Optoelectronic Method of Test for Melamine Adulteration in Milk Using paraNitroaniline Modified Silver Nanoparticles

A simple and low cost method is proposed to quantify melamine adulteration in milk. This makes use of paraNitroaniline (p-NA) modified silver nanoparticles as the test probe. Two different nanoparticles are prepared using different p-NA concentration. The addition of melamine to the test probe produces aggregation of p-NA modified silver nanoparticle and hence accompanied by color changes from yellow to blue. The color being a representative of melamine concentration is picked up by optoelectronic technique and its dominant wavelength is arrived through CIE chromaticity chart. The test is performed on various concentration of melamine spiked milk. Same test procedure is performed in two different nanoparticles. Results of this study demonstrate better linearity and sensitivity for silver nanoparticles with higher concentration of p-NA. Color change and light intensity exhibit a correlation of more than 96% with a minimum of 4 µM of melamine concentration.