Chemical Oxygen Demand Formula

Equation for calculate chemical oxygen demand is,

COD = [(A - B × N × 8 × 1000)] / Volume of sample taken

Where,
A = Volume of Ferrous Ammonium Sulphate for blank
B = Volume of Ferrous Ammonium Sulphate for sample
N = Normality of Ferrous Ammonium Sulphate
V = Volume of sample