Protolytic properties of dyes embedded in gelatin films

Journal of the Brazilian Chemical Society

Nataliya A Nikitina¹  Elena A Reshetnyak¹  Nataliya V Svetlova¹  Nikolay O Mchedlov-petrossyan¹ 

[1] ,Kharkov V. N. Karazin National UniversityKharkov,Ukraine

关键词: dye-modified gelatin film;    indicators;    apparent ionization constants;    medium effects;   

DOI  :  10.1590/S0103-50532011000500007

来源: SciELO

【 摘 要 】

The hardened gelatin film fixed on the transparent triacetylcellulose support can be utilized as a convenient carrier for acid-base indicator dyes. Bromophenol blue, bromocresol green, eosin, ethyleosin, n-decyleosin, n-decylfluorescein, neutral red, and malachite green were embedded into the gelatin films by extracting from aqueous media under appropriate conditions. The light absorption of dye-doped films exhibits a response to the pH values of aqueous buffer solutions, where they were soaked in. The well-reproducible indices of the apparent ionization constants, pKa app, of the indicators were calculated by conventional equating the pH values of the bulk aqueous buffer and those of the 'internal' water into the gelatin films. The experiments with pH below and above the isoelectric point of gelatin (around pH 5) result in pKa app values, which resemble those in micellar media of cationic and anionic surfactants, respectively. The dye-modified gelatin films can be recommended for use in optical sensors and related devices

【 授权许可】

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