Tunable diode laser-absorption spectroscopy (TDLAS) can provide the advantages of continuous process control of pharmaceutical drying to manufacturers using water as their primary solvent. Pharmaceutical quality control requires that the drying process be stopped periodically and samples removed for loss on drying (LOD) analysis. If the product is not dry, the process is restarted and allowed to run for an indeterminate period. This time-consuming process is repeated until the LOD achieves a predetermined value. The TDLAS technology serves as a time-saving procedure to determine dryer end-point. The continuous real-time monitoring can pinpoint the exact moment when a product has dried as much as possible. This determination then is confirmed by LOD analysis, eliminating numerous stops and re-starts of the drying process. The trial demonstrated that TDLAS techniques could be used to continuously monitor and control the solvent drying process online, in real time, without operator intervention or process interruption.
Ametek Process Instruments