J. Heyrovský, Japan, and organic polarography.

Polarography is an electroanalytical technique based on recording current-voltage curves using a dropping mercury as the working electrode. It can be used for investigations of both reductions and oxidations of inorganic and organic species. Before WWII the developments of this technique linked Prague (in the then Czechoslovakia) with Kyoto (in Japan, where reductions of organic compounds were first observed).

Nucleophilic attack by bromide ions as a first step of conversion of Se(VI) to Se(IV).

Numerous commonly used analytical methods allow only determination of a total amount of selenium in a given sample. Electroanalytical methods as well as those based on hydride generation or on formation of piazselenol allow only determination of Se(IV). To determine Se(VI) by these procedures, present alone or in mixtures with Se(IV), it is first necessary to convert Se(VI) to Se(IV).

Reactions of orthophthalaldehyde with ammonia and 2-aminoethanol.

Reactions of orthophthalaldehyde (OPA) with amines are used in the determination of amino acids and in applications of OPA as a biocide. To contribute to the understanding of processes involved, the reactions of OPA with ammonia, which are conveniently slow, were studied. In a set of rapidly established equilibria, the 1,3-dihydroxyindole and the product of its dehydration are formed (Scheme 1).

Electrochemical determination of HIV drug Abacavir based on its reduction.

Abacavir (I), a drug used in the treatment of HIV, is electrochemically reduced at the dropping mercury electrode in a four-electron process, similar to structurally related adenine (III) and adenosine triphosphate (IV). To undergo the reduction, the species is protonated in the vicinity of the electrode. The protonations take place on the 6-amino group and on one of the pyrimidine ring nitrogens.

Existence and reactivity of three forms of orthophthalaldehyde in aqueous solutions. Polarographic, voltammetric, and spectrophotometric study.

Orthophthalaldehyde (1,2-dicarboxaldehyde) (OPA) forms in the presence of a strong nucleophile with amino acids isoindole derivatives. The reaction is used in fluorometric determination of amino acids. The mechanism of these processes is not understood.

Strong covalent hydration of terephthalaldehyde.

Spectrophotometric and electroanalytical studies indicate that one of the formyl groups of terephthalaldehyde in aqueous solution is present in about 23% as a geminal diol. Stronger covalent hydration of CHO in terephthalaldehyde than in p-nitrobenzaldehyde is attributed to a strong resonance interaction between the two formyl groups.

Electroreduction of aromatic oximes: diprotonation, adsorption, imine formation, and substituent effects.

Aromatic oximes are reduced in aqueous solution in a four-electron process. The reducible species in the pH range 5-8 is a diprotonated form of the oxime. This species is generated in the course of electrolysis in the vicinity of the electrode surface from the adsorbed neutral form of the oxime.