Investigation of ketoconazole diffusion into collodion membranes using step-scan FTIR-PAS technique

Results obtained from step-scan Fourier transform infrared photoacoustic spectroscopic (FTIR-PAS) experiments on ketoconazole diffusion into artificial dodecanol-collodion (DDC) membrane are presented. Measurements were performed for two frequencies of 13 Hz and 54 Hz at the spectral range (500÷4500) cm^-1. Both in-phase and quadrature components of photoacoustic signal were registered. Analysis of ketoconazole diffusion was carried out for 1512 cm^-1 line, whose intensity showed strong dependence on drug concentration. This analysis based on earlier proposed theoretical model of diffusion in a layered system. Experimental dependencies were fitted with theoretical curves using multiparameter fitting procedure. It allowed determination of the diffusion coefficient of ketoconazole in DDC membrane D = (2.1±0.5)·10^-9 cm²s^-1. Obtained results confirmed usability of step-scan FTIR-PAS techniques in investigations of diffusion processes.