高效液相色谱内标法测定奶粉中三聚氰胺

Determination of melamine in milk powder by HPLC internal standard method

以双氰胺为内标物，采用高效液相色谱内标法测定奶粉中三聚氰胺的含量，通过对色谱条件的优化，最后确立了有效的检测方法。样品经20mL50℃热水，0．5g无水硫酸镁，10mL乙腈提取后，采用Nova—PakC18色谱柱（3．9mm×15mm×5μm）分离，以0．01mol／L乙酸铵：乙腈=90：10（V：V）作为流动相，218nm为检测波长。结果表明，双氰胺在该条件下能够与三聚氰胺完全分离，可以作为测定三聚氰胺的内标物。在0．500～1．500mg／kg的添加范围内，三聚氰胺的回收率为98．2％～100．5％。精密度实验结果相对标准偏差为0．44％。所测定奶粉样品中三聚氰胺为0．223mg／kg。此法处理样品处理简便易行，回收率、准确度高，分析速度快，具有良好的重复性和再现性，适于测定奶粉中的三聚氰胺。

With dicyandiamide as internal standard, the content of melamine in milk powder was determined by HPLC internal standard method. The effective detection method was finally established by optimizing chromatographic conditions. Sample was extracted by 50 % hot water 20 ml, anhydrous magnesium sulfate 0.5 g and methyl cyanide 10 ml, separated by Nova-Pak C18 chromatographic column （3.9mm×15mm×5μm）, with 0.01 mol/L ammonium acetate ： acetonitrile = 90：10 （V：V） as mobile phase, 218 nm as detection wavelength. The results showed that the dicyandi- amide was completely separated with melamine, and it can be used as the internal standard determination of melamine. Within the limits of adding 0.500-1.500 mg/kg, the recovery was 98.2%-100.5%, the relative standard deviation of precision results was 0.44%. The determination of melamine in milk powder samples was 0.223 mg/kg. The method was easy, simple, with high recovery and accuracy, fast analysis speed, with good repeatability and reproducibility. It was suitable for determination of melamine in milk powder.