Determination of Phospholipids in Antarctic Krill by Hydrophilic Interaction Ultra-high Performance Liquid Chromatography-Tandem Mass Spectrometry Using TiO₂/KCC-1 Solid Phase Extraction

Phosphatidylcholine (PC), phosphatidyl ethanolamine (PE), phosphatidylserine (PS), and phosphatidylinositol (PI) are the four major phospholipids in Antarctic krill. In this study, the composition of these phospholipids was analyzed by hydrophilic interaction ultra-high performance liquid chromatography-tandem mass spectrometry (HILIC-UPLC-MS/MS) after purification by solid-phase extraction (SPE) using titania-coated fibrous silica (TiO₂/KCC-1) nanoparticles, which had been prepared in our laboratory. The results showed that under the optimal conditions, 291 phospholipids including 75 PCs, 120 PEs, 54 PIs and 42 PSs were detected, which were nearly twice as many as those detected by a previously reported method. Phospholipids containing monounsaturated and polyunsaturated fatty acid chains accounted for 54.73% and 26.17% of the total phospholipids, respectively. PC (40:6) (41.63%), PE (36:0) (39.77%), PI (38:3) (80.05%), and PS (36:1) (81.62%) were found to be the most abundant in the four phospholipids. Multivariate statistical analysis showed significant differences in the types of phospholipids before and after SPE treatment. TiO₂/KCC-1 nanoparticles exhibited a significant enrichment capacity for phospholipids, especially PC (18:0/18:0), PE (16:0/18:1), and PI (16:0/18:2). The detection limit was 0.05 μg/g for PC, PE and PS, and 0.01 μg/g for PI. The relative standard deviations (RSDs) for the four major phospholipids were in the range of 0.89% to 5.05%, and the recoveries were 87%–112%. This method demonstrated high specificity, extraction efficiency, sensitivity, precision and accuracy. Therefore, it has broad application prospects for the extraction, purification, and analysis of phospholipids in biological samples.