concentration of oligomers

[Lisa Vawter]

Hi all.  When I make primers, I measure the absorbance and calculate
the number of nmoles I have.  Sometimes someone gives me primers and 
tells me how much I've got in micrograms.  I've seen several quick 
and dirty equations for going back and forth, usually incorporating
some sort of average molecular weight for a nucleotide and the number
of nucledotides in the oligo.  What equation do you use?  How 
accurate do you feel you need to be in estimating primer concentrations
for regular old boring ABI sequencing of PCR products?  Lisa Vawter
vawter at green.harvard.edu