Voltammetric Behaviour and Determination of Some Cytokinines on Mercury Electrode
aDepartment of Analytical Chemistry, Faculty of Science, Palacky University, bLaboratory of Growth Regulators, Faculty of Science, Palacky University and Institute of Experimental Botany, Academy of Sciences of the Czech Republic, Olomouc
Electrochemical behaviour of 6-(furfurylamino)purine (kinetin) and 6-(benzylamino)purine (BAP) on a mercury electrode was studied using classic DC polarography, cyclic voltammetry and fast-scan differential pulse voltammetry (FSDPV). The six-electron reduction of the mentioned cytokinines is irreversible and proceeds only in the protonated form. The electrode process starts with four-electron reduction of the pyrimidine skeleton. As a result of elimination of the amine from the side chain, one of the electrochemically active bond is re-established and the last two-electron step follows. The dissociation constants of the oxidized forms determined using UV spectrometry are: pKa = 3.73 ± 0.16 (kinetin) and pKa = 4.16 ± 0.19 (BAP). Kinetin 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 chromatography. The voltammetric determination is more precise in comparison with the used biotests.
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