Characterization of Triacylglycerols in Edible Oils Using the ACQUITY UPC2 System and Mass Spectrometry

Importance of the Topic

Edible oils and fats are composed mainly of triacylglycerols (TAGs), whose detailed profiling is essential for quality control, authenticity assessment, and nutritional evaluation. Conventional techniques such as high-temperature gas chromatography and non-aqueous reversed-phase liquid chromatography face challenges including long analysis times, column degradation, and the use of toxic solvents. An alternative approach that delivers rapid, high-resolution separation coupled with structural identification is highly desirable in food analysis and lipid research.

Study Objectives and Overview

This work evaluates the performance of the ACQUITY UPC2 System combined with time-of-flight mass spectrometry (Xevo G2 QTof with MS E) for efficient separation and identification of TAGs in peanut, sunflower seed, and soybean oils. The goals are to achieve baseline resolution of major TAG species within a reduced timeframe and to establish reliable identification protocols based on accurate mass and fragment ion data.

Methodology and Instrumentation

Separation was performed on an un-endcapped C18 UPC2 column (3.0 x 150 mm, 1.8 μm) using compressed CO2 and acetonitrile gradient elution at 1.0 mL/min, 20 °C, and 1500 psi back pressure. Post-column, methanol with 10 mM ammonium hydroxide was introduced at 0.2 mL/min to enhance electrospray ionization. Mass detection employed QTof MS with MS E acquisition to record both precursor and high-energy fragment spectra for unambiguous TAG assignment.

Main Results and Discussion

All major TAGs in the three oils eluted within 15 minutes with baseline separation, outperforming the 30–80 minute runtimes of conventional methods. Accurate mass measurements of ammoniated molecular ions and diagnostic diacylglycerol fragments enabled precise structural annotation. Retention behavior followed established trends based on carbon number and degree of unsaturation. An empirical equivalent carbon number (ECN) equation was derived (R2 = 0.99) to predict retention factors, incorporating individual contributions of oleic, linoleic, and linolenic acid residues.

Benefits and Practical Applications

• Rapid, high-resolution TAG profiling supports routine quality control in food and oil industries.
• Reduced solvent consumption and lower operating pressures enhance sustainability and instrument longevity.
• High-resolution MS E data provide structural insights even in the absence of reference standards.

Future Trends and Applications

Further developments may include coupling UPC2 with ion mobility for stereoisomer separation, expanding lipidomics workflows to cover minor components, and integrating artificial intelligence for automated peak annotation. Ongoing efforts toward greener mobile phases and ultra-high throughput platforms will broaden the applicability of convergence chromatography in industrial and academic laboratories.

Conclusion

The ACQUITY UPC2 System, when paired with Xevo G2 QTof MS and MS E technology, enables fast, efficient, and comprehensive TAG analysis in edible oils. This approach addresses limitations of traditional methods, offering enhanced throughput, structural confidence, and reduced environmental impact.

References

1. D. Marini, in Food Analysis by HPLC, 2nd ed., Marcel Dekker, 2000, pp. 169.
2. AOAC Official Method 993.24, AOAC International.
3. M. Buchgraber, F. Ulberth, E. Anklam, J. Agric. Food Chem., 2000, 48, 3359.
4. K. L. Ross, S. L. Hansen, T. Tu, Lipid Technology, 2011, 23, 14.
5. P. J. Lee, C. H. Phoebe, A. J. Di Gioia, Waters Application Note No. 720002025en, 2007.
6. I. Edwards, J. Kirk, J. Williams, Waters Application Note No. 720004738EN, 2013.