Spherical silver nanoparticles as substrates in surface-enhanced Raman spectroscopy for enhanced characterization of ketoconazole.

A new method was developed for the characterization and detection of ketoconazole using surface enhanced Raman spectroscopy (SERS) by designing substrates and performing the bands' assignments. Thus, spherical silver nanoparticles (Ag-NPs) were synthesized by a reduction method and designed as substrates for SERS application. The Ag-NPs were characterized using a scanning electron microscope, Fourier transformed infrared spectroscopy and a high-resolution transmission electron microscope. TEM results indicated that the average size of the Ag-NPs was 15nm. The UV spectrum showed a maximum absorbance of Ag-NPs at about 400nm. When Ag-NPs were used as substrates in SERS, the Raman spectra of KCZ showed a significant enhancement of the Raman bands. An important finding is a linear relationship between the logarithmical scale of KCZ concentration and the intensity of the SERS bands, for example at 1050cm-1 of KCZ, which is due to the CN vibration. This was optimized and utilized to develop a calibration curve, which was then used for the detection of the KCZ in real pharmaceutical samples. The method has the advantages of a wide dynamic range with a high coefficient of determination and detection limit calculated based on the signal-to-noise ratio of 3, was 2.6×10-10 M and the limit of quantification was 7.8×10-10 M. The potential applications that take advantage of the high SERS sensitivity of this method are discussed for practical KCZ analysis where were quantified with this method.