The Estimation of Creatinine and Creatine in Diabetic Urines

That acetone and acetoacetic acid react with picric acid and sodium hydroxide with the production of a colored solution, similar to that produced by creatinine under the same conditions, has long been known. The extent of their possible interference with the estimation of creatinine, by the Folin method, has not been clearly determined. Folinl states that the reaction is’ given by hydrogen sulphide, acetone, acetoacetic acid and its ester, which, if present, may easily be removed. No directions are given. Klercker,2 who used very large amounts of acetone in his experiments, found that acetone caused a rapid fading of the color. According to van Hoogenhuyze and Verploegh3 the readings obtained in the presence of acetone are at first too low, but as the color due to the acetone fades rapidly, normal readings are soon obtained. Similar results are reported by Krause,4 who also investigated the action of acetoacetic acid. He found that the readings were too low. Wolf and Osterberg,5 on the contrary, reported that the addition of 1 per cent of acetoacetic ester was without influence upon the determination of creatinine. Rosea used acetoacetic acid in concentrations up to 0.25 per cent and obtained correct readings if the solutions were allowed to stand three or four minutes after dilution before making the readings.