Another way that particle characterization can benefit process development is through simulation, which involves using characterization
data to construct mathematical models that predict process performance. These models, if robust, can be used to conduct virtual
"The big attraction of process simulation is that it allows virtual experimentation, which is cheaper and quicker than the
laboratory or pilot scale equivalent," explains Kippax. "The drawback is the effort required to develop a reliable model."
Despite this, however, Kippax added that he expects process simulation to become more widely used within in the industry in
the coming years because of the potential it has for aiding scale up and troubleshooting.
Particle characterization has come a long way from its early days, but there is always room for more progress. "The next
major development in particle sizing is likely to be in measuring in three dimensions," says Rideal. "Computer technology
will be a driving force where the current impressive computer graphics from the film industry will be incorporated into particle
sizing. There is also a move to borrow technology from the medical world, so expect to see X-ray CAT scans and MRI instruments
appearing in the particle-metrology laboratory."
Meanwhile, Kippax is hopeful that there will be more advances in laser diffraction. "One goal is to make the performance gains
already made more universally accessible. Greater embedded support during method development and throughout the measurement
process, for example, would ensure that even inexperienced users could fully exploit the technology."
With such improvements on the horizon, industry's main challenge may not stem from technology, but rather from the skill of
the operator using it. "Just because an instrument costs in excess of $100000 does not mean that the results are any better
than using a sieve costing £100," says Rideal. "The old adage of 'rubbish in, rubbish out' has never been so relevant."
1. ICH, Q6A Specifications: Test Procedures and Acceptance Criteria for New Drug Products: Chemical Substances (May 2000).