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stock concentration and working concentration

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#1 Limpa

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Posted 21 February 2011 - 02:46 PM

If I have a powdered reagent and it says on the bottle that is 5mg. Now I want to dissolve that solution in 200 ul pbs (for example) for my experiment at a concentration of 100 ug, what we do then?
P.S. mol weight of the reagent is 1774.9

#2 bob1

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Posted 21 February 2011 - 03:22 PM

100 ug per what? if you don't define the units it is pretty hard to answer your question.

5 mg = 5000 ug - if you dissolve this in 200 ul PBS you will 25 ug/ul or 25 mg/ml, you cannot get anything 100 ug out of this, unless you want to take 100 ug - in which case it is 4 ul. (c= n/v is helpful here!)

What concentration do you want for your final concentration?

#3 claritylight

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Posted 21 February 2011 - 05:39 PM

100 ug per what? if you don't define the units it is pretty hard to answer your question.

5 mg = 5000 ug - if you dissolve this in 200 ul PBS you will 25 ug/ul or 25 mg/ml, you cannot get anything 100 ug out of this, unless you want to take 100 ug - in which case it is 4 ul. (c= n/v is helpful here!)

What concentration do you want for your final concentration?

what is c = n/v, can you please explain it out? thanks

#4 pito

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Posted 22 February 2011 - 12:41 AM

100 ug per what? if you don't define the units it is pretty hard to answer your question.

5 mg = 5000 ug - if you dissolve this in 200 ul PBS you will 25 ug/ul or 25 mg/ml, you cannot get anything 100 ug out of this, unless you want to take 100 ug - in which case it is 4 ul. (c= n/v is helpful here!)

What concentration do you want for your final concentration?

what is c = n/v, can you please explain it out? thanks

C is nothing more then the concentration, thus c = #moles (n) / volume (v).

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

#5 bob1

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Posted 22 February 2011 - 04:24 PM

Yeah, that is the usual use, however, in the case of many things biology, c= concentration, n= the number of whatever you want (weight, total number of cells, etc.) and v=volume.

#6 pito

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Posted 23 February 2011 - 06:06 AM

Yeah, that is the usual use, however, in the case of many things biology, c= concentration, n= the number of whatever you want (weight, total number of cells, etc.) and v=volume.

Indeed, n can mean anything really.. its just what you have in your "volume".

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