“Lab-on-pol” colormatic sensor platforms: Melamine detection with color change on melamine imprinted membranes

There is an urgent need to improve a specific, equipment-free and user friendly technique for detecting melamine in food samples. Here, melamine imprinted polymeric membranes were synthesized, and tested for selectivity in aqueous solutions against cyromazine used as competitor agent, and real milk samples spiked with melamine. Scanning electron microscope, atomic force microscopy, energy-dispersive X-ray and optical profilometer devices were used for characterization. Fe+3 ions were used as marker to obtain color change based on melamine concentration. The color intensity on MIP membranes was monitored by means of a color analysis application (Image J software) via a smartphone. Some obtained results as fallows: Melamine binding to 3D cavities of membrane came true in about 20 min. The linear regression plot showed a correlation coefficient (R2) of 0.995 in the range of 10 μM-50 μM according to Beer Lambert's law. A low concentration of melamine, (e.g., 10 µM) was determined in raw milk. Melamine imprinted polymeric membranes showed 7.575 times more sensitivity for melamine than cyromazine. Limit of detection (LOD) and limit of quantification (LOQ) were computed as 9.9 µM and 30.2 µM, respectively. Here, a new kind of smart polymer was designed, and successfully applied for the easy, portable and on-site colorimetric analysis via imprinted polymers, and named as "lab-on-pol"system. HPLC analysis method was also used to validate this new analysis method.