Spectroanalytical SERS-based detection of trace-level procainamide using green-synthesized gold nanoparticles

A highly sensitive approach based on surface-enhanced Raman scattering spectroscopy has been developed for the detection of the procainamide drug in water and spiked urine samples. Synthesized gold nanoparticles with small particle size (42.6 nm) were used as the active agent. The high plasmonic effect and charge transfer due to a strong interaction between procainamide and gold nanoparticles led to a gigantic enhancement of the Raman intensities. With the focus on PA-Au-NP system, density functional theory calculations were conducted to intricate the drug-substrate adsorption scenarios at a molecular level along with the corresponding exciting energies. Considerable intensity enhancements were detected for the Raman lines located at 1161, 1401, 1653, and 1690 cm⁻¹. These leading bands were further explored for the procainamide quantification in water and spiked urine samples. The developed approach posed an outstanding sensitivity with a wide linear range (0.1M–10⁻¹¹ M), high reproducibility, and stability with a relative standard deviation of 1.9% was achieved. The limit of detection for procainamide in aqueous media was 1 × 10⁻¹¹ M with a regression coefficient of 0.999. The interference study, using different interferents revealed that the reported analytical approach exhibited high selectivity for the quantification of procainamide.