Table 3.
The probability of detecting SARS-CoV-2 RNA as determined using wastewater samples seeded with SARS-CoV-2, the adsorption extraction concentration method, and assayed using five RT-qPCR assays and one RT-dPCR assay. The % probability of detection was estimated using two probability models: exponential survival and the cumulative Gaussian models. The process limit of detection (PLOD) was defined as the concentration associated with a 95% probability of detection.
| % Probability of detection | Exponential survival model estimates of the SARS-CoV-2 concentration (GC/50 mL) | |||||
|---|---|---|---|---|---|---|
| US CDC N1 RT-qPCR | US CDC N2 RT-qPCR | CCDC N RT-qPCR | CCDC ORF1ab RT-qPCR | E_Sarbeco RT-qPCR | US CDC N1 RT-dPCR | |
| Model parameter ln (k) | -7.19 | -9.09 | -7.71 | -8.03 | -8.52 | -6.48 |
| 5% probability of detection | 68 | 457 | 113 | 157 | 258 | 33.4 |
| 25% probability of detection | 380 | 2563 | 639 | 880 | 1446 | 187 |
| 50% probability of detection | 915 | 6175 | 1539 | 2121 | 3484 | 452 |
| 75% probability of detection | 1829 | 12350 | 3078 | 4242 | 6969 | 902 |
| 95% (PLOD) | 3954 | 26689 | 6651 | 9167 | 15061 | 1952 |
| Cumulative Gaussian model estimates of the SARS-CoV-2 concentration (GC/50 mL) |
||||||
| Model parameter (μ) | 1188 | 10617 | 1886 | 2167 | 3266 | 448 |
| Model parameter (σ) | 1479 | 4940 | 1845 | 1083 | 2850 | 1533 |
| 50% probability of detection | 1188 | 10617 | 1886 | 2167 | 3266 | 448 |
| 95% (PLOD) | 3621 | 18743 | 4921 | 3948 | 7954 | 2970 |
CCDC: China CDC.