Application of spectral-focusing-CARS microscopy to pharmaceutical sample analysis

Abstract

We implement spectral-focusing-CARS hyperspectroscopy to characterize pharmaceutical samples. The use of a dynamically-power-tuned supercontinuum seeding method combined with epi-detection of the CARS signals allows for broadband hyperspectroscopy and rapid single vibrational frequency imaging with microsecond pixel dwell times. The broad hyperspectral capabilities spanning about 3000 cm-1 of vibrational information allow for facile discrimination between ibuprofen, common polymorphs of acetaminophen, and starchy binders. Application of 3-D hyperspectral imaging on bare tablet forms reveals surface-bound processing of low-dose drugs such as cetirizine.