Serial Dilutions « Richmondschoolbiology’s Weblog

These are used a lot in biology and our syllabus requires us to know how to do them. They allow us to dilute a stock solution in small steps rather than in one giant leap. This means that instead of measuring a very small volume of the stock solution (which is prone to errors) we can use larger volumes. This improves the accuracy of the resulting solutions. It is also faster than making up each concentration separately from scratch.

A common dilution is 10x – we take 1ml of the stock solution and add 9 ml of distilled water to dilute by a factor of 10; this is repeated with the newly produced solution in place of the stock to produce a further x10 dilution. If our orignial stock solution was 1M then the dilutions would be 0.1M, 0.01M etc. This is shown in the diagram below:

You can read more about this on the SAPS website and watch a you tube video clip.

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