Voltammetric behaviour and determination of some cytokinines on mercury electrode

Electrochemical behaviour of 6-(furfurylamino)purine (kinetin) and 6-(benzy lamino)purine (BAP) on a mercury electrode was studied using classic DC pol arography, cyclic voltammetry and fast-scan differential pulse voltammetry (FSDPV). The six-electron reduction of the mentioned cytokinines is irrever sible and proceeds only in the protonated form. The electrode process start s with four-electron reduction of the pyrimidine skeleton. As a result of e limination of the amine from the side chain, one of the electrochemically a ctive bond is re-established and the last two-electron step follows. The di ssociation constants of the oxidized forms determined using UV spectrometry are: pK(a) = 3.73 +/- 0.16 (kinetin) and pK(a) = 4.16 +/- 0.19 (BAP). Kine tin and BAP were determined using FSDPV in model samples as well as in real samples of the medium used for cultivation of plants in vitro. The analyte was concentrated by ion exchange, gel permeation, adsorption or affinity c hromatography. The voltammetric determination is more precise in comparison with the used biotests.