Table 3.
Concentration factors and effective volume plated achieved by use of the BMFS ViroCap reusable filter housing (RH) and disposable filter housing (DH) with two volumes filtered (10 and 3 L) compared to a 0.5-L two-phase grab sample with 10 mL final concentrate volume
| Sample type | Volume filtered (v f, L) | Volume after primary concentration (v 1, mL) | Volume after secondary concentration (v 2, mL) | Volume assayed (v a, mL) | Primary concentration factor (c 1 = v f/v 1) | Secondary concentration factor (c 2 = v f/v 2) | Effective volume assayed (v e = v a × c 2, mL) |
|---|---|---|---|---|---|---|---|
| BMFS with RH | 10 | 200a | 10 | 3 | 50b | 1000 | 3000 |
| 3 | 200a | 10 | 3 | 15c | 300 | 900 | |
| BMFS with DH | 10 | 175 | 10 | 3 | 57.1 | 1000 | 3000 |
| 3 | 175 | 10 | 3 | 17.1 | 300 | 900 | |
| Two-phase grab sampled | 0.5 | 10 | N/A | 3 | 50 | N/A | 150e |
aVolume after double elution. When using a single elution, volume after primary concentration would be 100 mL. Regardless of volume after primary concentration, the volume after secondary concentration is 10 mL
bPrimary concentration factor after double elution. When using a single elution, primary concentration factor is 100 mL
cPrimary concentration factor after double elution. When using a single elution, primary concentration factor is 30 mL
dGrab sampling method followed by two-phase concentration method recommended for poliovirus sampling by the World Health Organization (WHO)
e v e = v a × c 1, as no secondary concentration is performed