Tailored Imprinted Polymers for Selective Recognition of Sulfonated Dyes: Extraction of dyes from Soft Drinks, Water and Food Samples

Abstract

Synthetic sulfonated food dyes in beverages and processed foods pose health and environmental risks due to their persistence and potential toxicity, whereas traditional detection methods lack selectivity and involve excessive solvent use. We report synthesis of molecularly imprinted polymers (MIPs) with high affinity and enhanced binding capacity using phenyl sulfonic acid (PSA) as a template, a tweezer-type bis-imidazolium functional monomer, 2-hydroxyethyl methacrylate (HEMA) co-monomer, and ethylene glycol dimethacrylate (EGDMA) crosslinker. The PSA MIP recognition ability evaluated via rebinding isotherm data, fitted to the mono-Langmuir isotherm model revealed binding capacity in a range of 100 -300 µmol g -¹ with 10 ³ -10 ⁴ M -1 affinity in both organic and aqueous solvents. The polymer exhibited a superior affinity to structurally diverse sulfonated dyes containing a PSA substructure, demonstrating its ability to recognize commercial dyes in water, soft drinks, and food samples, including the successful capture of adulterated food dye from turmeric. As a proof of concept, class-selective MIPs were employed as adsorbents in solid-phase extraction cartridges, effectively capturing trace amounts of sulfonated dyes from water, highlighting their potential for food monitoring and environmental applications.