Collect. Czech. Chem. Commun. 1990, 55, 391-402

The coulometric titration of the derivatives of N,N-dimethyl-4-aminoazobenzene by generated trivalent titanium

Jiří Bareka, Helena Kvapilováa, Tibor Pastorb and Jiří Zimaa

a Department of Analytical Chemistry, Charles University, 128 40 Prague 2, Czechoslovakia
b Department of Analytical Chemistry, Belgrade University, 110 01 Belgrade, Yugoslavia


Conditions for the coulometric generation of titanium(III) ions in buffer medium in the presence of sodium citrate were found on the basis of a study of the electrochemical behaviour of the Ti(III)/Ti(IV) system. A current efficiency of 100% was attained in acetic acid solution (c = 1 mol l-1) containing citric acid (c = 0.2 mol l-1) and titanium (IV) chloride (c = 0.1 mol l-1), with pH adjusted to 6 using sodium hydroxide, in the current density range 0.5 to 10 mA/cm2 using a mercury electrode and 1 to 2 mA/ cm2 using a paraffin-impregnated spectrographic carbon electrode. It was found that methanol does not affect the current efficiency at contents of up to 33% (v/v) and conditions were found for the coulometric titration of small amounts (0.2-2 mg) of some genotoxic derivatives of N,N-dimethyl-4-aminoazobenzene.