Nitrocellulose Film Substrate Minimizes Fragmentation in Matrix-Assisted Laser Desorption Ionization Time-of-Flight Mass Spectrometry Analysis of Triacylglycerols

The potential of matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry (MS) for the analysis of intact triacylglycerols (TAGs) is generally limited by the extensive in-source prompt fragmentation. The sequential deposition of matrix and TAGs over the stainless steel target precoated with a thin layer of nitrocellulose (NC) drastically reduced fragmentation in the MALDI-TOF MS profiling of oils and fats. The NC MALDI-TOF MS profiles of native and thermally stressed virgin olive oil and butter are reported as case studies, along with test analyses of a standard mixture of mono-, di-, and triacylglycerols. Mass spectra were almost completely devoid of both fragment and matrix ion signals, thus disclosing relevant information, especially in the low molecular mass range. The detection of several partial acylglycerols of low abundance and minor TAGs that are barely observed with other techniques also provided evidence for an increased dynamic range of NC MALDI-TOF MS that was due to the minimization of suppressive effects. The NC film substrate also improved the shot-to-shot and sample-to-sample reproducibility of the ion production through the exhibition of a more homogeneous matrix/analyte cocrystallization, thus enabling MALDI-based measurements to a consistent quantification of TAGs.