Portable colorimetric melamine detection device based on nanoparticle interference synthesis

Melamine is a toxic adulterant known to be mixed with milk to defy protein content tests. Monitoring this adulteration is infeasible in developing countries due to the high cost and limited availability of the established methods such as liquid chromatography, mass spectrometry etc. This work presents a portable melamine measurement device that utilizes a Single Board Computer (SBC) for image acquisition and processing to quantify color changes due to interference synthesis of gold nanoparticles. Melamine interferes with the nanoparticle (NP) synthesis by binding to the reducing agent (ascorbic acid) used in the instant synthesis of NP, leading to altered NP size distribution and aggregation. The resulting color change is assessed using on-board image processing to arrive at a test result within 10 seconds. The system can quantify as low as 0.1 ppm of melamine, while providing a linear response till 2 ppm - the permissible melamine limit in food. This unprecedented level of portability, instantaneous quantification and low cost qualifies the presented device as the most accessible melamine detection system yet. This would be very beneficial to milk producers and consumers alike.