TABLE 1.

Geometric mean recoveries and geometric standard deviations of PV and PV RNA spiked into samples determined by RT-qPCR

Sample	Sample type	Spiked PV viriona				Spiked PV RNAb (nondilution)
		Nondilution		100-fold dilution
		GMc (%)	GSDc	GM (%)	GSD	GM (%)	GSD
Blank (Milli-Q)	Raw	100	0.08
	Filt	67	0.04
	Acid	70	0.05
	Conc	100	0.03
Wa-HA	Raw	0.030	0.14	56	0.05
	Filt	91	0.18
	Acid	106	0.08
	Conc	0.10	0.39	33	0.44
Ald-HA	Raw	<0.0001d		53	0.28
	Filt	110	0.17
	Acid	130	0.26
	Conc	0.00078	0.14	73	0.05
IH-HA	Raw	130	0.26			<0.0001	-
	Filt	150	0.19			5.2	0.22
	Acid	160	0.14
	Conc	130	0.24
R1	Raw	89
	Conc	9.9		62
R2	Raw	140
	Conc	<0.0001		150
R3	Raw	110
	Conc	<0.0001		77

^aPV virions were spiked into the samples just before the RNA extraction step.

^bExtracted PV RNA was spiked into the samples to a final concentration of 4.5 × 10⁴ GC/μl and quantified without an RNA extraction step.

^cGM and GSD, geometric mean and geometric standard deviation, respectively (n = 3 for blank and humic acid samples; n = 1 for river water samples; GSD for river water samples cannot be shown).

^d<0.0001% indicates that spiked PV or PV RNA was not detected by RT-qPCR.