Effect of PEC on PCR specificity and sensitivity. A: The impact of PEC on PCR specificity was assessed by directly amplification of the HRES1 target from blood samples in the absence (W/O) or presence (W/W) of the enhancer; 1.3 mol/L of betaine was included for comparison. The blood sample was serially fivefold diluted from 4 to 0.00001% (final concentration in PCR, lanes 1 to 9), and the negative control contained no DNA or blood (N). A 488-bp HRES1 target (GC content is 81%) was amplified from different concentrations of blood sample. OT, OmniTaq; OKT, Omni Klentaq. B: PCR sensitivity in the blood sample was also evaluated by amplification of the same target from both purified DNA and blood. The blood sample was serially fivefold diluted from 4 to 0.00001% (final concentration in PCR, lanes 1 to 9), and a 488-bp HRES1 target was amplified both from purified DNA and blood containing the same amount of DNA in presence of PEC. The negative control contained no DNA or blood (N). PCR products were resolved in a 1.5% agarose gel. Lanes M, DNA standards ladder.