Investigating Sea Water

Investigating sea waterToday my research on the Beckman Coulter website has turned up some useful application notes on using a Coulter Counter to count and size particles and cells in sea water. You can find and download the document yourself by visiting the site, clicking on the appropriate product area and then choosing ‘Literature’ in the right-hand column.

While many people associate the Coulter Counter most closely with blood counts, the Coulter Principle – or ‘aperture technology’ as it is sometimes described – can be turned to counting and measuring all manner of particles in liquids.

Ocean and environmental scientists have long used Coulter Counters in their research and monitoring work. In the application described by these notes, the instrument used was a Multisizer 3 from Beckman Coulter. Its key advantages over equipment using other techniques include its speed, ease and accuracy, and the fact that it will count and measure particles and cells, automatically, regardless of their number. Importantly, the results obtained are unaffected by the skill and judgement of the user – which cannot be said for manual methods.

I will leave you to look up the details of how to set up and calibrate the Coulter Counter, and of the procedure to follow, but these are explained very clearly in the notes.

Results obtained using the described procedure are shown in terms of algal cells counted per millilitre. Size distribution is plotted in a graph. As well as determining the total cell concentration, the instrument’s software has an Interpolation Points function which allows cell concentration to be measured at size levels pre-set by the user.

The account of this procedure and its results concludes that Coulter Counter technology will produce the best possible resolution when it comes to counting cells and particles. As such, it is highly recommended for particle characterisation in oceanography and environmental science.

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