Urea Nitrogen Essay

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Urea Nitrogen Assay Introduction The end product of the protein metabolism is Urea. Urea is an organic compound that has two –NH2 groups attached to the carbonyl (C=O) functional group. It is odorles, colorless and highly soluble substance. It is also the main substance in urine containing nitrogen. Urea is syntetized in the liver as part of the urea cycle either from the oxidation of aminoacids or from ammonia. Ammonia, a common byproduct of the metabolism of nitrogen, is smaller, more volatile and more mobile than urea. Ammonia would raise the pH in cells to toxic levels when it is accumulated; therefore, many organisms convert ammonia to urea. Urea is a safe vehicle for the body to transport and excrete excess nitrogen. In water, water molecules displace the amine groups, producing ammonia and carbonate anion. For this reason, old urine has a stronger odor than fresh urine. In humans, the kidneys regulate urea. Besides carrying waste nitrogen, urea also plays a role in the countercurrent exchange system of the nephrons. Such system allows re-absorption of water and critical ions from the excreted urine. Urea is reabsorbed in the inner medullary collecting ducts of the nephrons. Urea is measured as Urea Nitrogen (Urea N) and constitutes 45% of the total non-protein nitrogen. Urea N in blood or urine is an important indicator of liver and kidney function. The concentration of urea N is determined by the use of Urease. In this experiment Urea was hydrolyzed in the presence of water and urease to produce ammonia and carbon dioxide. This method is based on the pH increase by urea hydrolysis by urease. The pH variation is monitored by a colorimetric quantification of the indicator dye o-cresolphthalein complexone. A blue indophenol compound proportional to the concentration of ammonia was formed when alkaline phenol and sodium hypochlorite reacted with

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