Noninvasive characterization of pharmaceutical solids by diode laser oxygen spectroscopy

The potential of using gas in scattering media absorption spectroscopy (GASMAS) for determination of physical and structural parameters of pharmaceutical solids was reported. High resolution diode laser spectroscopy allows detection of the narrow but weak absorption of molecular oxygen (at 760 nm). Each tablet was measured four times consecutively, and the average derived L_eq was presented. The porosity of pharmaceutical tablets was estimated by employing mercury intrusion porosimetry. Examined tablets exhibited oxygen absorption corresponding to 5-50 mm propagation through ambient air. Using the GASMAS technique, parameters such as porosity and particle size may be determined in raw materials as well as finished tablets.