p-Dimethylaminobenzaldehyde and urea in acid media give yellow colouration. The chromogen responsible for the yellow colour is Schiff-base(l). The structure of chromogen is illustrated with chemical and spectroscopic mean. The yellow colour absorb at gmax 420 nm. The fluctuation of yellow colour absorbance depends upon the strength of acid. Several minerial acids and their mixtures with different concentrations in methanol have been tried a reaction media, but, the CH3OH-H2SO4 mixture appears to be the best and yield good results. The optimum amount of H2SO4 (36N) 0.2 - 0,3 mi in CH3OH is found to be the best reaction media where reactants and products do not get precipitated. In it, the yellow colour remain stable and is used as an analytical tool for the determination of urea present in biological fluids. The % age of urea is calculated using p-dimethylaminobenzaldehyde, diacetylemono-oxime and urease (enzymatic) methods.
Z MAHMOOD ,R YASMEEN ,I HUSSIAN ,REHANA NASIR ,MUHAMMAD JAHANGIR ,RUHI HAMMED ,
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