Karl Fisher Reagent

Dissolve 762 g of iodine in 2,420 ml of pyridine in a 10 liter glass stoppered bottle, and add 6 liters of methanol. To prepare the active stock, add 3 liter of the foregoing stock to a 4 liter bottle, cool in ice bath. Add carefully 135 ml of liquid sulfur dioxide, collected in a calibrated cold trap,and stopper the bottle. Shake the mixture until homogeneous, and set aside for one or two days before use.