A Simple LC–MS method for the Determination of Free Fatty Acids in Coffee Beans and Cow Milk

The profiling of free fatty acids (FFAs) of coffee beans and cow milk is important for assessing their safety and quality. In this study, a liquid chromatography-single quadrupole mass spectrometry (LC–MS) method without derivatization was developed for the quantification of short- to very long-chain FFAs in coffee beans and cow milk. Using a mixture of methanol and 5 mmol L−1 ammonium acetate (95:5, v/v) with an octadecyl silyl group-bonded column (3.0 × 150 mm, 3 μm), 23 FFAs were separated and detected within 15 min. With the application of this method, a total of 17 FFAs in coffee beans and 15 FFAs in cow milk were determined. The coefficient of determination (R2) of the standard addition calibration curves obtained from coffee beans and cow milk were not less than 0.99. The reproducibility of each spiked concentration in the standard addition calibration curves showed relative standard deviations (RSDR, %) of less than 29.2%. The amounts of FFAs in coffee beans and cow milk ranged from 0.01 to 136.6 mg 100 g−1 and 0.1 to 35.1 μg mL−1, respectively. The FFA levels obtained by the proposed method showed comparable results to those reported in previous studies. Thus, the present study offers an additional methodological option with simple functionality and cost efficiency for food analysts to determine FFAs in coffee beans and cow milk.