微波消解法提取玉米中铅镉含量的条件优化

Optimization of extraction conditions of lead and cadmium content in corn by microwave digestion

目的优化微波消解法提取玉米中重金属铅镉的消解条件,并采取石墨炉原子吸收法测定其中的铅镉含量。方法以硝酸与过氧化氢比值及微波消解仪第3个阶段的温度、升温时间、保持时间为4个研究因素,对玉米实验材料和标准样品进行微波消解,以回收率为评价指标,通过正交试验确定在检测玉米中铅镉含量时微波消解的最佳条件。结果在处理玉米样品时,微波消解的最佳条件是硝酸和过氧化氢用量比为6:2(V:V),微波消解第3阶段温度为200℃,升温时间为8 min,保持时间为12 min。经方法学验证,发现优化方法的相对标准偏差为1.05%~1.21%,回收率为95.1%~96.8%。结论此优化方法处理玉米样品节省时间,消解完全,同时能够提高检测结果的准确度和精密度,适合大批量玉米样品中铅镉的检测。

Objective To optimize the digestion conditions for the extraction of lead and cadmium in corn by microwave digestion and to determine the content of lead and cadmium in graphite furnace atomic absorption.Methods The ratio of nitric acid to hydrogen peroxide and the temperature,heating time and holding time in the third stage of microwave digestion instrument were used as four factors to conduct microwave digestion on experimental materials and standard samples of corn.Based on the evaluation index of recovery,the optimal conditions for microwave digestion when determining the content of lead and cadmium in corn were determined by orthogonal experiments.Results When processing corn samples,the optimal conditions for microwave digestion were a ratio of nitric acid and hydrogen peroxide of 6:2(V:V),the temperature of the third stage of microwave digestion was 200℃,the heating time was 8 minutes,and the holding time was 12 min.After methodological verification,the relative standard deviation of the optimized method was 1.05%-1.21%,and the recovery rate was95.1%-96.8%.Conclusion This optimization method can save time and dissolve corn samples completely,and improve the accuracy and precision of test results.It is suitable for the detection of lead and cadmium in large quantities of corn samples.