| Sample No. | Water sample | Cl−/ (mg・L−1) | Dilution fold | Unspiked COD/ (mg・L−1) | Spiked COD/ (mg・L−1) | Spiked recovery/% |
| 1 | JHSX | 92,744.4 | 10 | 154.1 | 631.1 | 95.4 |
| 2 | JHCL | 74,155.4 | 10 | 150.5 | 630.3 | 96.0 |
| 3 | XJ81J | 7578.5 | 10 | 109.0 | 641.3 | 106.5 |
| 4 | XJ81C | 7699.7 | 10 | 148.2 | 635.0 | 97.4 |
| 5 | XJ91J | 2086.8 | 10 | 123.1 | 626.8 | 100.7 |
| 6 | XJ91C | 2273.0 | 10 | 87.8 | 606.8 | 103.8 |