Quantitative PCR fine tuning

[Robert Passey]

Hi,

I am trying to distinguish between +/- and -/- DNA samples but am having
trouble with a small amount of contaminating +/- DNA in my -/- samples.
As little as 1/20 th contamination is causing problems.

I am using a standard approach where the PCR reaction is still in log
phase but the contaminating product seems to have caught up with the
"main" product by the time I can see bands.

Does anyone have any ideas on how I can either slow down the
contaminating product or speed up the other?

Thanks,

Rob Passey