Design and development of electrochemical biosensor for the simultaneous detection of melamine and urea in adulterated milk samples

The consumption of melamine and urea contaminated cow milk causes indigestion, acidity, ulcers and kidney stones in humans. In this context, a highly sensitive acetylcholinesterase cyclic voltammetric biosensor based on zinc oxide nanospheres modified Pt electrode has been successfully developed for the simultaneous determination of melamine and urea in cow milk sample. The fabricated bioelectrode showed 100% permeability to the binary mixture of melamine and urea, which in-turn enhanced selectivity. In addition, linear regression models for the estimation of binary mixture of melamine and urea in cow milk were formulated by keeping added melamine and urea as dependent variables and the estimated electrochemical paremeters as independent variables. The prediction performance of linear regression models was validated using %recovery, relative prediction error and root mean square error for cross-validation. The developed Pt/ZnO/AChE/Chitosan bioelectrode detected melamine and urea over a range of 1–20 nM with a limit of detection of 3 pM and 1 pM respectively. The proposed sensor exhibited good recovery (99.96–102.22%), thus providing a promising tool for analysis of melamine and urea in cow milk samples.