Milk, a vital dietary staple globally, necessitates rigorous monitoring to ensure its safety and quality. Urea, a nitrogenous compound, is a critical parameter in this context, serving as an indicator of potential adulteration, animal health, and processing integrity. This research investigates and compares various methods for the precise determination of urea levels in milk, focusing on accuracy, sensitivity, and practicality. A biosensor was created by immobilising urease enzyme on a nylon membrane and attaching it to an ammonium ion selective electrode (AISE) which was characterised by FTIR and FESEM with particle size between 0.09μm-0.49μm.in diameter. The+ biosensor showed optimum response within 20s at pH 5.5 in 0.05mM urea conc. in sodium phosphate buffer and 40˚C. It exhibited excellent sensitivity of 38 mV/decade and LOD 0.001 mM, and linear range 0.001 to 0.80 mM. Analytical recovery of added urea which were found to be 99.8%, 101.04%, 108.35%, 103.9%, 98.99%, 104.7%, 99.93%, 102.34%, 101.76%, and 103.02%. It was found to be trustable and an easy method of testing purity of any milk.