# Serial dilutions Watch

1. Hello there

I wonder if anyone may please be able to help me?

If I have made a dilution of a substance by adding 300ul of solute to 300ul solvent and then taking 300ul of this and adding it to a further 300ul of solvent - doing this until I get a dilution of 1:16 (therefore repeating the dilution 4 times), and I want to go from the concentration of the solute at 1:16 back to the original concentration of the solute when it was neat, what should I do? For example, if I find the concentration of the solute at 1:16 to be 0.40mg/ml, how would I know what the concentration was when it was neat (before dilutions) should I not have a sample of the neat version anymore? Do I need to multiply the concentration at 1:16, e.g. the 0.40mg/ml, by something?

Thank you very much.
2. 1:16 means your diluted sample is 16 times less concentrated than the original one. so if you multiply your concentration at 1:16 by 16 it should give you the original one. for example: 0.40X16= 6.4mg/ml
3. (Original post by alkyone)
1:16 means your diluted sample is 16 times less concentrated than the original one. so if you multiply your concentration at 1:16 by 16 it should give you the original one. for example: 0.40X16= 6.4mg/ml
Thank you so much!

Just to check, my dilution would be 1:16 if:

I add 300ul of solute and 300ul of solvent

then

I take 300ul of this and add it to 300ul of solvent

then

I take 300ul of this and add it to 300ul of solvent

then

I take 300ul of this and add it to 300ul of solvent

then

I take 300ul of this and add it to 300ul of solvent

4. I count 1 in 32 actually.
1/2 to the power of 5 (you halve the concentration five times).

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Updated: April 27, 2016
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