[Electroanalysis of nifedipine].

Nifedipine is an electrochemically active compound. Reducibility of 2-nitrophenyl group on dropping mercury electrode renders polarographic determination of nifedipine possible. Reductive half-wave potential of nitro group depends on saturation of neighbouring pyridine ring i.e. 1,4-dihydropyridine is reduced on more negative potential than aromatic pyridine derivatives. The different half-wave potentials can be explained with the different stereo structures. On this basis differential pulse polarographic (DPP) method was developed for determination of nifedipine and its photolytic decomposition products (its aromatic nitro and aromatic nitroso derivatives). The DPP method has been suitable for determination of pharmaceutical preparations (tablets and capsules) as well as for pharmacokinetic determination of plasma levels. The fact that 1,4-dihydropyridine functional group is oxidizable has made possible selective voltammetric determination of nifedipine (on graphic and platinum electrodes) and its EC detection in liquid chromatography. Mechanism of oxidation was studied with comparison to analogous chloro derivatives.