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Solvatochromic and protolytic properties of the indicators in the solidified gelatin gel medium

2017; Elsevier BV; Volume: 529; Linguagem: Inglês

10.1016/j.colsurfa.2017.05.035

1873-4359

O. Yu. Konovalova, Elena A. Reshetnyak, T. B. Pochinok, P. V. Anisimovich, Н. А. Никитина, Nataliya V. Ivchenko,

Various Chemistry Research Topics

Fixed on the transparent triacetate cellulose substrate of the commercial film, the solidified gelatin gel was used for the immobilization of acid-base and solvatochromic betaine dyes. The results of microscopic studies showed that while immobilizing the reagents, the structure and morphology of the gel don't change. Indicators are distributed uniformly in the gelatin layer of the film. Polarity parameters (ET (30) and ETN) of the solidified gelatin gel film medium and gelatin gel on the glass substrate, obtained in vitro have been estimated on account of the shifts of the spectral absorption bands of the immobilized in the film Reichardt's betaine indicators. It was found that at pH far from the isoelectric point (pH 4.5), the polarity of the medium of the solidified gelatin layer of the film is in the intermediate position between the respective values of the acetone and ethanol. This polarity verges towards the polarity of such solvent media as nitromethane, pentan-2-ol, propylene carbonate. The influence of the gelatin matrix on the change, comparing with aqueous solutions, of the index values of the ionization constants of the acid-base indicators correlates in sign with effects, observed for the same indicators in micellar solutions of anionic and cationic surfactants. Films with immobilized dyes on it can be recommended for use in optical pH sensors when visual and spectrophotometric pH controlling.