass spectrometry (GC/TQMS) method for simultaneous measurement of fatty acid esters of 2-MCPD, 3-MCPD and glycidol in edible oils. The new approach was benchmarked against official methods and applied to a range of commercial oil samples to assess contamination levels across different oil types.

Methodology and Instrumentation

Sample preparation followed AOCS Official Method Cd 29a-13, extracting and derivatizing bound esters with phenylboronic acid. Deuterated internal standards for 2-MCPD, 3-MCPD and glycidyl palmitate were spiked into cold-pressed extra virgin olive oil as matrix blank. Key instrumental conditions:

• Instrument: Shimadzu GCMS-TQ8040 triple quadrupole MS
• Column: 30 m × 0.25 mm × 1.0 µm SH-Rxi-1MS capillary
• Injector: splitless injection, 0.5 µL, 250 °C
• Oven program: 80 °C (1 min) → 10 °C/min to 170 °C (5 min) → 3 °C/min to 200 °C → 15 °C/min to 300 °C (15 min)
• Interface temp: 300 °C; ion source: 230 °C
• MRM transitions optimized for each analyte and internal standard

Key Results and Discussion

Chromatographic separation yielded sharp, well-resolved peaks for deuterated and native analytes with retention times ranging from 18.4 min to 21.7 min. Method validation demonstrated:

• LOD: 0.003 µg for 2- and 3-MCPD; 0.006 µg for glycidol
• LOQ: 0.01 µg for 2- and 3-MCPD; 0.024 µg for glycidol
• Linearity: R2 > 0.998 over eight calibration levels
• Repeatability: peak area RSD < 3%
• Accuracy: recoveries within 100 ± 7%
• Precision: RSD < 10%

Compared to the official AOCS method, this GC/TQMS approach achieved more than three-fold sensitivity improvement. Application to commercial oil samples revealed the highest contaminant levels in palm-containing oils, while olive and mustard oils remained below the LOQ.

Benefits and Practical Applications

The validated GC/TQMS method offers enhanced sensitivity and selectivity, enabling reliable quantitation of MCPD and glycidol esters at trace levels. Its robust performance supports routine quality control, regulatory surveillance and research into processing parameters that influence contaminant formation.

Future Trends and Potential Applications

Emerging directions include extending this analytical platform to other food matrices, automating sample preparation for higher throughput and integrating high-resolution MS for broader contaminant screening. Further studies may focus on real-time process monitoring and assessment of mitigation technologies in industrial refining.

Conclusion

A novel GC/TQMS procedure was successfully developed and validated for simultaneous determination of 2-MCPD, 3-MCPD and glycidol esters in edible oils. The method exhibits superior sensitivity, excellent linearity, precision and accuracy, providing a powerful tool for food safety assessment and industry quality assurance.

References

1. Federation for European Oil and Proteinmeal Industry. 2016. FEDIOL Q&A on 2- and 3-MCPD and Their Esters and Glycidyl Esters.
2. The American Oil Chemists’ Society. 2013. Official Method Cd29a-13: 2- and 3-MCPD Fatty Acid Esters and Glycidol Fatty Acid Esters in Edible Oils and Fats by Acid Transesterification.