Progress with Solids Takes Shape

Improvements in particle characterization bolster processing.

By Seán Ottewell, Editor at Large

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For Malvern, however, the future lies in online measurement.

"In terms of technologies, we are seeing laser diffraction becoming more widespread as a QC method. The question then is can we make this online?" notes Paul Kippax, product manager, diffraction products.

This has been done for more than 10 years with dry powders, he points out, but liquid flows such as suspensions and slurries present more of a challenge — although the company's Mastersizer technology can handle both in the lab. "We have developed a dilution system which extracts a sample from the process, dilutes it and then measures it by laser diffraction. Our focus now is on understanding when dilution is required and how to better control the dilution process to account for sample stability, process temperature changes and to account for the measurement requirements for laser diffraction measurements. Within the process sector, liquids represent the most rapidly growing market," says Kippax.

Within lab applications, there's also increasing focus on particle shape, which is very important in many applications such as foreign particle analysis and agglomerate/floc detection. "Here we have the FPIA 3000 for wet dispersions and the Morphologi G3 for dry dispersion; these systems are finding applications with R&D and also for root-cause analysis."

There's also a big move to nanoscale applications, for which Malvern's solution is the Zetasizer range based on dynamic light scattering/photon correlation spectroscopy (Figure 2).

The irony here is this is the first technology developed by the company back in the late 1960s and early 1970s. Dynamic light scattering systems are finding application in development of colloidal products — including sunscreens, ink jet pigments, ceramics and catalysts — where particle size typically is under 100 nm. However, the company's fastest-growing market relates to characterization of biopharmaceuticals such as proteins and peptides, particularly within academia.

"As interest continues to grow within these applications, a big challenge is to develop an online sampling system that can handle these materials. The current measurement technique (dynamic light scattering) relies on measuring the speed of Brownian motion of particles (their diffusion rate) — this is then used to calculate their hydrodynamic radius. Measurements are made in a batch measurement cell, where the sample does not flow. For process measurements the challenge will be to make measurements with flowing samples. Is an in-flow technique possible?" he wonders. The company now is investigating this. "Through this we hope to be able to meet the challenges associated with sample presentation and maintaining a barrier between the process and the measurement device as well," explains Kippax.

Other Technologies
X- Ray-fluorescence-based instrumentation also will see wider use, hopes Thermo Fisher Scientific, Ecublens, Switzerland.

The company primarily focuses on lab instruments, although some can be used in-line in specific applications such as cement manufacturing. "At the moment, organic chemicals are too complex for this technique," says Robert Hergenrader, manager, petrochemicals and analytical service labs/bulk elemental analysis. "In 10 years' time it would be great for X-ray technology to be available for on-line use. If we can get beyond the technical hurdles it would be a big leap forwards. At the moment, X-Ray systems are considered quite expensive and placed in middle to upper cost for process control equipment. But we are always looking for way to improve value to our customers," he adds.

Meanwhile, Fluid Imaging Technologies, Yarmouth, Maine, is expanding its line of FlowCAM products. These combine the capabilities of flow cytometry and microscopy and reportedly provide an order of magnitude improvement over each. The company has added the FlowCAM V-1000, an economical application-specific system with a small footprint. It suits duties, e.g., in QC labs, in which similar types of sample are continually run.


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

 

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