Your samples may contain PCR inhibitors


RNA that contains inhibitory compounds (e.g., sample preparation reagents, excessive protein) can lead to partial or complete inhibition of downstream PCR. PCR inhibitors originating from the starting material include heparin (>0.15mg/mL), proteins such as hemoglobin (>1mg/mL), polysaccharides, chlorophylls, melanin, humic acids, etc. Contaminants from the nucleic acid extraction phase include SDS (>0.01% w/v), phenol (>0.2% w/v), ethanol (>1%), proteinase K, guanidinium, and sodium acetate (>5mM).

How to identify PCR inhibition