Practical organic and bio-chemistry / by R.H.A. Plimmer.

  • Robert Plimmer
Date:
1915
Catalogue details

Licence: Public Domain Mark

Credit: Practical organic and bio-chemistry / by R.H.A. Plimmer. Source: Wellcome Collection.

    607/660 page 587
    A little water is poured upon the filter followed by the alkaline solution containing the cuprous oxide. It percolates through in about 2 minutes; if it passes through more rapidly, more asbestos should be put into the crucible. The flask is washed with a few c.c. of boiling water poured upon the crucible and asbestos. The filter flask is removed and thoroughly washed out, the boil- ing flask is cooled, 5 c.c. of the ferric sulphate solution are put into it and shaken round to dissolve cuprous oyide; about 3 c.c. of it are poured down the sides of the crucible and upon the asbestos; the asbestos is sucked dry, the remainder is put into the crucible and sucked dry and the flask is washed with ro c.c. of distilled water which is poured upon the crucible: the last drop of wash water is sucked and pressed out of the asbestos by the aid of a glass rod. The solution is titrated with ‘o2zN permanganate contained In ARrOwc. burette until there is a distinct reddish tinge. The amount of glucose corresponding to the permanganate is found by reference to the table which has been specially compiled for this procedure p. 604). me average glucose content of normal human blood was found by this method to be (1) 063, (2) ‘098, (3) ‘og5 per cent. ; of diabetic blood -22 per cent; The method is not delicate enough to estimate traces of glucose, ie. less than ‘oz per cent. This does not arise with human blood which contains from ‘o5 to ‘15 per cent. In order to estimate small amounts by this method Gardner and Maclean adopt the expedient of adding 1 mgm. of glucose to the filtrate from blood and deducting this amount at the end. The glucose is most conveniently added by introducing it into the copper sulphate solution. This is specially prepared containing ‘1 per cent. 1 c.c. of the solution is added to the flask and the cylinder is washed out with the alkaline tartrate solution alone. Amounts of o’or per cent. or less can be determined in this way. Bang’s Micro-Method. Bang! has adapted his second method (p. 230) for estimating glucose in 2-3 drops of blood. ‘This method has been found to be satisfactory by Gardner and Maclean who have made one or two important modifications. It is carried out as follows :— The drops of blood are soaked up in weighed pieces of filter paper” 12 X 25 mm. in size and 1 mm. thick weighing about roo mgm. and weighed. The weighing is most conveniently effected with a torsion balance? The paper containing the blood is placed for 3-5 minutes in an oven at go- too to coagulate the proteins. ‘The glucose contained in the blood is extracted by immersing the paper in 7 c.c. of a solution containing 150 c.c. of saturated potassium chloride solution, 70 c.c. of water, and 2-3 drops of 40 per cent. acetic acid for 45 minutes to 1 hour, during which time it is raised twice to the boiling-point. ‘The solution is poured into a 50 c.c. Jena glass flask with a straight neck and no rim. ‘The paper is again boiled out with 4 c.c. of the above solution in the same way and this is put into the flask. 3 c.c. of the alkaline copper solution (see p. 611) areadded. ‘The flask is closed with a piece of rubber tubing 3 mm. thick and 4-5 cm. long leaving 2 cm. over, 1 Biochem. Zs., 1913, 49, I; I914, 57, 300. 2No. 264a. Made by Finbruken, Stockholm, It must be boiled out several times with water containing a few drops of acetic acid until a test experiment shows that it contains no reducing substances. 8 By Hartmann and Braun or Warmbrunn and Quilitz.
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