Rapid Determination of Rhodamine B in Chili Powder by Surface-Enhanced Raman Spectroscopy

A rapid, simple, and sensitive method for the determination of Rhodamine B in chili powder was established based on surface-enhanced Raman spectroscopy using citrate-coated silver nanoparticles as the substrate. This substrate was found to produce enhancement factors of 1.6 × 107 at 625 per centimeter. A portable Raman spectrometer was used allowing on-site measurements. The effects of the volume of silver nanoparticle solution, the volume of hydrochloric acid, the volume of Rhodamine B, and the mixing time were optimized. The linear dynamic range was from 0.2 to 20.0 micrograms per liter and the limit of detection was 0.08 microgram per liter. The method was applied to the determination of Rhodamine B in chili powder, with recoveries between 81.42 and 97.22 percent, and relative standard deviation values lower than 4.84 percent.