Rapid Identification of Double Bond Positions of Lipids in Butter by using Probe ESI Q-TOF LCMS-9050 and OAD-MS/MS

Importance of the Topic

Direct and rapid analysis of lipid double-bond positions is critical for food quality control and lipidomics research. Double-bond location influences nutritional, sensory, and functional properties of fats. Traditional methods require lengthy chromatography or derivatization; combining Probe ESI and OAD with high-resolution MS offers a streamlined approach.

Objectives and Study Overview

This study aimed to demonstrate a fast and simple workflow for locating double bonds in triglycerides extracted from butter. By integrating PESI for direct ionization and OAD-MS/MS fragmentation, the method targets structural elucidation of TG 38:1 and TG 38:2 species.

Methodology and Instrumentation

Brief sample preparation involved extraction of 200 mg butter with 20:80 water/isopropanol and rapid centrifugation. The supernatant was analyzed within five minutes. Analysis employed:

• Probe ESI Q-TOF LCMS-9050 for full-scan MS and CID-MS/MS.
• DPiMS QT coupled with an OAD system via microwave discharge in water vapor for selective cleavage at double bonds.

Main Results and Discussion

• MS-DIAL generated m/z profiles of various TGs in butter; TG 38:1 and TG 38:2 were selected for detailed analysis.
• CID-MS/MS fragments established fatty acyl chain lengths through neutral losses (for example, 16:0, 18:1, 18:2).
• OAD-MS/MS produced characteristic oxyradical-induced fragments adjacent to double bonds, enabling precise location (for example, n-9 position for 18:1, n-6/n-9 for 18:2).
• High-resolution TOF data confirmed fragment assignments with sub-ppm mass accuracy.

Benefits and Practical Applications

The combined PESI-OAD approach streamlines lipid structural analysis without extensive chromatography. It enables rapid profiling of food lipids for quality control, authenticity testing, and lipidomic research, offering high specificity for double-bond localization.

Future Trends and Opportunities

With ongoing advances in ambient ionization and radical-driven fragmentation, this strategy can be extended to complex lipid matrices and other unsaturated compounds. Integration with machine learning based spectral interpretation may further enhance throughput and automation.

Conclusion

This work demonstrates that PESI coupled with OAD-MS/MS on a Q-TOF platform provides a rapid, reliable, and minimal-preparation method to pinpoint double-bond positions in triglycerides. This workflow holds promise for routine lipid analysis in food and biochemical applications.

Instrumentation

• Shimadzu LCMS-9050 with DPiMS QT probe ESI source
• Shimadzu OAD system featuring water vapor microwave discharge