PITTCON 2011

Middleton Research is presenting Interaction of Hyperspectral Pixel Size and Optical Characteristics of Pharmaceutical Samples

Abstract: Pharmaceutical production samples have spatially non-uniform concentrations that need to be monitored to understand and improve the control of manufacturing processes. Hyperspectral push-broom line-cameras are one of the process analytical technologies (PAT) used to monitor continuously moving materials, producing full high resolution spectra of each point of a line at very high speed. Near-infrared hyperspectral imaging produces individual spectra from the diffuse reflection of adjacent rectangular areas as small as 4.5x10^-4 mm². Absorption and scatter characteristics, as well as shape and arrangements of the individual particles influence the depth of light penetration and signal correlation of adjacent pixels. Understanding the possible paths of the photons is possible using Monte-Carlo or similar optical simulation methods. Experimentally, pharmaceutically relevant materials were studied using a 4-stage cooled mercury-cadmium telluride (MCT) hyperspectral camera with 340x256 pixels. Using different magnifications the area of observation was increased while the crystal arrangements and illumination stayed the same. Different particle sizes in the 1000-2500 nm wavelength region were recorded with different particle arrangements, such as different crystals placed side-by-side or single particles positioned in a bed of different materials. Chemometric methods, such as hyperspectral unmixing, were used to study the separation and interaction of spectral signatures. New measurement possibilities and challenges for the monitoring of pharmaceutical formulations, such as blends will also be discussed.

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