A NEW COLORIMETRIC METHOD FOR THE DETERMINATION OF HYDROXYPROLINE AND ITS APPLICATION TO GELATIN HYDROLYZATES

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Abstract
Hydroxyproline is oxidized by sodium peroxide, if copper or cobalt is present, to give an unstable red chromogen which, in hot acid solution, can be condensed with isatin to form a stable red complex. The conditions are described which permit the direct application of this reaction to the quantitative estimation of hydroxyproline in acid or alkali hydrolyzates of gelatin. By this method moisture-free gelatin is found to contain 14.65% of hydroxyproline.