The Study Of Melamine Detection Methods And Migration And Transformation In Soil-crop Systerm

Melamine （1,3,5-triazine-2,4,6-triamine, C3H6N6） is a triazine-basedindustrial chemical commonly used in the production ofmelamine-formaldehyde resin. In recent years, pet food, wheat flour, infantformula, egg and other protein-rich food commodities were found to becontaminated with melamine and its analogs. Melamine is frequentlyadded to crop fertilizer to increase its nitrogen content. It is a concern thatmelamine residues are absorbed, translocated and accumulated by crops,thus posted an unacceptable food safety issue. Melamine residues can befound in many consumer products throughout the world. Its potentialimpact to consumer health and safety is still not completely defined.Therefore, the development of sensitive and efficient methods formelamine residues in environmental and food samples is urgently needed.We used a combination of indoor analog pot experiment in the study,established the detection method of melamine in the fertilizer base onHPLC and LC-MS/MS, maked use of crop of paddy soil for the test soil,vegetables, wheat and potatoes for the test, adopted N¹⁵isotope tracermethod to carry out soil-crop system of melamine migration andtransformation mechanism principle, and researched the melamine wasteresidue resource utilization technology. The main findings are as follows: 1. The operation parameters for HPLC including: UV detectorwavelength of240nm, flow rate1.0mL/min, acetonitrile/heptane sodiumand citric acid buffer （15/85, v/v） as the mobile phase, under theseconditions, melamine in the range of0.5³0μg/mL has a superior linear,linear regression equation: Y=48822X+3396.7, R²=0.9999.2. The operation parameters for LC-MS/MS including: WCX column,without ion pair reagent in the mobile phase, flow matches ratio ofacetonitrile/10mmol ammonium acetate90/10（v/v）, mobile phase pH of4.00for melamine determination, retention time can be extended to4.08min, peak shape, symmetry. Under these conditions, melamine in the rangeof1⁵0ng/ml has a superiorlinear, linear regression equation: Y=99573.2X－10418.1, R²=0.9990.3. Ammonia solution in methanol as an extraction reagent formelamine in soil, ultrasound5min, melamine in the range of50⁸00μg/mL spiked an average recovery rate of82.6%to90.7%, and thecoefficient of variation of0.76%to2.78%. For vegetables we used1%trichloroacetic acid extraction kit, ultrasound5min,50mL extracted once,add a level within the range of0.2²0mg/kg, the recovery rate of71.2%to95.4%, the coefficient of variation of1.40%to5.19%; For potatoes weadd ed a level within the range of1.0⁵0mg/kg, the recovery rate of93.8%to107%coefficient of variation of2.12%to2.43%. The mechanicaloscillations was used in the extraction process of melmaine in fertilizer,ammonia/methanol/water （20/70/10, v/v/v） as the extraction reagent,15/85acetonitrile/heptane sulfonate-citric acid buffer as a constant volume fluid,the detection sensitivity was greatly improved. Under this method, weadded melamine in the concentration range of5⁵00mg/kg in fertilizers, the average recovery of95.1%to99.6%. The method was proved to beaccurate, reproducible, satisfy melamine analysis requirements.4. The degradation rate of melamine in will slower with increasingsoil concentrations of melamine increasing,20days later, the degradationcurve posed a tend of gentle, slow speed, residual time extending, itsdegradation dynamics met the Logistic equation.5. The isotope dilution method confirmed that vegetables can absorbmelamine in soil, and melamine can lead a inhibition for vegetables growth;and vegetables increased uptake of cyanuric add melamine in higherconcentration in the soil, the stronger growth inhibition. Potatoes’melamine absorption ability above vegetables’; and as to vegetables, itsroots uptake melamine higher than the stems and leaves.6. When the melamine content in soil was0²00mg/kg, appliednitrogen fertilizer to wheat, we find the impact of absorb melamine contentwas not significant, when the melamine content in soil higher than400mg/kg, applied nitrogen fertilizer to wheat, we find an obvious inhibit ofwheat for absorption of melamine. Catalysts A, B can be used to reduce theplants’ absorption of melamine.