Efficient On‐Site Detection of Simultaneous Adulteration of Paracetamol and Chlorpheniramine in Herbal Products Using Thin‐Layer Chromatography Coupled to Dynamic Surface‐Enhanced Raman Spectroscopy

ABSTRACT Chemical drugs illegally added to herbal products result in prominent health risks for users, especially frequent users of herbal dietary supplements. Onsite detection of pharmaceutical compounds adulterated in herbal products is crucial for ensuring product quality and safety. In this study, an efficient method that integrates thin‐layer chromatography (TLC) with dynamic surface‐enhanced Raman spectroscopy (DSERS) for the analysis of simultaneous adulteration of paracetamol and chlorpheniramine maleate in herbal products was developed. Silver nanoparticle colloids were used as SERS substrates and a dynamic SERS enhancer was optimized with a 10% glycerol solution. The optimized TLC‐DSERS method allowed more sensitive detection of chlorpheniramine, which is commonly adulterated at low concentrations. Typical SERS peaks were determined for the identification method without chemometric calculation of the spectral data, making the developed TLC‐DSERS method fast and simple. The validated TLC‐DSERS method was applied to 51 herbal samples collected from the Vietnam market, successfully identifying the adulteration of paracetamol or/and chlorpheniramine in 18 samples, among which four samples were simultaneously adulterated with both compounds. This method offers a practical, rapid, and sensitive solution for onsite analysis of paracetamol and chlorpheniramine illegally added to complex herbal products.