Improving Quantitative Accuracy in Nontargeted Lipidomics by Evaluating Adduct Formation.

Area of Science:

• Analytical Chemistry
• Lipidomics
• Mass Spectrometry

Background:

• Accurate quantification of endogenous lipids is essential for large-scale lipidomic studies.
• Lipids form various adducts during liquid chromatography-electrospray ionization-mass spectrometry, complicating quantification.
• Adduct formation mechanisms and conditions are not fully understood.

Purpose of the Study:

• To investigate adduct formation in diacylglycerols (DAGs) across diverse biological matrices.
• To evaluate the impact of adduct variability on lipid quantification accuracy.
• To determine optimal strategies for accurate DAG quantification in mass spectrometry.

Main Methods:

• Analysis of 48 diacylglycerol (DAG) species in 2366 mouse samples from eight different tissues.
• Examination of adduct ion species ([M + NH4]+, [M + Na]+, [M + K]+) in MS1 precursor ion spectra.
• Use of deuterated internal DAG standards to assess quantification accuracy with different adducts.

Main Results:

• No single adduct ion species consistently represented over 60% of the total abundance for DAGs.
• Significant variability in adduct ratios was observed even within the same biological matrix.
• Quantification errors reached up to 70% when using only one adduct ion.
• Combining [M + NH4]+ and [M + Na]+ adducts improved accuracy to within 5%.

Conclusions:

• Adduct variability significantly impacts the accuracy of lipid quantification in mass spectrometry.
• A comprehensive approach considering multiple adducts, particularly [M + NH4]+ and [M + Na]+, is crucial for precise DAG quantification.
• Standardized methods accounting for adduct formation are needed for reproducible lipidomic analyses.