Analysis of powder phenomena inside a Fette 3090 feed frame using in-line NIR spectroscopy

•Differences in spectra baseline are affected by mass hold-up and paddle wheel speed.•Powder wave behavior due to paddle movement.•Differences on the NIR prediction due to changes in powder dynamics.•NIR spectroscopy can be assessed the blend uniformity during the die filling process.•NIR can be a development tool for in-line monitoring of powder during die filling. New analytical methods are needed to understand and optimize the processes by which tablets are produced. Fette 3090 tablet presses are commonly used in the pharmaceutical industry. A near-infrared (NIR) probe was installed into a Fette 3090 feed frame to understand and monitor the die filling process. The second objective was to analyze in detail the different factors that could affect the prediction of the developed NIR calibration models. Two monitoring positions for NIR spectrometers were evaluated; one at each side of the feed frame. A powder wave behavior caused by the paddle motion was observed inside the feed frame. The study also revealed that NIR spectra can help in the understanding of powder flow inside the feed frame. It was demonstrated that NIR spectra baselines can also be used to determine changes in mass inside the feed frame. The new NIR method showed that the paddle wheel speed has a significant impact in the powder dynamics inside the feed frame. The baselines of the NIR spectra depended on the mass hold-up inside the feed frame and paddle wheel speed. Studies using blends were performed to develop a NIR calibration model based on the feed frame system dynamics to determine acetaminophen drug concentration variability during the die filling process. The study found that variation in the distance from the powder to the probe due to paddle wheel speed has a significant effect on the NIR prediction. This study found that with NIR spectroscopy, blend uniformity can be assessed with high accuracy during the die filling process using the corresponding paddle wheel speed in-line calibration model. NIR was demonstrated to be a good development tool for the in-line monitoring of powder during the die filling process.