A self-referenced method for determination of patulin by surface-enhanced Raman scattering using gold nanobipyramids as the substrate

A novel surface-enhanced Raman scattering (SERS) probe was developed for the selective determination of patulin using gold nanobipyramids as the SERS substrate. Patulin undergoes a selective chemical reaction with sulfhydryl groups of 4-mercaptobenzoic acid (4-MBA) to form new compounds. A substantial change of the SERS spectrum of 4-MBA was observed and a new peak at 1641 cm−1 appeared. A significant increase in the intensity of the SERS signal at 1641 cm−1 was observed upon addition of more targets. This feature was exploited for sensitive quantification of patulin in aqueous solution by ratioing the intensities of the new peak at 1641 cm−1 and the peak of 4-MBA at 1586 cm−1. This method displayed excellent selectivity for patulin. Under optimal conditions, the ratioed signal intensity is related to the concentration of patulin in the range between 10 μg L−1 and 3000 μg L−1, with a detection limit of 6 μg L−1. This method was successfully used for the determination of patulin in juice.