ADSORPTIVE-CATALYTIC STRIPPING VOLTAMMETRY-ENHANCED REDUCTION CURRENTOF ADSORBED CO-II TETRAAZA[L4]ANNULENE COMPLEX IN THE PRESENCE OF CO2

The macrocyclic cobalt(II) complex CoL (LH(2) = dihydrodibenzo[b,i][1, 4,8,11]tetraaza[14]annulene) can be adsorptively preaccumulated on mer cury electrodes from highly diluted aqueous solutions. The adsorbed Co complex undergoes one-electron reduction with subsequent protonation of [CoL](-) to CoLH, also adsorbed on mercury. The electrode covered w ith adsorbed complex may be used to detect CO2, since upon substitutio n of argon by CO2 a large catalytic peak is observed at the potentials of CoLH complex reduction. At constant CO2 concentration, the peak fi rst increases proportionally to the extent of coverage of the electrod e with the adsorbed complex and then becomes constant when monolayer c overage is attained. At a monolayer covered electrode the catalytic re duction signal increases proportionally to the increase of CO2 concent ration. The usefulness of the normal pulse voltammetry version of the adsorptive-catalytic stripping procedure is also shown.