SERS determination of the antihypertensive drugs prazosin and losartan by using silver nanoparticles coated with β-cyclodextrin

A surface-enhanced Raman scattering (SERS) method is described for the determination of prazosin (PRH) and losartan (LOS). Silver nanoparticles modified with β-cyclodextrin (CD-S-Ag NPs) were prepared and serve as a sensitive SERS substrate. β-CD is both a reductant for silver ions and a host molecule that binds the analytes which leads to strong SERS enhancement. The method has distinct features: (a) The linear response extends from 0.1 to 60 μM for PRH, and from 1.0 to 100 μM for LOS; (b) the respective limits of detection are as low as 15 nM and 0.92 μM; and (c) the specific SERS bands of PRH and LOS are located at 703 and 1298 cm −1 respectively. The method was successfully applied to the determination of PRH and LOS illegally added to healthcare products. The recovery of PRH and LOS from spiked samples ranges between 91.3 and 109.3%, and from 87.4 to 105.2%, respectively, both with relative standard deviation of <5%. Graphical abstract Schematic representation of a SERS method involving β-CD-S-Ag nanoparticles for determination of prazosin and losartan via formation of an inclusion complex.