Abstract: 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, 38.59 μg/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.

Key words: ion-selective electrode, microwave digestion, a microamount of wolfberry, direct reading method