Ionic liquid matrix-based dispersive liquid-liquid microextraction for enhanced MALDI-MS analysis of phospholipids in soybean.

Ionic liquid matrix (ILM) is found to be a very versatile substance for analysis of broad range of organic molecules in matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) due to good solubility for a variety of analytes, formation of homogenous crystals and high vacuum stability of the matrix. In the present work, an ILM, cyno-4-hydroxycinnamic acid-butylamine (CHCAB) was employed in dispersive liquid-liquid microextraction (DLLME) as sample probe and matrix for extraction and ionization of phospholipids from food samples (soybean) prior to MALDI-MS analysis. With the employed technique, 8-125 fold improvement in signal intensity and limit of detection were achieved for the analysis of phospholipids. The best extraction efficiency of phospholipids in ILM-DLLME was obtained with 5min extraction time in presence 30mg/mL CHCAB and 1.2% NaCl using chloroform as an extracting solvent and methanol as a dispersing solvent. Further, the developed ILM-DLLME procedure has been successfully applied for the analysis of phospholipids in soybean samples in MALDI-MS.