It was found that multi-walled carbon nanotubes (MWNTs) could catalyze the redox reaction between chlorauric acid (HAuCl4) and reductive drugs such as tetracycline hydrochloride (TC), producing gold nanoparticles (Au NPs). By measuring the plasmon resonance light scattering (PRLS) signals of the resulting Au NPs, tetracycline hydrochloride can be detected simply and rapidly with a linear range of 4―26 μmol/L, a correlated coefficient (r ) of 0.9955, and a limit of detection (3σ) of 6.0 nmol/L. This method has been successfully applied to the detection of tetracycline hydrochloride tablets in clinic with the recovery of 101.9% and that of fresh urine samples with the recovery of 98.3%―102.0%.
