Determination of Captopril in Drugs by Resonance Scattering Spectrometry Based on CuSCN Particles

In HOAc-NaOAc buffer solution of pH 4.8, Cu(Ⅱ) was reduced by captopril to form Cu(Ⅰ), and then Cu(Ⅰ) reacted with SCN^- to form CuSCN particles, which made the resonance scattering (RS) signal increase drastically. The enhanced RS intensity (ΔI_RS ) at 398 nm was proportional to mass concentration of captopril in definite range. Based on the fact, resonance scattering spectrometry was applied to the determination of captopril in drugs based on CuSCN particles. The optimized conditions found were as follows:① amount of 0.50 g·L^-1 CuSO₄ solution was 1.50 mL;② amount of 0.50 g·L^-1 KSCN solution was 2.00 mL;③ time of reaction was 10 min. Linearity range of captopril was found in the range of 0.40-24.00 mg·L^-1, with detection limits (3σ) of 0.14 mg·L^-1. Tests for recovery were made by standard addition method at the concentration level of 1.00 mg·L^-1, giving values of recovery and RSDs (n=5) in the ranges of 97.0%-104% and 1.6%-2.7% respectively.