基于QuEChERS前处理技术和弱阳离子交换色谱的牛奶和奶粉中三聚氰胺的快速检测方法

应用QuEChERS前处理技术,并结合弱阳离子交换色谱,建立了牛奶和奶粉中三聚氰胺的快速检测方法。样品使用医用酒精(乙醇含量75%)和一种新型脂肪吸附(LAS)材料超声振荡处理,在沉淀(吸附)蛋白质和脂肪的同时提取三聚氰胺,然后经8000 r/min离心,上清液过膜直接分析。色谱分析在弱阳离子交换色谱柱(WCX)上进行,采用2 mmol/L pH为3.8的磷酸二氢钾水溶液为流动相,在5 min内实现分离分析。结果表明,该方法在0.02～20 mg/L内线性相关系数大于0.9999。在1～50 mg/kg添加浓度范围内,牛奶的平均回收率为98.9%～105.2%,相对标准偏差(RSD)为0.9%～3.4%;奶粉的平均回收率为86.4%～102.9%, RSD为1.5%～6.7%。本方法的检出限为0.05 mg/kg(牛奶)和0.1 mg/kg(奶粉)。整个分析检测过程没有使用有毒有害有机溶剂,是一种绿色的分析方法。

Rapid analysis of melamine in milk and milk powder using QuEChERS approach coupled with weak cation exchange chromatography

A simple, rapid method for the determination of melamine in milk and milk powder was developed using QuEChERS approach coupled with weak cation exchange chromatography (WCX). The samples were extracted and cleaned-up by medicinal alcohol and lipid adsorbent (LAS) simultaneously, then centrifuged and filtered for high performance liquid chromatographic (HPLC) analysis. The separation was performed on a WCX column (150 mm x 4.6 mm, 5 microm) with 2 mmol/L KH2 PO4 (pH 3.8) as mobile phase. The flow rate was 1.5 mL/min and the detection wavelength was 208 nm. The injection volume was 20 microL and the column temperature was 30 degrees C. Under the optimized conditions, good linearity was obtained in the range of 0.02-20 mg/L with a correlation coefficient (r2) of 0.999 9. For samples spiked with melamine standard in the range of 1-50 mg/kg, the average recoveries of standard in the milk and milk powder were 98.9%-105.2% and 86.4%-102.9%, respectively. The relative standard deviations were 0.9%-3.4% and 1.5%-6.7%, respectively. The limits of detection (LOD, S/N > or = 3) were 0.05 mg/kg (milk) and 0.1 mg/kg (milk powder). The present method is green due to not use of the toxic organic solvents.