Specific and sensitive detection of capsaicin for edible oils authentication using fluorescent molecularly imprinted silica particles

In this study, we developed two fluorescent molecularly imprinted polymers (FMIPs) for sensitive detection of capsaicin to distinguish the recycled edible oils. Utilizing a catalyst-free molecular imprinting approach and N -vanillylnonanamide (capsaicin analog) as the template, two types of FMIPs were synthesized utilizing fluorescent monomers coupled with fluorescein isothiocyanate (FFMIP) and rhodamine B isothiocyanate (RFMIP). Both FFMIP and RFMIP showed high selectivity (imprinting factors of 2.9 and 10.6, respectively) and specificity (cross-reactivity factors ranging from of 2.4–3.8 and 1.9–16.4, respectively) to capsaicin, which were superior to their positive control polymers of FFMIP-N and RFMIP-N synthesized using an ammonia catalyst. The FMIP-based detection systems could quantitatively analyze spiked capsaicin in edible oil with detection limits of 22–38 nM and a detection time less than 10 min. Besides, these FMIPs are easy to be produced in mass and cost-effective, offering a powerful tool for rapid detection of capsaicin in food authentication.