Hydrophilic fast-absorbing platform, filled with molecularly imprinted polymers

The aim of the work was to reduce the time for detection the concentration of phenol in aqueous solutions using colorimetric sensor systems based on molecularly imprinted polymers (MIPs). To achieve this goal, hydrophilic fast-absorbing platform (HFP) containing sodium carboxymethyl cellulose (Na-CMC) and hydroxyethyl methacrylate (HEMA) was developed. On the basis of HFP filled with crushed phenol-selective MIP a colorimetric test system was obtained. It provides increased sorption characteristics, significantly reduces the exposure time in aqueous solutions, and when interacting with the appropriate reagent generates an easily registerable colorimetric sensory response. The idea of creating a sensor system for ultra-fast out-of-laboratory deteсtion of phenols was based on the capability of HFP to absorb rapidly large quantities of liquid as well as on the ability of the molecularly imprinted polymer as a filler to bind selectively the analyte compound (phenol) and to generate a colorimetric sensor response upon interaction with the appropriate reagent. Bound to MIP phenol was further detected by the reaction with 2 % aqueous solution of 4-aminoantipyrine and 2 % aqueous solution of K3[Fe(CN)6] in alkaline medium. The intensity of the color from slightly pink to dark crimson was proportional to the concentration of phenol in the analyzed sample. Digital images of stained samples were obtained using the camera of a Samsung Galaxy J7 SM-J700H Gold smartphone equipped with the Android 5.1 operating system. The color intensity was measured by means of Color Grab software (version 3.6.1, Loomatix) in the RGB color model. The degree of swelling (?) was defined by gravimetric method. The morphology of the samples was studied by scanning electron microscopy (SEM) method using a MIRA 3 microscope (Tescan GmbH, Czech Republic). The use of HFP/MIP with a sensor system based on phenol-selective MIP reduces the time for phenol analysis by an order of magnitude (from 3 hours to 15 minutes). The limit of phenol detection by the developed sensor system is 2.5 ?M, while the working range is 2.5 ?M – 10 mM.