STUDY ON THE SIMULTANEOUS DETERMINATION OF ULTRA TRACE LEVELS OF COPPER AND CADIMIUM IN TEA SAMPLES BY STRIPPING VOLTAMMETRY, USING MODIFIED CARBON NANOTUBES PASTE ELECTRODE

Abstract

    Mecury film electrode prepared in situ on the support of nano-silver and carbon nanotubes(MFE/nanoAg-C) was used for the simultaneous determination of sub-ppb levels of copper(II) and cadmium (II) by differential pulse - anodic stripping voltammetry (DP-ASV) in thesolution of 0.1 M acetate buffer (pH = 4.5). Conditions for fabrication of the electrode werefound: the carbon nanotubes paste/nano silver/tricresyl phosphate binding oil mass ratio(mC:mAg:mTCP) of 5:1:4; the mixture dried at suitable temperatures and then packed into oneend of a Teflon electrode probe. Influence of supporting electrolytes and interferents such asmetal ions on copper and cadmium stripping responstripes was surveyed. Under suitableconditions, the method gained high reproducibility of the metal stripping peak curent: RSD 0.8% (n = 9) for copper and 1.1% (n = 9) for cadmium, and low limit of detection (3): 0.2 ppbfor each metal at a deposition potential of - 1200 mV for a deposition time of 60 s - 120 s. TheDP-ASV procedure using MFE/nanoAg-C was successfully applied to simultaneousdetermination of copper and cadmium in tea samples in Binh Dinh province.

Keywords: Electrodes modified MFE / nanoAg-C, Von-Ampe, stripping, simultaneous, metals.