TABLE 4.

Presence of PCR Inhibitors Assessed by qPCR

Samples	Qv			Qm			iG			Ab
	Cq mean undil	Cq mean 10-fold dil	ΔCq mean (10-fold dil-undil)	Cq mean undil	Cq mean 10-fold dil	ΔCq mean (10-fold dil-undil)	Cq mean undil	Cq mean 10-fold dil	ΔCq mean (10-fold dil-undil)	Cq mean undil	Cq mean 10-fold dil	ΔCq mean (10-fold dil-undil)
1	23.4	26.4	3.1	24.2	24.1	−0.1	22.5	24.2	1.7	29.3	25.0	−4.3
2	25.5	28.2	2.8	32.2	27.3	−4.9	24.5	25.6	1.1	31.0	31.0	0.0
3	23.8	26.8	3.0	24.1	25.4	1.3	27.3	27.9	0.6	30.5	30.3	−0.2
4	27.5	30.2	2.8	30.2	29.9	−0.4	29.9	28.7	−1.1	37.3	36.9	−0.5
5	28.6	32.3	3.8	27.6	30.9	3.2	28.4	30.9	2.5	37.2	37.0	−0.2
6	28.2	30.2	2.0	26.9	29.6	2.8	29.0	29.4	0.4	35.4	35.1	−0.3
No. of inhibited samples	1/6			4/6			6/6			6/6

Theoretical change in comparative threshold (ΔCq; Cq 10-fold diluted sample − Cq undiluted sample) = 3.3. There is no inhibition if ΔCq experimental (Cq 10-fold diluted sample − Cq undiluted sample) = 3.3 (±0.5). Inhibited qPCR reactions are indicated in bold italic. Negative ΔCq indicates a strong inhibition. undil, Undiluted DNA sample; dil, diluted sample.