Nitrification inhibition using 2-chloro-6-(trichloromethyl) pyridine (TCMP) Add 10 mg TCMP/L to diluted sample or 3 mg TCMP to each 300-mL bottle or sample dilution vessel, or proportional amounts to other sized bottles, after initial sample dilution but before final filling of the bottles with dilution water Do not add TCMP to BOD bottles before they are at least two-thirds filled with diluted sample. (NoTE: TCMP dissolves slowly and can float on top of the sample if not mixed well)