微波消解-电感耦合等离子体质谱法测定奶粉中的铬

Determination of Chromium in Milk Powder by ICP-MS combined with Microwave Digestion

本方法采用微波高压消化仪消解奶粉样品,以电感耦合等离子体质谱法（ICP-MS）测定奶粉中的铬元素含量,同时采用干灰化-原子吸收石墨炉法（国标法）测定样品,与本方法进行比较。实验表明样品浓度、积分时间与响应值呈正相关,当样品中铬的浓度大于10μg/L时,应采用0.1s的积分时间;当铬的浓度小于10μg/L时,应采用高于2.0s的积分时间。实验结果显示该方法与国标法的测定结果相吻合,测得相对标准偏差为0.92%-4.21%,回收率为95.6%-102.2%,在1.0-500μg/L范围内呈良好的线性关系（r=0.9999）。本方法具有操作简单、快速、灵敏度高、抗离子干扰能力强的优点,完全适用于快速准确测定奶粉中的铬元素含量。

A new method was established to determine chromium content in milk powder by ICP-MS after microwave digestion. The chromium content was also determined with National Standard method （Graphite Furnace Atomic Absorption Spectrometry）. Positive correlations between sample concentration/integration time with the response value were found. When Chromium concentration in the sample was 10 μg/L, integration time should be selected as 0.1 s. On the contrary, integration time should be 2.0 s when chromium concentration was 10 μg/L. The results were in accordance with that obtained by national standard method. Besides, the average recovery and RSD of the new method were 0.92%-4.21%, and 95.6%-102.2%, respectively under selected condition, within the linear range of Chromium of 1.0-500 μg/L, RSD of the method （r=0.9999）. The method was sensitive and accurate, which could be used for the determination of Chromium in milk powder.