Highly sensitive identification of illegal cooking oil by surface enhanced Raman spectroscopy combined with acyl nucleophilic substitution reaction to detect capsaicin

Abstract

Accurate discrimination of illegal cooking oil (ICO) remains a conundrum in the fields of analytical chemistry and food safety. Nevertheless, capsaicin can be regarded as a highly valuable exogenous signal molecule for the detection of ICO, owing to its resistance to removal from recycled kitchen waste oil. In this study, a simple and sensitive method for capsaicin detection was developed by integrating acyl nucleophilic substitution reaction with surface-enhanced Raman spectroscopy (SERS). Experimental conditions, including reaction temperature, time, and molar ratios, were found to significantly affect the derivatization reaction between 4-ATP and capsaicin. Quantitative analysis was performed based on the characteristic Raman peaks of the derivatized products.The intensity of the characteristic Raman peak has a linear relationship with the concentration of capsaicin (10-11-10-8 g/mL), and the correlation coefficient R2 is greater than 0.98. Combining SERS with the derivatization reaction of capsaicin, this method features high sensitivity and simple operation, exhibiting promising application potential in the detection of ICO.