微波炉高压罐消化法在食品元素分析中的应用

APPLICATION OF PTFE CLOSED-VESSEL MICROWAVE OVEN DIGESTION METHOD FOR ANALYSIS OF ELEMENTS IN FOOD

本文介绍了利用自制聚四氟乙烯高压罐微波高压消化食物样品,扫描电感耦合等离子体发射光谱法测定微量元素的实验方法。讨论了不同的混合酸、不同的消化时间等因素对食物样品的消化影响。称取80℃干燥过4小时的0.2g样品置于聚四氟乙烯高压罐内,加3ml混合酸,拧紧高压罐盖后将其放置于微波炉腔内的聚四氟乙烯转盘上消化3分钟。消化完毕后,将高压罐放进-25℃的医用低温冰箱内冷却10分钟。然后用亚沸蒸馏水定容至25ml,测定国内外三种食品标准物质中的常量元素Ca、Mg及微量元素Fe、Mn、Cu、Zn含量。方法的元素回收率为90.0～103.8％,变异系数为0.6～6.3％,结果满意。

A method for the digestion of food samples by using PTFE closed-vessel microwave oven has been established. Six elements in the solution were determined by ICP-AES. The effects of various acid mixtures and digestion time were studied. 0.2 g of powdered samples dried for four hours at 80℃ were weighed and put into 50 ml PTFE digestion vessels. 2 ml of 70% HNO3 and 1 ml of 30% H2O2 were added to each sample digestion vessel. The screw caps were tightened and placed on the microwave oven PTFE turntable for 3 min at 100% full power (500W). When digestion was finished, the vessels were cooled for 10 min in a medical refrigerator at -25℃. The sample solutions were diluted to 25 ml with subboiling water. The contents of Ca, Mg, Mn, Fe, Zn and Cu in 3 standard reference materials were determined by ICP-AES. The results are in good agreement with certified values.