Summary
Trace quantities of naphthoquinones and Methylene Blue are titrated with titanium (III) electrogenerated at a platinum cathode from an electrolyte of 0.4M titanium tetrachloride and 8M sulphuric acid, with potentiometric detection of the end-point. For naphthoquinones, 15–50% of methanol is added to prevent adsorption of the naphthohydroquinone product onto the generating electrode. For Methylene Blue, 2×10−6 M selenium(IV) is added as a catalyst and the titration is performed at 70° C to speed up the titration reaction.
Zusammenfassung
Spurenmengen von Naphthochinonen und von Methylenblau lassen sich mit Titan(III) titrieren. Dieses wird auf elektrochemischem Weg an einer Platinkathode aus 0,4-m Titantetrachlorid und 8-m Schwefelsäure gewonnen. Die Endpunktanzeige erfolgt potentiometrisch. Bei der Bestimmung von Naphthochinonen setzt man 15–50% Methanol zu, um die Adsorption von Naphthohydrochinon an der Generatorelektrode zu vermeiden. Für die Bestimmung von Methylenblau verwendet man 2 · 10−6-m Selen(IV)lösung als Katalysator und titriert bei 70° C, um die Reaktion zu beschleunigen.
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Viré, J.C., Patriarche, G.J. & Christian, G.D. Determination of naphthoquinones (K vitamins) and Methylene Blue with electrogenerated titanium(III). Mikrochim Acta 67, 17–22 (1977). https://doi.org/10.1007/BF01196524
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DOI: https://doi.org/10.1007/BF01196524