Table 1.

Recovery of infectious H1N1 from large volumes of surface water using different filtration, elution, and PEG concentration conditions

Water sample	Level from factorial design	Parameter used for:								TCID50 recovered (%)
		Filtration		Elution				PEG concn
		Filtera	Flow rate (liters/h)	Buffer composition		Contact time (min)	Flow rate (liters/h)	Precipitation time (h)	Centrifugation time (h)	Eluate	PEG concentrate
				Beef extract (%)	Glycine (M)
A	1	Glass W	10	1.5	/b	10	30	O/Nc	2	2.3	1.2
	2	NanoC	10	3	0.05	10	30	O/N	1	<0.1	<0.1
	3	NanoC	10	1.5	/	10	10	2	1	<0.1	<0.1
	4	Glass W	10	3	0.05	10	10	2	2	1.0	0.3
	5	NanoC	30	1.5	/	5	30	O/N	1	0.9	<0.1
	6	Glass W	30	3	0.05	5	30	O/N	2	0.6	0.3
	7	Glass W	30	1.5	/	5	10	2	2	1.0	0.7
	8	NanoC	30	3	0.05	5	10	2	1	0.2	<0.1
B	9	Glass W	10	1.5	0.05	5	10	O/N	1	<0.1	0.1
	10	NanoC	10	3	/	5	10	O/N	2	0.8	<0.1
	11	NanoC	10	1.5	0.05	5	30	2	2	<0.1	<0.1
	12	Glass W	10	3	/	5	30	2	1	1.8	<0.1
	13	NanoC	30	1.5	0.05	10	10	O/N	2	0.1	<0.1
	14	Glass W	30	3	/	10	10	O/N	1	5.4	0.5
	15	Glass W	30	1.5	0.05	10	30	2	1	6.4	0.8
	16	NanoC	30	3	/	10	30	2	2	0.1	<0.1
C	1	Glass W	10	1.5	/	10	30	O/N	2	<0.1	<0.1
	2	NanoC	10	3	0.05	10	30	O/N	1	0.1	<0.1
	3	NanoC	10	1.5	/	10	10	2	1	<0.1	<0.1
	4	Glass W	10	3	0.05	10	10	2	2	4.1	1.0
	5	NanoC	30	1.5	/	5	30	O/N	1	0.2	<0.1
	6	Glass W	30	3	0.05	5	30	O/N	2	1.3	0.4
	7	Glass W	30	1.5	/	5	10	2	2	3.9	1.7
	8	NanoC	30	3	0.05	5	10	2	1	<0.1	0.1
D	9	Glass W	10	1.5	0.05	5	10	O/N	1	1.2	<0.1
	10	NanoC	10	3	/	5	10	O/N	2	<0.1	<0.1
	11	NanoC	10	1.5	0.05	5	30	2	2	0.1	<0.1
	12	Glass W	10	3	/	5	30	2	1	2.4	0.4
	13	NanoC	30	1.5	0.05	10	10	O/N	2	<0.1	<0.1
	14	Glass W	30	3	/	10	10	O/N	1	10.5	0.3
	15	Glass W	30	1.5	0.05	10	30	2	1	14.9	3.9
	16	NanoC	30	3	/	10	30	2	2	<0.1	<0.1

^aGlass W, glass wool filter; NanoC, NanoCeram filter.

^b/, without glycine.

^cO/N, overnight.