How can I predict the percent qPCR signal due to contaminating DNA, for a given qPCR assay, and its matching NRT control?
Assuming 100% amplification efficiency, each step increase in Ct value represents a doubling in the amount of qPCR template. Therefore, evaluating the difference in Ct values between the qPCR assay, and its matching NRT control, leads to the following predictions:
|CtNRT - Ct+RT||Fraction of gene expression signal due to contaminating DNA||Percentage of gene expression signal due to contaminating DNA|
|1||(1/21) = 1/2||50%|
|2||(1/22) = 1/4||25%|
|3||(1/23) = 1/8||13%|
|4||(1/24) = 1/16||6%|
|5||(1/25) = 1/32||3%|