Feb 24, 2021 · The analyses were based on the HACH vial high range (20 mg/L to 1500 mg/L) Method 8000 for COD and Ammonia Test ‘N Tube vials salicylate method high range Method 10031 (0.4 mg/L to 50.0 mg/L) for AN (HACH Company 2019). The pH of the batch experiment was monitored using a pH probe, Eutech pH300.