Magnetic ZnFe₂O₄ composite advances SERS assay for Patent blue V

Patent blue V (PbV) an Azo colorant because of its high toxicity to children has been severely limited in food industry. However, frequently the abuse of PbV in some artificial foods is still exposed by media. Current methods for the detection of PbV have to perform tedious pre-processing and the detection sensitivity and speed are required to be further improved.

In this work, we immobilize gold nanoparticles (Au NPs) on the surface of ZnFe₂O₄ with aid of Inositol hexaphosphate (IP₆) to prepare a novel magnetic surface-enhanced Raman scattering (SERS) substrate (designated as ZnFe₂O₄-IP₆-Au NPs) for rapid detection of PbV in beverages. Synergistic effect of magnetic enrichment, magnetic inducing improvement effect (MIIE) and efficient charge transfer (CT) enables ZnFe₂O₄-IP₆-Au NPs-based SERS assay to achieve limit of detection of PbV down to 1.31 × 10^-8 mol/L and a concentration linear relationship ranging from 8.6 × 10^-4 to 8.6 × 10^-8 mol/L. The detection recoveries for PbV in beverages locate in the range from 98.1 to 102.5 %, meaning the feasibility of method. In addition, the presence of IP₆ protection greatly improves the storage stability of ZnFe₂O₄-IP₆-Au NPs.

ZnFe₂O₄-IP₆-Au NPs substrates with excellent SERS performance could on-site, rapidly and sensitively detect PbV. As a perspective, magnetic-composite-based SERS assay has great scenario in food safety by using portable Raman spectrometer.