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# Diluting DNA

### #1 dorts

dorts

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Posted 26 May 2009 - 07:13 AM

This may seem like quite a basic question but I always need clarification on any dilutions I do.

I have undiluted DNA samples and I know the concentration (ng/ul) of each of the samples but I need to dilute them for analysis to between 5-15 ng/ul. Cant remember what solution they mentioned that I will be using for dilution though the question I am asking doesnt really depend on that.

What I need clarified is how I work out how much of the original undiluted DNA sample I need to add to the soln to make it up to the right concentration range. For example, if I have a DNA sample of 1000 ng/ul, how do I work out what volume of this to add to the soln to make its concentration 5-15 ng/ul?

Hopefully I havent confused you all with my wording, thanks in advnace for any help!

Edited by dorts, 26 May 2009 - 07:13 AM.

### #2 almost a doctor

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Posted 26 May 2009 - 08:04 AM

dorts, on May 26 2009, 04:13 PM, said:

This may seem like quite a basic question but I always need clarification on any dilutions I do.

I have undiluted DNA samples and I know the concentration (ng/ul) of each of the samples but I need to dilute them for analysis to between 5-15 ng/ul. Cant remember what solution they mentioned that I will be using for dilution though the question I am asking doesnt really depend on that.

What I need clarified is how I work out how much of the original undiluted DNA sample I need to add to the soln to make it up to the right concentration range. For example, if I have a DNA sample of 1000 ng/ul, how do I work out what volume of this to add to the soln to make its concentration 5-15 ng/ul?

Hopefully I havent confused you all with my wording, thanks in advnace for any help!

always refer to the basics for dilutions:  C1*V1=C2*V2
C1: initial concentration
V1: the volume of  C1 you need to make C2
C2: the final concentration you want to make your solution at
V2: the final volume

So you need to add a volume of:  V1=C2*V2/C1

Also remember that  V2=V1 +Vd (vd: volume of diluent you need to add to V1 to make up V2).

Hope this helps