电感耦合等离子体质谱法测定鲜奶、酸奶和奶粉中稀土元素

建立了电感耦合等离子体质谱法(ICP-MS)测定乳及乳制品中16种稀土元素的方法。采用微波消解前处理技术消解样品,优化了仪器工作参数,选择¹⁰³Rh、¹¹⁵In和²⁰⁹Bi元素作为内标,校正基体干扰。结果表明,16种稀土元素质量浓度在0.2~5 ng/mL范围内线性关系良好,线性相关系数r≥0.9995,检出限在0.03~0.52 μg/kg之间,平均回收率在92.3%~109.0%之间,相对标准偏差(RSD)为2.21%~5.36%。采用该方法测定国家标准物质柑橘叶(GBW10014),其测定值均在标示值范围内。对市售鲜奶、酸奶和奶粉中稀土元素进行检测,结果显示,3类乳品中均检出稀土元素,含量为0.04~19.3 μg/kg。该方法具有快速、准确、操作简便,能够满足鲜奶、酸奶和奶粉中稀土元素的测定。

Determination of Rare Earth Elements in Fresh Milk,Yogurt and Milk Powder by Inductively Coupled Plasma Mass Spectrometry

A method for determination of 16 rare earth elements in milk and dairy products was developed by inductively coupled plasma mass spectrometry(ICP-MS). Samples were digested by the pretreatment technique of microwave digestion,and the operating parameters of the instrument were optimized,then 103Rh,115 In and 209Bi were selected as internal standard elements to correct matrix interference. The results showed that the mass concentration range of 0.2~5 ng/mL for 16 rare earth elements had good linearity with r≥0.9995,the detection limits were 0.03~0.52 μg/kg,the average recoveries were between 92.3% and 109.0%,and the relative standard deviations(RSDs)were 2.21%~5.36%. The method was applied to determine the national standard reference material of citrus leaf(GBW10014),and the determined values were all in the range of the recommended values. The rare earth elements were detected in fresh milk,yogurt and milk powder in the market.The results showed that the contents of rare earth elements were 0.04~19.3 μg/kg in all three kinds of dariy products.The method was rapid,accurate,easy and convenient to operation,and could be used for the determination of rare earth elements in fresh milk,yogurt and milk powder.