Optimized core-shell Au@Ag nanoparticles for label-free Raman determination of trace Rhodamine B with cancer risk in food product

A simple and reliable method based on surface-enhanced Raman scattering (SERS) with a portable Raman system is described for sensitive determination of trace levels of Rhodamine B (RB) in hot sauce samples. The sodium salt of phytic acid (IP6) stabilized Au@Ag core-shell bimetallic nanoparticles are constructed and used as SERS substrate, yielding high Raman enhancement of RB. The limit of detection for RB in water is 5 nM (2 ppb), which is below China Exit and Entry Inspection and Quarantine Bureau's tolerance level of 5 ppb. Also, the proposed easy assay of IP6-Au@Ag NPs combining with portable Raman system could be applied for on-site monitoring RB in hot sauce.