Analysis Of Triazines In Milk By Cloud Point Extraction And High Performance Liquid Chromatography

The nutritional value of milk is extremely high. It can satisfy the nutrient demands ofchildren and the elderly, and strengthen the physique of human body. With the fastdevelopment of dairy industry and the continuous improvement of consumption level, milkconsumption per capita has greatly increased, so the requirements for the security of milkbecome much higher. Triazine pesticides are widely used for weeding in farmland. They canpollute the soil, water and crop, leading to endocrine-disrupting and carcinogenic effect.Silage maize straw is the main crude feed for raising cows in China, which cause the triazineresidues in milk. Therefore, providing milk that of high quality and safety is on the way.Cloud point extraction is a new pretreatment method which is environmental friendly. It hasa wide application area. Compared with conventional solvent extraction, this method has theadvantages of simple operation, less organic solvent consumption, and high extractionefficiency, which could well conform to the trends of modern analytical chemistry. In thispaper, we focused on researching the conditions of cloud point extraction and highperformance liquid chromatography for analysing triazine pesticides in milk. Finally we builtan ideal method, the main results were as follows:(1) The CPE pretreatment conditions for extracting triazine pesticides in milk were built.We optimized the conditions of de-emulsification and cloud point extraction in theexperiment. The best de-emulsification conditions were:40μL glacial acetic acid and0.90gNa2SO4, centrifugation at9917.355g (10000rpm),5°C,10min. The optimal cloud pointextraction conditions were:60g/L concentration of Triton X-100, the supernatant pH of5,equilibrated at60oC for30min. In order to validate the proposed method, three differentspiked levels (0.02,0.05,0.2μg/mL) with three replicates were carried out. The recoverieswere70.8-97.0%with relative standard deviations of1.03to5.85%, which demonstrated thatthe experimental results were accurate and precise.(2) Combined with high performance liquid chromatography-UV detector, we optimized chromatographic conditions. Reversed phase column used WondaSil C18(4.6mm×150mm,5μm), mobile phase were consist of acetonitrile (A) and water (B), detectionwavelength set at235nm, flow rate was1mL/min, and column temperature was40oC. Theprogram of binary high-pressure gradient elution set as:0-20min,30%A;21-31min,100%A;32min,30%A. Under the optimized chromatographic conditions, the four triazines in themilk could separate well, and no miscellaneous peak interference; each pesticide standards inthe range of0.05-2μg/mL had a good linear relationship, and the LODs were6.79-11.19μg/kg, lower than the limit requirements of the U.S. Environmental Protection Agency andthe European Commission.Using the method of cloud point extraction and high performance liquid chromatographyto analyze triazine pesticides in milk has the advantages of simple operation, environmentallyfriendly and practical. It can also be used for large sample level analyzing, meeting theanalysis requirements of pesticide residues.