PHENOLSULPHONEPHTHALEIN TEST 81 



rated to low volume in a large evaporating dish on the water-bath. 

 Transfer to a small evaporating dish. Heat to dryness on the 

 sand-bath and then char, using a small flame. Transfer the charred 

 mass by means of a glass spatula to a crucible. The remaining 

 material in the evaporating dish is transferred with the aid of a 

 little hot water and a rubber " policeman " to a second crucible. 

 Evaporate to dryness on the water-bath and then ash the material 

 in both crucibles. Dissolve the ash in about 30 c.c. of iron-free 

 hydrochloric acid, transfer to an Erlenmeyer flask, add 2 c.c. of 

 hydrogen peroxide and boil for three-quarters of an hour. After 

 cooling, 2 gms. of potassium iodide and a few drops of fresh starch 

 paste are added. The liberated iodine is titrated with N/100 

 thiosulphate solution. Controls should be run on reagents. A 

 correction of 0.32 mg. is usually necessary for the undecomposed 

 hydrogen peroxide. The thiosulphate solution is made up as needed 

 from an N/10 stock solution by dilution. It is standardized 

 against an iron solution containing 2 mg. of iron in 10 c.c. The 

 number of cubic centimeters of thiosulphate used in titration of 

 the iodine set free from the ash solution is multiplied by the iron 

 equivalent of 1 c.c. of the thiosulphate (about 0.2 mg.) to obtain 

 the total amount of iron in the twenty-four-hour specimen of urine. 

 From 1-5 mg. of iron are usually excreted per day. 



This test for renal function was devised by Rowntree and 

 and Geraghty. 2 It depends upon the injection into the tissues 

 of a dyestuff which is eliminated rapidly by the normal kidneys, 

 and can be easily estimated quantitatively in the urine. 



This dyestuff, phenolsulphonephthalein, is non-irritative to 

 the body either when taken by mouth or when injected into the 

 tissues, so that it does no harm to an already weakened kidney. 



The patient upon whom the test is to be performed is given 

 300-400 c.c. of water twenty to thirty minutes previously, in order 

 to assure a free flow of urine. 



The procedure is as follows: One c.c. of a solution containing 



1 Hawk: Practical Physiological Chemistry, Sixth Edition, 1918. 

 2 Rowntree and Geraghty: Jour. Pharm. and Exper. Therap., 1910, 1, 

 579: also Arch. Int. Med., March, 1912, p. 284. 



