Accurate and precise determination of free fatty acid (FFA) contents is essential for quality control and assurance in food production. Herein, a mass spectrometric study was performed to develop a sample preparation protocol that can minimize exogenous FFA contamination during the quantification of FFA in food. The quantities of exogenous FFAs were measured using various combinations of seven pretreatment methods for a sample tube, three extraction methods, and four types of sample tubes. Methanol washing could effectively reduce exogenous palmitic acid (PA) and stearic acid (SA) by 73 and 64%, respectively, in contrast to furnace baking resulting in a decrease in the amount of PA and SA contaminants by 50 and 37%, respectively. A lower amount of FFA contaminants was extracted from glass tubes during comparative analysis of the four different sample tubes studied. A combination of a methanol-washed glass tube and chloroform extraction solvent was determined to be the optimal method for minimizing the error in FFA quantification. The optimized sample preparation protocol used for FFA quantification can lower the amount of foreign palmitic acid and stearic acid to the sub-nanomolar level in the analysis of FFAs in skimmed milk.

The occurrence of pharmaceuticals in the aquatic environment has been increasing steadily owing to the increasing use of pharmaceuticals in our daily life. This results in increasing challenges of environmental health risk as pharmaceuticals in the surface water can be accumulated and transformed in aquatic organisms. The purpose of this study was to predict the bioconcentration and biotransformation of several pharmaceuticals in Japanese medaka (Oryzias latipes) using a 96 h exposure test. Based on an investigation of the most frequently detected pharmaceuticals in the surface waters in South Korea, 11 target compounds were selected including atenolol, caffeine, carbamazepine, diclofenac, fluoxetine, irbesartan, losartan, mefenamic acid, metoprolol, naproxen, and venlafaxine. A bioconcentration factor of 1.9, 31.3, and 10.7 was expected in fish owing to the accumulation of carbamazepine, fluoxetine, and mefenamic acid, respectively. A total of 12 biotransformation products (BTPs) were tentatively identified via oxidation, hydroxylation, dealkylation, and demethylation reactions. In summary, it is expected that these BTPs represented by molecular structures derived from their parent compounds can be utilized to evaluate the change in toxicity of BTPs compared to that of the parent compounds.