GOPKINSA METHODS ( F. G. Hopkins , English biochemist, 1861 — 1947):
I \quantitative definition of uric acid in urine;
II \qualitative test of tryptophane in cerebrospinal liquid.
I. A method of quantitative definition uric to - you in urine it is based on titration by potassium permanganate uric to - you, besieged in the form of urate of ammonium.
Reactants: solution of 500 g (NH 4 ) 2 SO 4 in 600 ml of H 2 O; solution of 5 g of uranyl acetate in 100 ml of H 2 O; solution for washing of a deposit: 100 g (NH 4 ) 2 SO 4 in 99 ml of H 2 O and 10 ml of 25% of solution of ammonia; konts. sulfuric to - that.
Course of definition. To 6 ml of urine add 2 ml of solution of the uranyl acetate containing ammonium sulfate, and filter a deposit. Add 10 — 15 drops of 25% of ammonia to 7,5 ml of a filtrate and leave for days for full sedimentation of urate ammonium. The deposit is washed out special solution for washing. To the washed deposit flow 3 — 4 ml a dist, waters and 1 ml konts. a chamois to - you, stir hot solution and titrate 0,02 N solution of potassium permanganate before emergence of the pink coloring which is not disappearing during 10 sec. Calculation is made on a formula:
where V T — number of ml of 0,02 N of solution of potassium permanganate; V M — the volume of the urine taken for definition; With — the number of mg of % uric to - you; 3 — allowance for solubility of urate ammonium (per 6 ml of urine).
Normal at the person with urine 0,2 — 0,6 g uric to - you in days are allocated. Allocation uric to - you increase at patol, the states which are followed by the strengthened disintegration of cells (leukemia, leukocytoses, fever, pneumonia, burns). Increase in allocation uric to - you is characteristic at nephrites, gout.
II. A method of qualitative test of tryptophane in cerebrospinal liquid it is based on definition of intensity of the violet coloring appearing at interaction of tryptophane with magnesium oxalate in acid medium.
Reactants: solution of magnesium oxalate — 250 ml of saturated solution oxalic to - you add to 10 g of powdery metal magnesium, after the termination of gas evolution filter in a volumetric flask on 1 d, addition ice acetic to - you lead up reaction of the environment to acid (on litmus), and bring the volume of solution to 1 l. Konts. sulfuric to - that.
Course of definition. In a test tube pour 5 ml of magnesium oxalate and add 2 ml of cerebrospinal liquid, slightly stir up and carefully layer 1 ml konts. a chamois to - you. In the presence of tryptophane on border of liquids the ring of violet color appears. Reaction is negative if the ring of brown color appears.
This qualitative test is used as the additional test at differential diagnosis of tubercular meningitis (see), at Krom it is positive; other forms of meningitis are characterized by negative test on tryptophane.
Bibliography: The guide to clinical laboratory trials, under the editorship of E. A. Kost and L. G. Smirnova, page 398, M., 1964; H about p k i n s F. G. On the estimation of uric acid in the urine (Hopkins’ method), J. Path. Bakt., v. 1, p. 451, 1892—1893.
H. V. Prokazova.