A novel derivatization reagent for ultra-sensitive determination of free fatty acids in complex matrices by UHPLC-QQQ-MS

Plant oils are vital dietary sources of ω-3, ω-6, and ω-9 fatty acids, but their accurate quantification remains challenging due to their low abundance and complex matrix interference. Herein, we developed a novel derivatization method using 1-(2-diisopropylaminoethyl) piperazine (DPATP) coupled with ultra-high performance liquid chromatography-tandem triple quadrupole mass spectrometry (UHPLC-QQQ-MS/MS). This method offers the simultaneous analysis of 11 fatty acids with a remarkable 300-fold sensitivity enhancement, and limits of quantification as low as 0.4 fg. Comprehensive optimization revealed that liquid-liquid extraction (LLE) outperformed solid-phase extraction (SPE) in recovery efficiency. The derivatization reaction (30 °C for 10 min) was optimized to improve chromatographic resolution and ionization efficiency. Method validation confirmed good linearity, high precision, and acceptable accuracy. Minimal matrix effects and satisfactory recoveries further underscored the method's robustness. The established derivatization-UHPLC-QQQ-MS/MS approach was successfully applied to quantify FFAs in plant oils. This DPAPT-derivatization LC-MS platform is a powerful tool for ultra-sensitive FFA analysis, promising broad applicability in food science, lipidomics, clinical diagnostics, and environmental analysis.