Quanhong Ou,Biao Tang,Liqin Jiang,Mingcheng Han,Weiye Yang,Junqi Tang,Gang Liu
Carbosulfan gets easily decomposed into carbofuran and 3-Hydroxy carbofuran in vegetables and forms harmful residues. To detect the residues of carbosulfan in vegetables (for example, cowpeas), a super-sensitive method of surface-enhanced Raman spectroscopy (SERS) was used in this work. Silver sol was prepared as the SERS substrate. To solve the adsorption problem of carbosulfan on Ag nanoparticles, 2, 6-dichloroquinone-4-chlorimide (chromogenic agent), and sodium hydroxide were added in carbosulfan to generate a complex, which was then mixed with the silver sol in the best proportion to examine SERS spectra. According to density functional theory calculations, the spectral peak positions of carbosulfan were determined. The optimal mixing ratio of the complex and the silver sol to obtain the optimal SERS spectrum and the detection limit of carbosulfan were investigated. The ultra-sensitive detection of carbosulfan residues (8.7 × 10 -11 g/L) in cowpeas was realized. The results of this work indicate that SERS is a promising technique for detecting single-molecule pesticide residues in vegetables.
Si-qin-gao-wa HAN,Xinxuan CHEN,Chen ZHANG,Hang ZHAO,Shuang LIN,Yanhua ZHANG,Wu-Li-Ji HASI
Surface-enhanced Raman spectroscopy (SERS) has gradually proved to be a powerful tool with wide applications in various fields. Here, a simple and rapid SERS method was developed for the determination of ketamine in urine based on silver aggregates as a SERS substrate. Ketamine in urine were demonstrated by the SERS technique with silver sol aggregated by a 0.5 M NaBr solution. The limit of detection for ketamine in urine could be obtained as low as 7.5 ppm, and a linear relationship for ketamine in urine between the Raman intensity and the concentrations was achieved in the range from 7.5 to 150 ppm (R2 = 0.977). Additionally, the recovery of this method ranged from 95.7 to 104.9%, which laid a favorable foundation for the rapid and reliable quantitative detection of ketamine in urine. Therefore, this SERS approach with high sensitivity and simplicity has a great prospect for the real-world application of ketamine in urine.
Ultra-sensitive detection of target molecules by surface-enhanced Raman scattering (SERS) is crucial in a wide range of fields but remains a great challenge. In this work, we report a simple and effective protocol for obtaining highly SERS-sensitive probe by mixing iodide with silver sol. The specific iodide effect on the SERS sensitivity is systematically investigated. It is found that, iodide can effectively promote the SERS enhancement of anionic and cationic analytes, and I - ion has a higher activating effect on SERS than that of Cl - ion. The as-prepared SERS-active substrate demonstrates excellent enhancement for rhodamine 6G with a high Raman enhancement factor of 1.8 × 10 8 , which allows the detection limit of 1.0 × 10 -13 M. Our findings in this work should be important for the developing of SERS theory and ultra-sensitive detection applications.
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