Colorimetric Determination of Thioamide Drugs Based on the Surface Plasmon Resonance Band of Colloidal Silver Nanoparticles

In this article، we report a new method for the determination of two thioamide drugs، propylthiouracil (PTU) and methimazole (MMZ)، with unmodified silver nanoparticles (AgNPs). The method principle involves reducing overall surface charges of the AgNPs and subsequent aggregation of AgNPs by thioamide drugs leading to decreasing of the surface plasmon resonance (SPR) peak of AgNPs at 400 nm. The potential effects of relevant experimental conditions including pH، concentration of AgNPs and incubation time on intensity of SPR peak were investigated and optimized. Under the optimum conditions، the calibration graphs were linear in the range of 0. 05-1. 2 µgmL-1 for methimazole and 0. 02-0. 8 µgmL-1 for propylthiouracil، with corresponding limits of detection of 0. 01 and 0. 007µgmL-1 respectively. This method was successfully applied for the determination of PTU and MMZ in pharmaceutical products.