ABSOLUTE (CALIBRATIONLESS) CHRONOAMPEROMETRIC DETERMINATION WITH A MERCURY HEMISPHERICAL SEMIMICROELECTRODE

Amperometric determination of electroactive species not requiring cali bration described in this work is based on separation of linear and sp herical parts of limiting diffusion current of a determined substance to the hemispherical Hg-semimicroelectrode (radius 37.5 mu m). Charges transfered by these two components of current during experiment are c omparable for semimicroelectrodes and the determination error is accep tably low (<10%) for concentration interval 50-500 mu mol dm(-3). The calibrationless amperometric determination was verified with cadmium a nd lead. A new way of calculating optimum value of electrode radius to minimize the determination error is also presented.