郑州市枸杞中铅含量的直读法测定及分布特性

Determination and Distribution Analysis of Lead Content in Different Organs of Wolfberry in Zhengzhou Suburb by Direction Reading Method

为建立一种快速测定食品中微量铅的新方法,以郑州市区的枸杞为材料,用微波压力消解技术快速处理样品,用铅离子选择性电极测定枸杞果、叶、茎中的铅含量并对其分布规律进行研究。结果表明:枸杞铅含量为果中68.86μg/g、叶中38.59μg/g、茎中31.33μg/g,加标回收率为94.6%～103.2%,相对标准偏差为0.9%～1.7%(n=11),铅的最低检出限为0.0103mg/L,测定的线性范围为0.105～204.7mg/L,相关系数为0.9990,电极斜率为27.367。该方法具有直观、简便、灵敏、准确、适于现场进行快速测定的显著优点。

A novel quick method to determine lead content in foods was proposed by direct reading on an ionic analyzer equipped with a lead-selective electrode following pressurized microwave digestion of samples.The lead contents of wolfberry fruits, leaves and stems from the same cluster in Zhengzhou suburb as determined by the method were 68.86,38.59μg/g and 31.33 μg/g,respectively.The average recoveries for lead in spiked wolfberry fruits,leaves and stems were between 94.6%and 103.2%,with relative standard deviation（RSD）of 0.9%to 1.7%（n=11）.The limit of detection for lead was 0.0103 mg/L.The calibration curve of the method was linear over the range of 0.105 to 204.7 mg/L,with a correlation coefficient of 0.9990.The electrode slope obtained was 27.367.This method proved to have the advantages of directness,simplicity,high sensitivity and accuracy and suitability of rapid on-the-spot determination.