Rapid determination of propylthiouracil and methimazole by surface-enhanced Raman scattering based on sodium alginate-protected silver nanoparticles.

A rapid, ultrasensitive and selective method has been established to determine antithyroid drugs [propylthiouracil (PTU) and methimazole (MTZ)] by surface-enhanced Raman scattering (SERS). Silver nanoparticles (AgNPs) were synthesized by reduction of silver nitrate (AgNO3) with sodium alginate (SA) and were used as SERS substrates. Through optimization of the SERS conditions, including the volume of SA-protected AgNPs solution, pH of Britton–Robinson (BR) buffer solution and concentration of NaCl solution, linear responses were obtained for PTU and MTZ in the concentration ranges of 3.02 × 10−9–1.06 × 10−5 mol L−1 and 1.21 × 10−9–1.21 × 10−5 mol L−1, respectively. By the present method, the limits of detection (LODs) for the determination of PTU and MTZ were as low as 1.58 × 10−10 mol L−1 and 2.97 × 10−11 mol L−1. The method was successfully applied for the determination of PTU and MTZ in real samples. The recovery of PTU and MTZ from actual samples ranged between 97.20 and 104.80%, with relative standard deviations (RSDs) less than 3.63%.