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dna concentration - please help (Jun/01/2009 )

hello,
please help. i have a 1000ng/ul stock dna, i need to get it down to 50ug in 100ul final volume. How do I do this or please give me the formula? thanks.

-biogirl1230-

c1*v1=c2*v2

Where c = concentration and v=volume, 1 and 2 are initial and final respectively.

-bob1-

bob1 on Jun 1 2009, 08:22 PM said:

c1*v1=c2*v2

Where c = concentration and v=volume, 1 and 2 are initial and final respectively.


a typo - the stock is 1000ug/ml, not 1000ng/ml

Is this right:

V1 = (50ug)*(0.100ml) / (1000ug/ml)

V1 = 0.005ml = 5ul of stock DNA + 95ul water

-biogirl1230-

Yes biogirl, that is correct.

-juanboja-

juanboja on Jun 2 2009, 05:03 PM said:

Yes biogirl, that is correct.


actually, that is not correct. I know this is an old post, but as I've just been redirected to it from another post about dilutions and concentrations, I thought I should reply and ammend the mistake as you guys are mixing conentrations with absolute amounts.

From biogirl1230, your stock DNA is at 1000ug/ml = 1mg/ml = 1g/l.

Now, you say you need 50g in 100l, which means your final concentration is 50g/100l = 0.5g/l. This is the concentration you have to use for C1V1=C2V2 so in this case: V1= (0.5g/l * 100l )/ 1g/l = 50l You need 50l of your stock solution + 50l of water. It's actually a simple 1:2 dilution.

A different way to look at it is: your solution is at 1g/l. you need 50g. Independently of your final volume you need 50l of this initial stock to have 50g, and whatever the final volume you need (in this case 100l) you top up with buffer (or water).

I know is late for whatever the experiement was, but hopefully this is of general help anyway.

-almost a doctor-

almost a doctor on Nov 2 2009, 08:50 PM said:

juanboja on Jun 2 2009, 05:03 PM said:

Yes biogirl, that is correct.


actually, that is not correct. I know this is an old post, but as I've just been redirected to it from another post about dilutions and concentrations, I thought I should reply and ammend the mistake as you guys are mixing conentrations with absolute amounts.

From biogirl1230, your stock DNA is at 1000ug/ml = 1mg/ml = 1g/l.

Now, you say you need 50g in 100l, which means your final concentration is 50g/100l = 0.5g/l. This is the concentration you have to use for C1V1=C2V2 so in this case: V1= (0.5g/l * 100l )/ 1g/l = 50l You need 50l of your stock solution + 50l of water. It's actually a simple 1:2 dilution.

A different way to look at it is: your solution is at 1g/l. you need 50g. Independently of your final volume you need 50l of this initial stock to have 50g, and whatever the final volume you need (in this case 100l) you top up with buffer (or water).

I know is late for whatever the experiement was, but hopefully this is of general help anyway.



Thats right 'almost a doc', I always go with the second way of doing it...
@ Biogirl1230, there was no typo in ur first post, 1000ng/ul and 1000ug/ml are both the same!!

-gogreen-