One-Step Labeling and Purification: Accelerating FAHFA Detection in Vegetable Oils via Chemoselective Probe-Assisted LC–MS

Fatty acid esters of hydroxy fatty acids (FAHFAs) are emerging bioactive lipids in edible oils, but their trace-level presence and matrix complexity hinder accurate analysis. Here, we designed a novel chemoselective probe piperazine-modified silica (SiO2-PP) that specifically captures FAHFAs while removing almost totally triglycerides in a one-step labeling reaction. The probe enabled single-batch sample pretreatment within 30 min, integrating capture, purification, and signal amplification. Coupled with liquid chromatography–mass spectrometry, the method achieved high sensitivity (LOD: 0.0039–0.033 ng/mL) and enabled quantification of 47 FAHFA isomers in 47 vegetable oil samples, with concentrations ranging from 0.56 to 1.76 × 104 ng/g. Five dominant isomers (e.g., 10-OAHSA) were identified, with olive and peanut oils exhibiting the highest FAHFA concentrations. This approach provides a promising platform for high-throughput functional lipid profiling, effectively overcoming the inefficiencies of traditional methods while significantly enhancing the assessment of vegetable oil quality.