微分电位溶出伏安法同时测定甘草中痕量铅和镉

SIMULTANEOUS DETERMINATION OF TRACE LEAD AND CADMIUM IN LICORICE BY DIFFERENTIAL POTENTIOMETRIC STRIPPING VOLTAMMETRY

建立了在NH4OAc HOAc介质中,用微分电位溶出伏安法测定中药甘草中痕量铅和镉的方法,利用该法对中药甘草煎煮前后及其煎液中铅和镉的含量进行测定。试验表明,镉和铅分别在-0.66V(vs.SCE)和-0.47V(vs.SCE)电位处形成两个灵敏的二次微分溶出峰;铅在0～0.8mg·L-1,镉在0～0.4mg·L-1范围,峰电流与浓度呈良好的线性关系;铅和镉检出限分别为0.15和0.1μg·L-1,相对标准偏差≤1.39%;铅和镉加标回收率在94%～103%之间。结果表明,该甘草样品中铅和镉含量均低于国家安全标准,甘草煎煮液中铅的浸出率较高,镉的浸出率则较低,方法也适用于其它类似中药。

A new method of differential potentiometric stripping voltammetry was established for the determination of trace lead and cadmium in licorice. Determination was carried out in medium of NH 4OAc HOAc buffer, after digestion. Pb 2+ and Cd 2+ in the decocted solution of licorice have also been determined. Experimental results showed that the method has a good linearity of peak current vs concentration in the range of 0~0.8 mg·L -1 for Pb 2+ and 0~0.4 mg·L -1 for Cd 2+ with recoveries of 94%~103%, and the detection limits of Pb 2+ , Cd 2+ were 0.15 μg·L -1 and 0.1 μg·L -1 , respectively, with RSD≤1.39 %. The experiment findings has prored that the content of Pb and Cd was all lower than the National Standard of Safety, with Pb decocted a little higher than that of Cd in the decocted solution of licorice, the method could meet the requirements of dissolved lead and cadmium measurement of licorice either for routine licorice analysis and also suitable for other Chinese traditional herbs.