Ultrasensitive Determination of Thiabendazole in Fruit Juice by Surface-Enhanced Raman Scattering (SERS) Using a Covalent Organic Framework (COF) Gold Nanoparticle (Au NP) Substrate

An effective and sensitive SERS substrate (TPDH-COF/Au NPs) on a covalent organic framework (TPDH-COF) decorated with gold nanoparticles (Au NPs) was fabricated via electrostatic self-assembly and successfully applied for the determination of thiabendazole (TBZ) in fruit juice. The "raspberry-like" structure SERS substrate combined the properties of the abundant "hot spots" between the Au NPs and the adsorption performance of TPDH-COFs for trace analytes. Excellent SERS performance was observed, which achieved a high enhancement factor value of 2.01 × 108 for rhodamine 6 G, with considerable reproducibility and excellent long-term stability of at least 28 d. The limit of detection was estimated to be 5 ppb for TBZ in fruit juice. The result demonstrated that the TPDH-COF/Au NPs have great potential for SERS analyses and determination of pesticide residues in foods.