Design and Development of Electro-Optic System for Quantification of Melamine Concentration in Milk

In this study optical property of paraNitroaniline (p-NA) functionalised silver nanoparticles (AgNPs) is explored for measurement of melamine adulteration in milk. When the whey protein of melamine spiked raw milk is extracted and added with the test probe, i.e., p-NA functionalisedAgNPs, colour of the solution changes. An electro-optical system is designed with time controlled red (R), green (G) and blue (B) light sources and sensing mechanism. Transmitted RGB values are measured for every sample and mapped on to international commission on illumination (CIE) chromaticity chart. To quantify the melamine concentration in milk, calibration algorithm is constructed by extracting features from chromaticity chart followed by distance measure and framing regression model. Result of the proposed method is in agreement with apriori values. When commercial milk with nitrogenous adulteration is tested, the system exhibits accuracy above 90% withlinearity from 4μM to 6mM and is able to measure as low as 0.5ppm. As a part of validation, the transmission intensity and absorption co-efficient measured by the developed system when compared with UV-vis absorption spectroscopy, correlation of 98% is achieved. Since milk being used widely, this newly developed electro-optical system with the suitable test probe proves to have potential of getting converted into product for societal benefit.