Quantitative determination of stabiliser in a single base propellant by chemometric analysis of Fourier transform infrared spectra

The main constituent in a propellant is nitrocellulose, which by nature is unstable, and consequently it has to be stabilised with, e.g., diphenylamine. In order to determine the remaining shelflife of the propellant, the amount of stabiliser is determined. The method mostly used for this purpose, high-performance liquid chromatography (HPLC), is however complex and time consuming. Partial least squares calibration of the infrared spectroscopic profiles of the stabiliser and its derivatives in the propellant against their respective quantities (determined by HPLC) was tested to find out whether the quantitative determination of the above was possible. The initial results show that the cross-validated calibration model yields quantitative determination of the stabiliser and its derivatives within an error limit of 10% in predicted values. The correlation between the measured and predicted values was better than 0.94 for the stabiliser and its three first derivatives.