Methods to Quantitate Small Amounts of DNA

[billing at vetsci.microvet.arizona.edu]

This inquiry is for a colleague, so I may not have all the facts at my 
finger tips.  My colleague wants to use DS DNA as a substrate in a type 
of ELISA set up.  The question is, how much DNA from a known starting 
amount is bound?  Obviously, the unbound DNA is quantitated, but how?

I guess the best (most sensitive) method would be to use radio- or 
fluorochrome labeled DNA.  However, the new method is being set up to 
avoid using radioactivity and there is no fluorometer available.

I was thinking about maybe DIG labeled DNA, but there may be problems 
associated with the DIG interfering further down the line.  Anyone have 
any better ideas?  I think the amount of DNA would be in the 
nano-picogram range.

TIA

SJB