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Nitrofurantoin (NFT), a typical highly effective nitrofuran antibiotic drug, has been prohibited but still widely found in animal food products. It can be metabolized in animals to form 1‐amino‐hydantoin (AHD) that can then form stable and toxic metabolite‐protein adducts. Hence, the detection of NFT and AHD in aquatic products and feeds is very important. However, there are limited reports concerning NFT detection and none about AHD by using surface‐enhanced Raman spectroscopy (SERS) method. Herein, potassium bromide (KBr) decorated silver (Ag) nanoparticles (Ag‐BrNPs)‐based SERS approach was proposed for NFT and AHD detection. The limit of detection (LOD) for NFT was 1 μg/L. The detection of NFT residues in sea cucumber and fish feeds was also realized with the LOD of 1 and 50 ng/g, respectively. More importantly, the sensing of AHD was easily realized with the SERS approach for the first time. After the derivatization with 2‐nitrobenzaldehyde (2‐NBA), Ag‐BrNPs were also successfully utilized for AHD detection in sea cucumber with the LOD of 5 ng/g.

2,2′,4,4′,6,6′-Hexanitrostilbene (HNS) is an explosive with better explosion performance than the well-known 2,4,6trinitrotoluene (TNT). Surprisingly, unlike other nitroaromatic explosives, there are limited reports regarding the detection of the HNS, let alone sensing reports on surface residues. In this work, a multifunctional flexible SERS sensor was proposed for the indirect detection of HNS based on the transparent fixate gel pads. The sticky and flexible gel pad can effectively collect any HNS surface residues. The inherent amine groups within the gel pad of which the main ingredient is polyurethane can react with HNS to form the orange Meisenheimer-alike complex. The modification of Ag NPs with halide ions was screened for the best SERS performance. KImodified-citrate-reduced Ag NPs showed selective but enormous SERS enhancement for the HNS derivative. The detection of HNS in the solution phase was explored, and a linear range of 0.01−25 ppm was achieved. The lowest detectable amount (LDA) of HNS was found to be 50 pg, making it one of the most sensitive methods in literature. It was successfully utilized for the HNS residues sensing on fingerprints and bags with LDAs of 5 and 200 ng, respectively. In addition, other explosives including TATB, LLM-105, RDX, HMX, FOX-7, and TNT were also examined to assess the selectivity of the fixate. It was found that the fixate showed excellent selectivity for HNS.

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