Hi, I have a problem with positive non-template control (NTC). In some of my PCR systems I have the Cp of NTC only 1 cycle later than a regular sample! In some other systems the difference is 2 or 5 cycles. This is bad because it suggests massive contamination. Nevertheless, I have realized that dRn of the contaminated NTC samples is much much lower (10times or more) than the dRn of regular sample. I do not understand what is going on in this system, but I am convinced there may be a chance to work with it somehow in spite of that “contaminated NTC”, or even to somehow take advantage of this phenomenon (massively decreased fluorescence signal) in comparison with regular (positive) sample. I would appreciate any suggestion. What does mean strong positive signal in NTC with very weak fluorescence?
Thank you! Paja