Rapid detection of paraquat residues in fruit samples using mercaptoacetic acid functionalized Au@AgNR SERS substrate

An optimum SERS performance is mainly dependent on the development of innovative substrates that show high spectral reproducibility and stability. The current study involves the synthesis of core–shell nanorods ([email protected]) functionalized with mercaptoacetic acid (MAA) to increase the stability and sensitivity of the substrate for cost-effective and sensitive assessment of paraquat (PQ) residues in fruit samples. The morphological analysis of the substrate using TEM and STEM-EDS images indicated the uniformity in size and structure of the prepared nanoparticles. Further the modified substrate, MAA/[email protected] showed excellent stability and sensitivity in comparison with its unmodified counterpart. For the evaluation of PQ residues in pear and apple fruit samples the modified substrate exhibited R2 values of 0.9954 and 0.9914 with a low limit of detections of 0.012 and 0.024 ppm, and good percent recoveries of 80–110 % and 81–104 %, respectively. Thus, the study proved the effectiveness of the proposed MAA/[email protected] substrate for assessing residues of herbicide in complex foods.