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Basic calculation

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#1 Limpa

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Posted 10 June 2011 - 03:55 AM

Sorry for a very basic calculation.
I have a stock solution of 500 U per ul. I need the final solution to be 2000 U. I am going to add the stock in 6 ml of media to make it 2000 U. So, how much of the 500 U stock I need to put in the 6ml media?

#2 almost a doctor

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Posted 10 June 2011 - 04:45 AM

Sorry for a very basic calculation.
I have a stock solution of 500 U per ul. I need the final solution to be 2000 U. I am going to add the stock in 6 ml of media to make it 2000 U. So, how much of the 500 U stock I need to put in the 6ml media?

If your solution is 500U/ul and you need 2000U. You need 4ul of your stock no matter your final volume.

500U/ulx4ul = 2000U

edit: spelling mistake

Edited by almost a doctor, 10 June 2011 - 04:46 AM.

#3 Limpa

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Posted 10 June 2011 - 06:05 AM

Thanks. But my total concentration in 6 ml of media has to be 2000 Units of the solution. So, still I use 4 ul?

#4 GNANA

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Posted 10 June 2011 - 06:28 AM

Ofcourse YES.....

I always had an alternate hypothesis....

#5 pito

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Posted 10 June 2011 - 06:33 AM

Thanks. But my total concentration in 6 ml of media has to be 2000 Units of the solution. So, still I use 4 ul?

yes, but you dont add 4µl to 6ml ...

You had 4µl to (6ml-4µl, or 6000µl-4µl)
meaning you add 4µl to 5996µl to end up with 6000µl or 6ml in total.

Just to be 100% correct.

If you add the 4µl to 6ml, you end volume would be more then 6ml.

This is nitpicking and it might not be needed for your problem but it might be for other things you do in the future.

BTW: you say you need to have a final concentration of 2000 units... this is not a concentration....
A concentration means part per volume.. your end concentration would be: 2000units/6ml or 333.33333... units/ml

BTW I find it a very strange question you asked.
This is basic math... are you scared of making an error or insecure or? Or are you mixing up things like concentration and amount or?

Edited by pito, 10 June 2011 - 06:35 AM.

If you don't know it, then ask it! Better to ask and look foolish to some than not ask and stay stupid.

#6 Limpa

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Posted 10 June 2011 - 06:51 PM

Thanks guys. I got confused with the concentration. Yes, I was getting worried to make a mistake.

Thanks