The direct determination of creatine in pathological urine / by G.S. Walpole.

  • Walpole, George Stanley.
Date:
[1911?]
Catalogue details

Licence: Public Domain Mark

Credit: The direct determination of creatine in pathological urine / by G.S. Walpole. Source: Wellcome Collection.

    8/12 (page 306)
    has been altered very little by subsequent observers. E. Mellanby1 advocates plotting a curve once and for all, thus obviating the necessity of repeating the determination should the readings fall outside the range 5—12 mm. as Folin recommends. In connection with this curve it would appear at first sight that the accuracy of the determination is much greater with dilute than with concentrated solutions, but the fact that when the solution is more coloured the colorimeter can be adjusted with correspondingly greater accuracy leaves the order of magnitude of the error in reading constant over a very considerable range. The personal factor is a very great one in this method and a recent criticism by Taylor2, advocating a standard illumination, is very much to the point. The results given are for a number of pathological urines kindly supplied by Dr E. Mellanby, whose creatine determinations by the Folin method I have his permission to quote. TABLE I. Sample No. Creatine mg. in 10 c.c. by Folin’s method Creatine mg. in 10 c.c. by diacetyl method 1 1-2 2T 2 5'5 5-1 3 2-3 2-5 4 1-2 IT 5 4-0 5-0 6 2-0 3-0 7 4-5 3-0 8 0-8 1*5 9 2-7 3-0 10 2-7 3-5 11 5-2 3-5 12 4-4 greater than 6‘0 13 5*4 5-0 14 3*4 4-5 15 3-5 3-0 Such differences as exist do not point to any consistently higher values being given by one method than by the other. Further experi¬ ments are required to show which is the more accurate method of creatine determination. The absolute accuracy of the diacetyl method is possibly of the same order as that of the method of Folin. It might be considerably increased if the free ammonia of the urines was in each case determined and made up to a constant quantity. 1 E. Mellanby. This Journal, xxxvi. p. 453. 2 A. E. Taylor. Journ. of Biol. Chem. pp. 19-20. 1911.