The matrix effect derived from proteins in fluorescence detection for ciprofloxacin residues in eggs

Based on the previously developed Al³⁺/CuNCs probe, the matrix effect (ME) derived from protein was investigated in the fluorescence determination of fluoroquinolones (FQs) residues in eggs, and a sample pretreatment method was established to rapidly reduce the ME. Molecular docking results indicated that the three main egg proteins and FQs were bound by hydrogen bond, van der Waals force, and alkyl groups, leading to the loss of FQs response signal, and then produced ME. After trichloroacetic acid treatment, the mean particle size of egg matrix decreased, the protein secondary structure changed, and the crystal structure was destroyed. The corresponding ME of the supernatant obtained by centrifugation was only 0.7 %. The standard addition experiment confirmed that the proposed pretreatment method improved the accuracy and reliability of the fluorescence probe. This work is helpful to promote the practical application of fluorescence analysis in the rapid monitoring of food safety hazard factors.