The Impact of the Complexing Cation on the Sensitivity of the Collisional-Induced Dissociation Spectra to Fatty Acid Position for a Set of YXY/YYX-type Triglycerides

Pavel Makarov; Dong Zheng; Duc Le; Jason J Evans

doi:10.1002/rcm.8211

The Impact of the Complexing Cation on the Sensitivity of the Collisional-Induced Dissociation Spectra to Fatty Acid Position for a Set of YXY/YYX-type Triglycerides

Rapid Commun Mass Spectrom. 2018 Jun 26. doi: 10.1002/rcm.8211. Online ahead of print.

Authors

Pavel Makarov¹, Dong Zheng², Duc Le¹, Jason J Evans³

Affiliations

¹ University of Massachusetts Boston, Chemistry Dept., 100 Morrissey Blvd, Boston, Massachusetts, United States.
² University of Wisconsin Milwaukee, Department of Mechanical Engineering, College of Engineering and Applied Science, Milwaukee, Wisconsin, United States.
³ Chemistry Department, University of Massachusetts Boston, 100 Morrissey Blvd., Boston, MA, 02125.

PMID: 29947151
DOI: 10.1002/rcm.8211

Abstract

Rational: The development of an automated platform for the positional analysis of triglycerides based on electrospray tandem mass spectrometry continues to be pursued. This work compares the positional sensitivities of the collisional-induced dissociation spectra for a representative set of YXY/YYX triglycerides using ammonium, silver, sodium and lithium as complexing agents.

Methods: A set of triglycerides were synthesized and analyzed by electrospray tandem mass spectrometry using an ion trap mass spectrometer. Using different salt additives, the product ion spectra of the corresponding parent ions for twelve systems of the form YXY/YYX, where Y and X represent C_16:0 , C_18:1(c-9), C_{18:2(cc-9,12)} and C_{20:4(cccc-5,8,11,14)} , were collected. The data was used to prepare two-point calibration plots for each of the twelve positional isomer systems using each of the four complexing agents.

Results: The positional sensitivities for all twelve positional isomer systems were robust for both the sodium and lithium TAG adducts. The CID data for both the sodium and lithium TAG adducts are much less sensitive to the degree of unsaturation and double bond position of the fatty acids constituents than the CID data for the ammonium adducts.

Conclusion: Using sodium or lithium TAG adducts may be advantageous for the development of an accurate predictive model for performing positional analysis of complex TAG mixtures based on electrospray tandem mass spectrometry. Ammonium adducts are likely complicated by the ability of the ammonium ion to provide extra stability to some parent ions through hydrogen bond-like interactions.