Measurement of the cumulative particle size distribution of microcrystalline cellulose using near infrared reflectance spectroscopy

The cumulative particle size distribution of microcrystalline cellulose, a widely used pharmaceutical excipient, was determined using near infrared (N IR) reflectance spectroscopy. Forward angle laser light scattering measurem ents were used to provide reference particle size values corresponding to d ifferent quantiles and then used to calibrate the NIR data. Two different c hemometric methods, three wavelength multiple linear regression and princip al components regression (three components), were compared. For each method , calibration equations were produced at each of eleven quantiles (5, 10, 2 0, 30, 40, 50, 60, 70, 80, 90, 95%). NIR predicted cumulative frequency par ticle-size distributions were calculated for each of the calibration sample s (n = 34) and for an independent test set (n = 23). The NIR procedure was able to predict those obtained via forward angle laser light scattering.