Phospholipid analyses by MALDI-TOF/TOF mass spectrometry using 1,5-diaminonaphthalene as matrix

• DAN was applied as a matrix to identify phospholipids species using MALDI-TOF/TOF.
• DAN was superior and more efficient than DHB and 9AA in MALDI based lipidomics.
• DAN was used as MALDI matrix to identify PE and PG classes from G. stearothermophilus.

Phospholipids (PLs) are the major components of cellular membranes and play important biological roles. To effectively identify PL species and avoid chemical background interferences, 1,5-diaminonaphthalene (DAN) was introduced as a matrix in this study. A systematic evaluation of three established matrix substances, especially 2,5-dihydroxybenzoic acid (DHB) and 9-aminoacridine hemihydrate (9AA) as reference compounds, for phospholipid (PL) analysis was performed. Spectra of all analytes (phosphocholine (PC) in positive ion mode, the rest in negative ion mode) using DAN as the matrix showed only protonated/deprotonated analyte signals. Moreover, the spectra were totally devoid of any matrix related signals. In addition, ionization efficiency of PLs using DAN as matrix was evaluated, and improved signal intensities of analytes with low laser energy were produced, making DAN a versatile and sensitive reagent for PL analysis. DAN was also successfully applied to the PLs identification of Geobacillus stearothermophilus, in which phosphatidylethanolamine (PE) and phosphatidylglycerol (PG) were found to be the major classes. All the results indicate that DAN is a promising matrix for high-speed and effective lipidomics study by MALDI-TOF/TOF-MS.

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