Evaluation of carbonyl species in fish oil: An improved LC–MS/MS method

Fish oil, a common source of omega-3 fatty acids, can be easily oxidized to generate carbonyl species, thus, the measurement of these compounds in fish oil are significant for food safety. Here, a comprehensive and sensitive method to quantify forty-four carbonyl species including toxic substances such as acrolein, glyoxal, methylglyoxal and trans-4-hydroxy-2-hexenal in fish oil has been developed and validated. The samples were derivatized with 2,4-dinitrophenylhydrazine, cleaned using C18 solid phase extraction, and analyzed by liquid chromatography coupled with tandem mass spectrometry. The calibration curves represented satisfactory linearity (r² > 0.998) and the quality control samples showed favorable precisions within an acceptable range (RSD < 10%). The accuracies ranged from 96 to 109%. The detection and quantification limits ranged from 1.5 to 30 ng/mL and 5–90 ng/mL, respectively. The method was successfully applied to determine carbonyl species in ten fish oil products. The proposed method is suitable for high throughput analysis of carbonyl species in fish oil.