Rapid and simultaneous detection of multiple illegal additives in feed and food by SERS with reusable Cu 2 O-Ag/AF-C 3 N 4 substrate.

Illegal additives can bring the economic benefit, resulting in the continuous irregularities in the use of illegal additives. In this study, a method for rapid, sensitive, and simultaneous detection of multiple illegal additives including enrofloxacin, malachite green, nitrofurazone, and Sudan Ⅰ in feed and food samples by surface-enhanced Raman spectroscopy (SERS) with Cu ₂ O-Ag/AF-C ₃ N ₄ composite substrate was developed. A Cu ₂ O-Ag/AF-C ₃ N ₄ composite substrate was prepared by reacting Cu ₂ O modified by AF-C ₃ N ₄ nanosheets with AgNO ₃ solution. The substrate has a limit of detection (LOD) of 1.29 × 10 ^-6 mg/L, a good linear relationship of between 10 ^-6 and 10 ^-2 mg/L, and an R ² value of 0.95 for Rhodamine B detection. Furthermore, the substrate showed high uniformity and reproducibility, with relative standard deviations (RSD) of 6.74% and 4.85%, respectively. Adding AF-C ₃ N ₄ nanosheets not only increased the enhancement effect of the substrate, which was 4.4 times of that before addition, but also endowed it with good self-cleaning characteristics owing to its excellent photocatalytic activity. The substrate can be reused, with over 80% of the original Raman signal strength remaining after four repeat uses. The SERS based on the above substrate was used to detect the illegal additives, the LOD of enrofloxacin, malachite green, nitrofurazone, and Sudan Ⅰ can reach 4.67 × 10 ^-4 mg/L, 2.57 × 10 ^-5 mg/L, 5.7 × 10 ^-7 mg/L and 6.92 × 10 ^-5 mg/L. The results reveal that this substrate has great application potential in feed and food safety.
Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
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