Detection and classification of volatile fatty acids using surface‐enhanced Raman scattering and density functional theory calculations

Abstract Volatile fatty acids of acetic, butyric, lactic, and propionic acids play an important role in the methane fermentation process. Particularly significant amount of propionic acid presence in the process will influence the methane fermentation efficiency. Herein, zigzag‐aligned silver nanorods were designed as surface‐enhanced Raman scattering (SERS)‐active substrates to establish the classification of volatile fatty acids against the traditional poor sensitive and time‐consuming titration and gas chromatography methods. SERS and chemometric method of principal component analysis is used for the detection and classification of volatile fatty acids. Density functional theory calculations were performed to understand the Raman vibrations and compare with experimental observations and to aid in the assignments of spectral lines. For the first time, the authors have used SERS technique to classify the acids. The findings suggest that this method is of great potential in the field of methane fermentation from industrial waste.