# Serial dilutions

Announcements Posted on
Four hours left to win £100 of Amazon vouchers!! Don't miss out! Take our short survey to enter 24-10-2016
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).

## Register

Thanks for posting! You just need to create an account in order to submit the post
1. this can't be left blank
2. this can't be left blank
3. this can't be left blank

6 characters or longer with both numbers and letters is safer

4. this can't be left empty
1. Oops, you need to agree to our Ts&Cs to register

Updated: April 27, 2016
TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Today on TSR

### Who is getting a uni offer this half term?

Find out which unis are hot off the mark here

### How to get a 1st class degree

Poll
Useful resources
Study resources

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.