Tag Archives: particle analysis

Using Dynamic Imaging Particle Analysis to Characterise Biologics

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In recent years we have seen an increase in the role of biologics in medicine. Biologics are medicinal products that are created by biologic processes instead of chemical synthesis; these include products such as blood, vaccines, gene therapy, allergenics or somatic cells. Because of the increased role of biologics, the need to characterise particulate matter within those biologics has increased as well. In this article, we’ll take a look at how dynamic imaging particle size analysis is being used to characterise particulates in biologics, as well as some of the factors that need to be considered when using the technology.

The early days: Light Obscuration

In the early days of particle analysis in biologics, analysts used light obscuration techniques to attempt characterisation, but this method meant they faced a few hurdles. These were as follows:

The transparency of aggregated proteins

Biologics are subject to protein aggregation — that is, the formation of larger particles from a combination of smaller ones. Because aggregated proteins are transparent or “soft”, they are much tougher to detect than opaque particles, and light obscuration technology was not always able to detect them.

The amorphousness of aggregated proteins

The shape of the aggregates vary from circular to strand-like shapes. Light obscuration devices are capable of measuring size, but they assume that the particles are spherical in shape. Because aggregates could be absolutely any shape, many measurements were inaccurate.

The biologics are delivered through pre-filled syringes

This could result in silicone droplets being present, and might also result in inflated particle counts.

The introduction of Dynamic Imaging

A dynamic imaging particle size analyser, on the other hand, is capable of making various measurements even if the particle is transparent. It works by capturing digital microscopic images of biologic particles as they make their way through a flow cell. The result is a more detailed description of the particle and its shape, which also allows for analysts to recognise the difference between aggregates and silicone droplets.

Dynamic Imaging limitations

It would seem, then, that dynamic imaging has solved the problem of characterising biologics — but that’s not to say that the technology is perfect. In particular, there are three factors that analysts must consider whenever characterising biologics with the use of dynamic imaging. These are:

Resolution

Digital images don’t show the real world in the same way that the human eye does. Instead, images are pixelated, which means dynamic imaging systems can only count particles that are no smaller than 1µm, and can only differentiate shape for particles larger than 2-3µm. Electron microscopy is needed to measure particles smaller than these limits, but such a technique has many shortcomings of its own.

Colour threshold

Images are not only limited in size; they are also limited in their colour scale. Because imaging systems are backlit, particles in the optical path reduce the light that passes through to the camera sensor and, as such, the incoming pixel intensity becomes darker. This works fine for opaque particles, but not so well for the transparent protein aggregates. Additionally, the amorphous nature of the aggregates causes light to bend awkwardly around the structure, creating further confusion.

Image quality and sharpness

This great effects on the precision of particle measurements. The less sharp the image, the lower the accuracy when attempting biologic characterisation.

Finding a particle size analyser

Particle size analysers play a key role in biologics, so it’s important that you one you use is of a high quality and from a trusted supplier. ATA Scientific offers a range of quality particle size analysers perfect for characterising particulates in biologics. Contact us today for more information.

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4 Benefits of On-Line Particle Analysis for Mineral Processing

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In order to extract valuable minerals from naturally occurring ores, the process of comminution and milling must take place to produce materials of an appropriate particle size. This process is critical in order to ensure operating costs stay low and to ensure the minerals extracted are of high value. Traditionally, particle size analysis has been performed through manual measurement, but increasingly the industry is turning towards on-line particle size measurement methods such as laser diffraction. In this article, we’ll look at four reasons that laser diffraction is the optimum method for particle sizing in the mineral processing industries.

1. Quicker and higher ROI

Most studies have confirmed that return of investment for on-line laser diffraction occurs anywhere between six months and a year following installation. The biggest reason for this is that there is much less reliance on manpower; manual analysis methods generally necessitate highly-skilled individuals to be working around the clock, while on-line systems only require occasional intervention from a semi-skilled worker, lowering costs in terms of both time and expertise. These lowered man hours have the added benefit of minimising the risk of hazard material exposure.

2. Greater levels of process control

With off-line measurement, the frequency of analysis is quite low, occurring an average of once or twice an hour. This has the flow-on effect that operational changes are bound to be much less frequent; the operator will receive the data and make a change (perhaps a very large change), and won’t see the outcome of that change until the next analysis. With online particle size analysis, however, there is a constant flow of information, meaning that smaller changes can be made on a more consistent basis.  Additionally, the on-line method of measurement allows for a steadier stream of automated control. Both of these factors lead to more efficient process control.

3. Faster process optimisation

Since finding the optimal particle size is crucial to extracting the most valuable from the ore, the optimal processes must be put in place. Much like discussed above, off-line particle size analysis requires the analyst to wait until several samples have been taken and analysed before they can see the outcomes of their changes. With an on-line particle size analyser, however, this process is much quicker. Assessing new operating scenarios requires nothing more than a new steady state to be established, meaning the changes can be evaluated in minutes.

4. Immediate upset detection

The impact of an upset can be disastrous for the batch, leading to significant loss of profit. To avoid this kind of situation, it’s important to detect problems as soon as possible. With off-line particle size measurement, problems can go undetected for hours, but with on-line methods such as laser diffraction, there is constant monitoring of the process and upsets can be detected as they occur. Rio Tinto, for example, has enjoyed a two year period without unplanned stoppages, and it’s all thanks to their installation of an on-line particle size analyser. Problems are detected and the appropriate action is taken to remedy the situation before it escalates.