Particle Mysteries Take a Powder

Insights promise to enhance processing

By Seán Ottewell, Editor at Large

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In one project, the company carried out successful trials of an online particle size analyzer on an active pharmaceutical ingredient (API) milling operation at a commercial site of a major manufacturer.

Like many other API makers, the company used an iterative process that required numerous offline analyses of the milled powder to verify it met the correct product specification. Time consuming and wasteful, this procedure only can show that the properties of the batch are acceptable but reveal no information about manufacturing consistency.

Following the trials, the plant installed an Insitec online particle analyzer (Figure 3). This is linked to the mill's programmable logic controller (PLC) by an Insitec PC to provide a fully integrated system; Malvern software handles data exchange. The operator interacts with the PC via the mill's human machine interface and can input set points for the control loop, remotely start and stop the analyzer and mill, perform background tests, and receive particle size results.

The benefits of automating control include improved product quality, increased throughput and less waste — especially in the form of dust. Furthermore, automation opens up a route to semicontinuous operation and real-time release — important long-term goals in reaching operational excellence.

"This system has been used in many milling campaigns, some in excess of 20 tonnes, mate with consistent quality throughout. Together with streamlining operations and ensuring excellent quality, the embedded process analytical technology (PAT) also has enabled this company to reduce offline sampling — lab work — by an amount equivalent to 30% of its initial cost per campaign," says Alon Vaisman, Westborough, Mass.-based application development manager for Malvern.

As the technology moves from early adopters to more mainstream users, Vaisman notes that such PAT solutions are becoming very widespread in the chemical and other industries: "In my view this has become more of a requirement in the western market where competition is very aggressive and improving quality is a big driver. Whether you are talking about total quality manufacturing or Six Sigma, it's all about quality control."

In an effort to further improve its online automation, Malvern has launched specialized software to control the analyzer and peripherals, plus enable integration of the analytical data into the user's control system.

"In the future, I think that more of our work will focus on developing specialized software such as this in order to make integration easier," he adds.

Looking five years ahead, Vaisman believes the needs of the biopharmaceutical and nano sectors will spur new online analytical devices based on technologies now limited to the laboratory, and there will be a wider variety of online tools available than is currently the case. He also foresees traditional manufacturers responding to low-cost competition by opting for instrumentation that now might be considered too expensive or not designed for such processes, for example as used in the food industry, to boost efficiency.

"There will also be further improvements in the ease of process integration. PAT projects are expensive today in terms of equipment and validation. I hope that an increase in standardization will lead to easier integration and faster validation," he concludes.

Of course, laboratory-based analytical techniques will continue to play an important role at many sites far into the future. So, a major study about how the reliability of analytical instruments and the reproducibility of their results changes over time by Wyatt Technology, Santa Barbara, Calif., a maker of light-scattering instrumentation, should interest many plants. The company focused on results generated by two of its size exclusion chromatography-multi angle light scattering (SEC-MALS) instruments, which are widely used when investigating how particle size and distribution can vary from batch-to-batch in different processes. The company used data collected from an independent analytical laboratory over a five-year period, an unprecedented procedure for such instruments, it believes. "The findings… found extraordinary reproducibility from day-to-day, month-to-month, and year-to-year," says Wyatt.

Seán Ottewell is Chemical Processing's Editor at Large. You can e-mail him at


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