From lab to plant: a scale-independent NIR calibration to monitor an ionic exchange column

A near-infrared (NIR) spectroscopic quantitative method based on a transmission technique was developed for monitoring the outlet concentration of an active pharmaceutical ingredient (API) in an ionic exchange elution process. A partial least squares (PLS) calibration model was built, after wavelength selection and spectra pre-processing optimisation (aqueous samples with variable matrix). The calibration data set was based only on samples obtained from lab scale experiences. An external validation on different process scales showed very good predictive capability regardless of scale and matrix changes. The proposed NIR technique allows the scale-down studies needed for R&D of the elution process and enables the use of lab scale data to monitor the ionic exchange resin behaviour at pilot and industrial scales.