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Resuspending primers calculation - (Jul/11/2013 )

I'm having problems trying to understand de chemestry in resuspending primers. I know I can use online calculators, and I have the general formula like multiply the initial (dry) concentration x10 and get a final concentration of 100 ul/L or

"convert from nmole to umole then divide by the desired concentration in umole/L. The umoles cancel out giving the needed volume in liters. We then convert liters to ml."
Still my question is the initial concentration wich comes in nm is nm/L or nm/?? Because molarity is always expressed for a volume of solution. Then when we divide we are not dividing only nm but nm/some volume

Please help I'm an anthropologist so this part of work is hard for me. Sorry for my english!
Thank you in advance,
Patricia

-Paty-

Usually primers (oligos) come in lyphilized powder with the amount (mass) indicated on the tube, for example, 4.9 nmol. We usually reconstitute the primer to make a 100 uM/L stock solution, we will need to add 49 ul TE buffer to the tube (4.9 nM/49 ul = 100 um/L). So if you know the amount of the primer from the tube, it is easy to determine how much solvent is needed without any calculation.

To put it in a simple way, if you have x nmol dry weight primer, you add 10 * x ul TE buffer, you will obtain 100 uM/L solution.

-pcrman-

be careful with nomenclature. uM=umol/L. uM/L is, at best, redundant, at worst, meaningless.

-mdfenko-

Thank you very much for your answers. My confusion is with nomenclature indeed. 

-Paty-

We multiply nmol of primers by 50 to find the micro liter of water that should be added to them.

 

for example:

primer GAPDH-F  nMol is  20

so multiply it by 50=>  20*50= 1000

now add  1000 microlitter of clean water to it and mix.

now 1micro litter is enough for 10 to 50 micro litter of  pcr reaction.

-memari-