A phthalocyanine based sensor, for anodic detection of sodium ethylene bisdithiocarbamate (Nabam) by coating a mixture of cobalt phthalocyanine (CoPC) modified carbon ink on the surface of a glassy carbon electrode, has been described. The modified ink was prepared by mixing three percent of cobalt phthalocyanine into carbon ink and then diluting the mixture with cyclohexanone in w/w ratio of 1/9. A suitable portion (or 1 μL) of ink mixture was then dip-coated on a rotating disk glassy carbon electrode. The modified ink electrode was air-dried for 15 mins before use. In comparison to the bare ink electrode on which the oxidation of Nabam takes place at 300 mV (vs. 3 M Ag/AgCl), the oxidation potential (−125 mV) of Nabam at the CoPC modified ink decreases significantly. A typical calibration plot of Nabam proportionally increases over the concentration range of 2.5 to 36 μM (R=0.9990). The detection limit is estimated about 28.8 nM (S/N=3) and its response time (between 10% to 90% of steady-state response) is about 5.3 s at the injection of 5 μM Nabam. The sensitivity requirement of JMPR meeting (Joint FAO/WHO Meeting on Pesticide Residues) for ethylene bisdithiocarbamates (EBDCs) is achieved by this proposed scheme.
