URINE 551 



(b) Total Sulphates (Inorganic and Ethereal). Measure 25 c.c. of urine 

 into an Erlenmeyer flask, add 2-2.5 c - c - of dilute HC1 (i 14) and 20 c.c. of water 

 and boil for 15-20 minutes. The ethereal sulphates are hydrolized. 1 Allow the 

 solution to cool and then precipitate the sulphate with benzidine as in the deter- 

 mination of inorganic sulphates. The titration and calculation are also carried 

 out in the same way. 



(c) Ethereal Sulphates. Determine the total sulphates and inorganic sul- 

 phates as indicated above. Subtract the amount of inorganic sulphate from 

 that of the total sulphate and obtain the amount of ethereal sulphate present. 



(d) Total Sulphur. According to Rosenheim and Drummond 2 the benzidine 

 method may be employed for the estimation of total sulphur in the solution ob- 

 tained on the oxidation of urine by the Wolf-Osterberg 3 modification of Bene- 

 dict's method. This modification involves the use of larger quantities of urine 

 than the Benedict method or a reduction in accuracy and hence probably has 

 no advantages over Benedict's original procedure. See below for modification 

 of Raiziss and Dubin. 



(e) Neutral Sulphur. Neutral sulphur is most readily determined by dif- 

 ference. Subtract from the total sulphur as determined by one of the methods 

 given above the amount of total sulphates. The difference corresponds to the 

 neutral sulphur of the urine sample examined. 



Interpretation. The neutral sulphur of the urine is made up of 

 cystine and related bodies, thiocyanate, oxyproteic acids, etc. It 

 makes up ordinarily from 5-25 per cent of the total sulphur of the urine, 

 or on the average 0.2 to 0.4 gram per day calculated as SOs. The 

 absolute amount is fairly constant for a given individual through wide 

 variations of protein intake, indicating that its origin is mainly en- 

 dogenous, that is, that it arises principally from the decomposition of 

 tissue protein. On this account the percentage of the total sulphur 

 excretion existing in the neutral form may rise to 25 per cent on a very 

 low protein diet and decrease to 5 per cent on a high protein diet, the 

 absolute amount remaining nearly constant. In fasting percentages 

 as high as 70 have been noted. In many disorders as tuberculosis, 

 cancer, cystinuria, etc., the amount may be relatively and in some 

 cases absolutely increased but no fixed relations have been determined 

 for the various conditions. 



7. Total Sulphur. Method of Raiziss and Dubin. 4 Principle. The urine is 

 oxidized by Benedict's method (page 548) the sulphur precipitated as benzidine 

 sulphate and the benzidine titrated with N/io permanganate solution. Very 

 small amounts of sulphur may be determined in this way. 



Procedure. To 2 c.c. of urine in an 8 cm. porcelain dish, add 0.5 c.c. of Bene- 

 dict's reagent (page 548) and evaporate to dryness on the water-bath. Heat the dish 



1 A larger amount of HC1 may be used (20 c.c. of the dilute acid) if desired. In this 

 case it is necessary to neutralize the solution carefully after boiling and again add dilute 

 HC1 until the reaction is acid to Congo red. 



2 Rosenheim and Drummond: Bioch. Jour., 8, 143, 1914. 



3 Wolf and Osterberg: Bioch. Zeit., 29, 429, 1910. 



4 Raiziss and Dubin: Jour. Biol. Chem., 18, 297, 1914. 



