Applications of attenuated total reflection infrared spectroscopic imaging to pharmaceutical formulations

This paper demonstrates an approach to obtain chemical images of pharmaceutical tablets using attenuated total reflection infrared (ATR-IR) spectroscopy. FT-IR images with different fields of view and spatial resolution have been obtained using a combination of different ATR accessories. FT-IR imaging with the diamond ATR accessory and micro-ATR imaging technique have been compared. With the diamond ATR imaging accessory, compaction to a tablet can be performed and the chemical image measured in situ. It has been found that the diamond ATR imaging accessory gives information on the overall distribution of different components in a tablet while the micro-ATR imaging technique provides a closer look at the tablet with 4-microm spatial resolution. Low-concentration components down to 0.5% have been detected by the micro-ATR method. Both experimental and commercial systems are studied in this paper.