Near-infrared monitoring of roller compacted ribbon density: Investigating sources of variation contributing to noisy spectral data

Plots of ribbon envelope density measurement versus NIR spectral slopes. Envelope densities are average of three ribbon samples produced at each Roll Force/Blend combination. Spectral slopes are determined from individual NIR spectral results for 3 ribbon samples, each scanned 5 times by 4 probes. Left side panel shows spectral slopes colour coded according to the probe number that acquired the NIR spectra and the right side panel shows spectral slopes colour coded according to ribbon sample number. Blends 1-3 differed in the storage conditions of microcrystalline cellulose (MCC) prior to blending with lactose and magnesium stearate; Blend 1 (ambient (41% RH/20 °C)), Blend 2 (low humidity (11% RH/20 °C)), and Blend 3 (high humidity (75% RH/40 °C).198