HPLC-DAD Method For The False-positive Determination In Food Additives

Food is the fundamental requirement for human survival; consequently, food security issue is significant and closely related to people’s health. Howerever, the excess usage and even abuse food additives occur frequently, thus making it particularly important to find effective methods to realize qualitative and quantitative detection of food additives. For years, the prevalence of such issues as false-positive, background interference has haunted analysts. As a result, this dissertation established new detection methods to sense the content of melamine, sodium cyclamate, benzoic acid and sorbic acid among food based on high performance chromatography and diode array detector, and satisfactory results have been got.The determination of melamine in dairy products by high performance liquid chromatography-diode array detector was realized. By one-factor analysis, the optimum extraction condition of melamine in dairy products was investigated. The sample, using trichloroacetic acid-lead acetate as the extracting agent was determined by high-performance liquid chromatography-diode array detector by external standard method. The spectrogram was then acquired with DAD detector and supplemented by mass spectrum to gain qualitative results. Under the selected chromatographic conditions, the false-positive problem in melamine examination process is solved effectively. The standard curve is linear in the range of1.0～100μg/mL, the regression equation was y=44.35x-16.15, the correlation coefficient is0.9999, the detection limit is0.2mg/kg, the recovery is91.2%～97.2%, and the RSD is2.08%-3.13%.An HPLC analysis method was established for the determination of sodium cyclamate in rice wine, soy sauce and beverages. Under acidic condition, the sodium cyclamate was derivatized to N, N-dichloro-cyclohexylamine. Then the optimal conditions of derivative reaction were investigated. The results show that the linear correlation is excellent in the range of2～100μg/mL and the regression equation is y=1.26x+1.36, the correlation coefficient is0.999. The detection limit is0.63mg/kg, the recovery is94.8%to105.8%, the RSD is2.5%-5.1%. The method is confirmed to be accurate, efficient, reproducible, and able to meet the concrete requirements of sodium cyclamate’s determination.An analytical method of HPLC-DAD for benzoic acid and sorbic acid was established. Under the selected chromatographic conditions, the standard curve shows good linearity in the range of1.0-100μg/mL, the regression equation of benzoic acid is y=45.96x-4.898(R2=0.999, n=5); the regression equation of sorbic acid is y=72.89x-30.81(R2=0.999, n=5). The detection limit of benzoic acid is0.15mg/kg and the detection limit of sorbic acid is0.18 mg/kg. When samples were added in the spiked lever, the average recovery is between86.7～103.5%, and RSD is1.9～4.4%.