Borodin Method

BORODIN METHOD for determination of urea, based on the decomposition of the latter by brominated alkali into water, N, and CO₂: carbon dioxide is absorbed by the alkali, and the content of urea is calculated from the volume of N released. The determination is performed in a special Borodin apparatus, shown in the figure. Reagents: 1) in 1 liter of water, dissolve 30 g of caustic soda and to the liquid add after cooling 50 g of bromine; 2) saturated solution of table salt. Method of execution. The apparatus is filled with solution (2) through tube B until it flows out into A above the stopcock. The stopcock is closed and the salt solution is released from A through the side opening of the stopcock. 5 cubic cm of urine, diluted 5 times with water, are allowed to flow from A into B above the salt solution, with which the urine does not mix due to the difference in specific gravity. Then, in small portions, brominated alkali (1) is introduced into B until the release of gas bubbles ceases. After 30 minutes, the volume of gas is measured. From tables, the amount of urea corresponding to 1 cubic cm of N at the existing temperature and pressure is found. The method is sufficiently accurate and is used for quantitative determination of urea in urine. For blood, this method was modified by Saveliev.