酵母製造に關する研究 (III) : 尿素の新しい簡易定量法について

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When urea is used as the nitrogen source in yeast manufacturing, it is necessary to determine the urea content in fermenting media rapidly as well as briefly. From this point of view, several methods hitherto proposed have been examined, with the consequence that the method using phenol and sodium hypochlorite is best suited to determine urea added to molasses and synthetic media.This method involves a colorimetric determination of urea and is based upon the bule-green color produced when sodium hypochlorite is added to urea in the presence of phenol. This system exhibits a transmittancy minimum at 410 mμ and shows good agreement with BEER's law at urea concentrations up to 0.0125%. With the instrument and procedure used, a relative error of 3.6% is realized over the optimum urea concentration range of 0.001 to 0.01%.The procedure of this method is as follows : Place 1 ml of the urea solution (0.001〜0.01% urea) in a test tube. Add 1 ml of 5% phenol and 1 ml of 4% sodium hypochlorite solution and mix by lateral shaking for 30 sec.. After standing for 4 min., add 5 ml of n-butanol and mix again by lateral shaking. Transfer the butanol layer into a cuvette. Read the optical density immediately. Prepare a blank by substituting 1 ml of distilled water for the urea solution, and set at O absorbance.
公益社団法人日本生物工学会の論文
1955-02-15