Quantification of an Active Substance in a Tablet by NIR and Raman Spectroscopy

Abstract

Spectroscopic techniques in combination with chemometrics give opportunities to analyse tablets without time-consuming sample preparation. The aim of the present study was to develop a method to quantify the active substance, isosorbide-5-mononitrate, in Imdur® 120 mg tablets either by NIR diffuse reflectance or Raman spectroscopy. The calibration set was selected to simulate, with the available samples, as closely as possible a full factorial design with three factors. The reference method was liquid chromatography (LC). Calibration models with different baseline correction methods, different parts of wavelength range and different measures of weights have been evaluated. The calibration model found for each spectroscopic technique is discussed. The accuracy for the spectroscopic techniques were equal in merit to the LC method. Both the NIR and the Raman calibrations also showed a good long-term stability. With the baseline correction methods used for the spectra, it was possible to analyse tablets after 1.5 years. In conclusion it is possible to quantify Imdur® 120 mg with either NIR or Raman spectroscopy.