Study Of Detecting Melamine And Cyanuric Acid In Dairy Products

With the improvement of people's living level, more and more attention was paied to the safety of food, so, the nicety detecting of contamination and residues of food is key to control the safety of food. Especially in September of 2008, most importance food safety event of'sanlu'happended, and lead many infants appear concretion in kidney. The effect to the society is huge.The paper aimed to systemly study factors influence nicety detecting of melamine in the method of (GB/T 22388-2008), the method of LC-MS/MS is widely used now, put out with The General Administration of Quality Supervision, Inspection and Quarantine of the Republic of China. Then, we try to quantify the factors and to increase the detecting nicety of melamine. The study has importmant meaning of detecting in food, especially in dairy products, and enrich the basic theory of analyse method.The main content of paper is as followed:(1) Determine the influence of factors (the concentration of salt and PH) in mobile phase to melamine's chromatogram performance with CR column and SCX column. Determine the mechanism of CR column preserving melamine.(2) Determine the relative standard deviation of peak area of melamine because of automatic sampler in HPLC and try to quantize the influence.(3) Determine the relative standard deviation of peak area of melamine in raw milk and dairy products with different SPE columns manufactured by different factories. Determine the relative standard deviation of peak area of melamine in different dairy products.(4) Establish a method detecting of cyanuric acid, determine the factors influence detecting of cyanuric acid and try to find out the cause of infants'concretion in kidney.Through above experiments, following facts were discovered:(1) The mechanism of preserving melamine with CR column①With SCX column, with the increase of the concentration of salt, the retention time of melamine becomes short, the symmetry of the peak of melamine becomes no good, sensitivity becomes good, peak width1/2 becomes narrow and the peak area diminish. With the increase of PH in mobile phase, the retention time of melamine becomes first long and then short, the symmetry of the peak of melamine becomes good, sensitivity becomes good, peak width1/2 becomes first wide and then narrow and the peak area diminish. When the PH of mobile phase is 3.0 and 2.5, the symmetry of the peak of melamine amend largely.②With SCX column, with the increase of the concentration of salt, the retention time of melamine becomes short, the symmetry of the peak of melamine becomes bad, sensitivity becomes bad, peak width1/2 becomes narrow and the peak area diminish, with the increase of adding HAC in mobile phase, the retention time of melamine becomes long, the symmetry of the peak of melamine becomes good, sensitivity becomes good, peak width1/2 becomes wide and the peak area augment.(2) The influence of automatic sampler in HPLC in detecting of melamine①In room temperature, the peak area change largely when sample volume is small and the concentration of melamine is low.②In 4℃, the trend of the change is same as above.(3) The influence of SPE column in detecting of melamine①Coefficient of recovery of melamine with SPE column of different factory is fluctuant, the maximal range is 12%.②Coefficient of recovery of melamine in different dairy products with SPE column get from W company is formula > pure milk > yoghourt > cheese >chocolate milk.③Coefficient of recovery of melamine in formula with SPE column get from W company in different batch is 89%,RSD% is 3.37%; coefficient of recovery of G is 84%,RSD% is 3.69%,coefficient of recovery of E is 74%,RSD% is5.18%.(4) The detecting of cyanuric acid and cyanuric acid with melamine①Establish a sample method detecting of cyanuric acid, with NH2 column, mobile phase is 10mM NH4AC and ACN, the ratio is 80:20,λis 200nm. This method's precision, coefficient of recovery, linearity is good and the detection limit is low.②When cyanuric acid and melamine coexist in formula, cyanuric acid first react with protein in formula, then react with melamine.③When the concentration of cyanuric acid in formula is 100mg/L, cyanuric acid can't be detected still.