Determination of Free Fatty Acids in Cheese by Means of Matrix Solid-Phase Dispersion Followed by Ultra-High Performance Liquid Chromatography and Tandem Mass Spectrometry Analysis

Cheese as milk derivate plays a key role in our diet due to their nutritional and functional properties; free fatty acids (FFAs) and especially conjugated linoleic acids (CLAs) represent important healthy components in a dairy matrix. In this study, with the aim to detect FFAs in dairy products, we have developed a fast and accurate analytical protocol based on a matrix solid-phase dispersion (MSPD) extraction followed by ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) analysis. The proposed method provides a rapid and selective sample pretreatment and a reliable instrumental analysis. The use of MSPD extraction with a suitable dispersing phase as C18, allowed the retention of triglycerides, which are the main cause of interference and matrix effect in this type of analysis and permits a selective elution of the FFAs. The whole method was validated demonstrating the feasibility of the proposed method: correlation coefficients greater than 0.99 were obtained for all analytes; matrix effects were minimized and recoveries ranged between 75 and 105%, with good reproducibility (≤ 12%).