Do you have the mole amount? if so you can use C = n/v or rearranged for you, V = C*n

Then check by spectrophotometry.

Does that make sense?

Steve

No, Steve! I haven't made sense... At first, I don't know mole amount. Than what is C (concentration????) and n?

Hi Alexandra

The calculations looks fine for ...making a oligo solution of 100 µM or (100 picomoles/microlitre)

C = concentration, n = moles

I haven't seen your way of doing it... however you could do it this way...

1 OD = ~ 33ug .... so 7 OD = ~ 231 ug

n=m/Mw

231x10^-6/7029 = 32.86nmoles

=> 328.6 ul water...

Alexandra, if you were the one who bought the primer you should have received a specification sheet for it. It states how much primer (usually in mg) you have. Knowing the amount of the primer and its molecular weight, you just need to do some simple calculations to get the volume of water it needs to be diluted in to get your desired concentration. If, however, you don't have that specification sheet, I would recommend contacting the manufacturer's technical support. These people are very helpful and can even do the calculations for you. For primers 1 OD unit (A260) usually equals to 20-30 ug/ml (it depends on the primer's length and how many of each base it contains).

Stephen's calculations are closest to your desired but you won't know for sure what the concentration is unless you check it using spectrophotometry.

I also agree with Agniezka...if you have a product data sheet from the company...it would be simple and straightforward

Dear friends! The company pointed only 4 parameteres: quantity (OE), Mol.weight, length and T melting. That's all! The company beleive me to calculate everything without any problems!!!

Just follow my suggestion, then you can check the exact concentration using a spectrophotometer. The company never sends you the amount they tell you they do anyways, so its always good to double check with a spec.

Thanks a lot, Stephen!