Becoming fully circular facilitated by PAT.

Process analytical technologies (PAT) have contributed to helping industrial processes become more efficient, more sustainable, safer, and more reliable for more than two decades. Real-time monitoring is the key to process control but also to process knowledge. Advancements in instrument performance and in the availability of complex data analysis methodologies have made PAT a fundamental pillar in quality by design concepts. On account of the 20th anniversary of the Arbeitskreis PAT of the GDCh, this article assembles use cases for and from PAT applications that do or will contribute to and impact relevant and forward-looking processes. Five examples are presented for the monitoring of sustainable processes from the recycling of industrial process water, solvents, and plastics, from biotechnological production using disposable reactors, i.e., single-use technology, and of product safety confirmation amenable to pharmaceutical production and real-time release. The applied PAT methodology illustrates use cases of online solid-phase extraction, ion-chromatography conductivity determination, mid- and near-infrared spectroscopy, and external cavity quantum cascade laser vibrational circular dichroism. The reviewed examples are taken to a perspective on future PAT developments.