Rapid and direct detection of illicit dyes on tainted fruit peel using a PVA hydrogel surface enhanced Raman scattering substrate

A simple and fast method has been proposed for the direct identification of Sudan red adulterated fruit using a hydrogel SERS substrate. A kumquat dyed with Sudan red at a level of dozens of ppb was successfully detected using the proposed method even after 4 weeks of storage and verified with HPLC.