Multisizer 3 Coulter Counter – Further Advantages

Coulter Counter - Multisizer 3

In my last post I gave a summary of the capabilities of the Multisizer 3 Coulter Counter from Beckman Coulter, but there was a lot more that I could have told you. For full advice on which Coulter Counter is best for your particular application, and why, you should talk to Meritics. In the meantime, I would like to tell you just a little more about what the Multisizer 3 can do.

In the study of such processes as cell growth, cycles and death, osmotic stress compensation, pathogenesis and phagocytosis, it is important to be able to measure changes in cell size and volume (including mean cell volume or MCV). The Multisizer 3 can do this, even if the changes happen over as little as a few seconds or hours. Using the instrument’s Overlay function, cell size in populations can be readily visualised and compared.

Bacterial cells have a tendency to aggregate, which can reduce the effect of antimicrobial agents on them. To reduce aggregation, a combination of filters and detergents can be applied to the bacteria. Researchers wishing to assess the relative proportions of single cells and aggregated clumps in a sample can use two different apertures in the Coulter Counter. With its Multi-Tube Overlap feature, the Multisizer 3 can then create a single, continuous size distribution by merging the results obtained.

Moving away from cell studies to the contamination of liquids by insoluble materials, the Multisizer 3 has a lot to offer laboratories monitoring purification processes. The concentration of such solids is normally too low to be characterised by other technologies but the high sensitivity of the Coulter Counter makes it possible.

A particular application of the Multisizer 3 is in assessing solid contaminants in hydraulic fluids and lubricants. The ISO Solid Contaminant Code for Hydraulic Fluids and Lubricants defines contamination in terms of the number of particles above a specific size in a sample. Using the Multisizer 3’s Size Interpolation function, size data can be arranged in reports according to the specified boundaries.

When characterising powders, it is traditional to express volume % size distribution, rather than number % size distribution, as this gives comparable results to the older sieve technology. A problem arises if the size distribution is not Gaussian, as volume % will not show up the fine particles of the main population. In cases where these fine particles might have an effect on product or process quality, the ability of the Multisizer 3 to measure both volume % and number % size distributions is crucial.

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