Determination Of Phenolic Antioxidants In Food By High Performance Liquid Chromatography

Many foods which are rich in unsaturated fatty acids, are liable to lipid peroxidation. Eventually, the quality of foods will deteriorate. Vitamins and pigments in foods can be destroyed (thereby reducing their nutritional values), and foods may became malodorous and off-flavours.So, free radicals from oxidation are dangerous to human being. Therefore, prevention of liqid peroxidation has become an important issue. As adding an appropriate amount of food antioxidants, can effectively prevent the unsaturated fatty acids by air oxidation, and prolong the shelf life of foods; it is necessary to add appropriate amount of antioxidants to maintain nature characters and nutritional values of foods, however excessive adding anti-oxidants in food is also harmful to humans.In this paper, detection methods for7kinds of phenolic antioxidants in food have been investigated using HPLC and UPLC-MS/MS technologys, and the relevant contents were as follows:1. A mothod for determitation of7kinds of phenolic antioxidants in foods were established by HPLC technology with a diode array detector. Detection was performed on a ZORBAX Eclipse XDB-C18column by diode array detector at280nm with a gradient system of methanol and water (containing0.1%acetic acid). In the blank matrix experiments, these antioxidants showed good linear relation (R2>0.999), and the detection limits (LOD) and limits of quantification (LOQ) were respectively from0.2to0.4mg/kg and0.7to1.0mg/kg. The RSD of seven antioxidants were all less than3.0%for12times repeated experiments. Standard addition tests of4matrix samples (vegetable oil, photo chips, puffed food, and roasted seeds and nuts food) were repeated for6times by the same mothod. The results showed that the average recoveries of phenolic antioxidants ranged from87.3%to103.2%, and relative standard deviations were less than10%. Furthermore, the method also exbihits good generality in real detection work.2. A mothod for determitation of7kinds of phenolic antioxidants were established by mass spectrometric analysis technology. In the UPLC-MS/MS experiments,40μg/L standard solution was in a flow jnjection, and two ion modes, positive and negative on the target parent ion scanning were compared to select a proper ion mode. For the selected target ions, a multiple reaction monitoring method was established through optimization of MS systems (including capillary voltage, cone voltage, source temperature, desolvation temperature, removal of solvent flow, collision energy, and so on), and determinion of two product ions possessing high signals. After analysis of the Collision Induced Dissociation of seven phenolic antioxidants, we guessed the possible fragmentation pathways of phenolic antioxidants.3. A method using a Waters ACQUITY UPLC BEH C18column with a gradient system of methanol and water (containing0.1%formic acid), used to analysis3kinds of phenolic antioxidants was established by UPLC-MS/MS technology. The LOQ in blank matrix were from0.015to0.030μg/kg with RSD<3.0%(n=12). Standard addition test of vegetable oil sample was repeated for6times using the same mothod. The average recoveries of phenolic antioxidants ranged from92.5%to101.5%, and relative standard deviations were less than6.8%.