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建立了高效液相色谱仪(HPLC)与电感耦合等离子质谱仪(ICP-MS)联用同时测定乳制品中的三价铬和六价铬的方法。样品在EDTA缓冲液中煮沸,冷却后在离心机中以8000 r/min离心10 min沉降蛋白质,取清液用0.45μm滤膜过滤,就完成了三价铬和六价铬的同时提取。以NH4NO3为流动相(pH=7.0~7.2),流速为0.6 mL/min,使用HPLC-ICP-MS仅需4 min就完成了提取液中三价铬和六价铬的分离和测定。本文着重分析了各种前处理条件对测定结果的影响。EDTA加入量要过量以消除钙、镁等元素的影响;煮沸能显著加快EDTA与三价铬的络合速度,但时间不能过长,以2~3 min为宜;pH值在7.0~7.2时两种形态的铬回收率高,分离效果好。实验表明,三价铬和六价铬的线性范围在0.2~20μg/L,相关系数均大于0.9995,检出限分别为0.034μg/L和0.066μg/L。本方法操作简单,灵敏度高,准确性和精密度好。
A method for the simultaneous determination of trivalent chromium and hexavalent chromium in dairy products by high performance liquid chromatography (HPLC) and inductively coupled plasma mass spectrometry (ICP-MS) was established. The sample was boiled in EDTA buffer, cooled and centrifuged at 8000 r / min for 10 min to sediment the protein. The supernatant was filtered through a 0.45 μm filter to complete the simultaneous extraction of trivalent chromium and hexavalent chromium. The separation and determination of trivalent chromium and hexavalent chromium in the extract were performed with NH4NO3 as the mobile phase (pH = 7.0-7.2) at a flow rate of 0.6 mL / min in only 4 min using HPLC-ICP-MS. This article focuses on the analysis of the various pre-treatment conditions on the determination of the impact. The amount of EDTA to be excessive to eliminate the impact of calcium, magnesium and other elements; Boil can significantly speed up the complexation rate of EDTA and trivalent chromium, but the time can not be too long, 2 ~ 3 min is appropriate; pH value of 7.0 ~ 7.2 Both forms of chromium recovery rate, good separation. The experimental results show that the linear range of trivalent chromium and hexavalent chromium is 0.2 ~ 20μg / L, the correlation coefficient is greater than 0.9995, the detection limits are 0.034μg / L and 0.066μg / L respectively. The method is simple, high sensitivity, accuracy and precision.