Moving to semi-continuous impurity removal using silica-based disposable cartridges has allowed AstraZeneca to increase throughput at its pilot plant while improving other areas of operation.
“Efficiency in metal reduction as high as 98 per cent has been so far achieved at tens of kilograms scale”, researchers at AstraZeneca and PhosphonicS write in the journal Organic Process Research & Development.
The journal article describes how practices at the pilot plant in Loughborough, UK evolved from 2007 to 2010. Over this period AstraZeneca moved from adding absorbent to batch reaction vessels, to pumping the mixture through a multi-cartridge filter.
Use of cartridges has led to time savings. “One of the major benefits of this procedure appeared to be the time savings: the iridium removal procedure took around 4 hours (for a 400kg batch)”, the researchers write. However, the process may be unsuitable for some for some tasks.
“It is important to stress that no single technique will fit all metal removal requirements. Many will suffer from severe disadvantages including a lack of generality and reproducibility, product loss and an inability to reach regulatory or process step acceptable levels of metal”, the researchers write.
Economics & environment
The economics of using scavenger cartridges are only touched on in the paper but areas that must be considered are pointed out. For example, while use of cartridges could be seen as an extra material cost, the researchers note there are longer-term benefits to using the more efficient system.
Environmental gains have also been realised. “From the early studies carried out in our laboratories and pilot plant, the optimisation of the scavenger process has led to a remarkable reduction of the scavenger loading and a reduction of solvent usage for cleaning purposes”, the researchers write.