. 2021 Jun 11;87(13):e00433-21. doi: 10.1128/AEM.00433-21

TABLE 1.

C_T values for preliminary samples from hospital cleanout valve and the local municipal WWTP, processed using various concentration and extraction methods from literature^a

Source	Extraction	C_T value
		EP filtration			Ultracentrifugation			PEG precipitation			Biobot PEG			No concn
		N1	N2	RP	N1	N2	RP	N1	N2	RP	N1	N2	RP	N1	N2	RP
Hospital	None	31.2	32.8	33.3
	QiaAmp without DTT	33.4	33.2	ND^b	33.3	39.9	35.3	ND	35.2	ND	ND	ND	ND
	QiaAmp with DTT^c				36.5	34.7	32.6
	NucleoSpin	28.9	29.5	31.0	30.9	32.5	30.1	31.4	31.3	ND*	36.7	37.1	35.1
WWTP raw influent	QiaAmp without DTT				ND	ND	34.4	35.5	ND	ND	ND	ND	ND
	QiaAmp with DTT^c				38.2	ND	32.9
	NucleoSpin				30.3	31.2	28.3	33.7	32.5	33.3	ND	ND	ND
WWTP primary solids	QiaAmp without DTT													36.2	ND	ND
	QiaAmp with DTT^c													34.7	36.2	40.1
	NucleoSpin													31.8	32.5	34.6

All methods were applied to subsamples of a composite sample collected on a single day in early July 2020 and processed the same day. Boldface indicates positive determinations. Blank cells correspond to combinations of protocols that were not assessed. ND, not detected (C_T ≥ 45).

Sample inhibition occurred, but the sample was positive for the presence of SARS-CoV-2 RNA.

Postextraction treatment with DTT prior to qPCR.