Study on Differential Pulse Anodic Stripping Voltammetry Method for Simultaneous Determination of Trace amount of Zn, Cd, Pb, Cu in some Cough Syrups in Vietnam

The optimal measurement parameters of differential pulse anodic stripping voltammetry method (DP-ASV) to simultaneously determine the trace amount of the four elements Zn, Cd, Pb, Cu have been studied, including the sweep rate, pulse amplitude, drop size of mercury, initial purge, equilibration time. The analytical procedure was applied to determine Zn, Cd, Pb, Cu in 12 cough syrup samples in Viet Nam, including 6 functional food samples and 6 medicinal samples. The quantitative echnique used was standard addition and the applicability of quantitative elements in self - made samples was studied. Cough syrup analysis samples were digested using the wet ashing method in microwave oven. Research results show that there are no regular differences in elements content between medicinal cough syrup samples and functional food samples, except for functional food samples TP08 which has Pb content and the syrup medicine sample TH03 which has Cu content many times higher than other types. However, the content of the studied elements is within the allowable limits according to curent regulations (QCVN 8-2:2011/BYT; 46/2007/QĐ-BYT, WHO). The method has low detection limits and limit of quantification with ppb level, the relative standard deviations (% RSD) of repeated measurements are less than 3%, and recovery reflects the accuracy of the analytical method for elements ranging from 61.0 % to 87.5 %, which meets AOAC requirements for trace.