Fluorimetric Fingerprinting with Magnetite–Particle–Fluorophore Sandwich Systems for Dairy Authentication and Adulteration Detection

Abstract

A fluorimetric fingerprinting method was developed for distinguishing dairy product samples according to their manufacturer and for detecting adulteration. The approach is based on the use of magnetite–particle–fluorophore sandwich systems formed through the interaction of polyhexamethylene guanidine-modified magnetite particles with milk components, followed by the addition of a fluorophore (carbocyanine dyes or carbon dots). The resulting sandwich systems were separated from excess fluorophore using a magnet, and the fluorescence of the aggregates was recorded photographically. The photographs were then digitized, and the resulting data were processed using chemometric methods. For comparison, the proposed method was evaluated against two alternative approaches: one based on the intrinsic fluorescence of the samples and the other based on the fluorescence of fluorophore-supplemented samples without magnetic separation. The proposed approach enables highly accurate detection of dairy product adulteration using common adulterants (100% accuracy) and discrimination of samples according to their manufacturer (93%).