Rapid determination of trace nitrofurantoin in cosmetics by surface enhanced Raman spectroscopy using nanoarrayed hydroxyl polystyrene-based substrate

The safety of cosmetics attributing to the illegal addition of antibiotics for quick effect is a big concern nowadays. Nitrofurans, one of commonly added illegal antibiotics, are strictly banned in cosmetics in China. It is still a great challenge for the rapid and precise analysis of trace nitrofurans when facing various cosmetics with complicated matrices. Surface-enhanced Raman spectroscopy (SERS) is emerging as a novel rapid on-site analytical technique. In this work, an accurate SERS method was developed for the rapid analysis of trace nitrofurantoin in various cosmetics by use of nanoarrayed hydroxyl polystyrene (PS-OH)-based substrate. A series of characterizations indicated the successful synthesis of Au@PS-OH substrate and the uniform distribution of gold nanoparticles on the substrate surface. The SERS substrate revealed good selectivity and reproducibility with an enhancement factor of 2.6×104. Finally, an analytical method for the determination of nitrofurantoin in cosmetics was established by SERS using Au@PS-OH substrate coupling with efficient sample preparation process. It was satisfied that trace nitrofurantoin could be actually detected and quantified to be 1.77 and 7.74 mg/L in a mouthwash and rose-mist sample, respectively, with good recoveries of 86.8-106% and relative standard deviations of 0.9-2.9%. The comparable analytical results for real samples were achieved by the traditional high-performance liquid chromatography (HPLC) method, which validated the reliability of the proposed method. It is expected that this SERS method has great potential for the rapid and on-site analysis of trace additives in cosmetics.