CAN/CGSB-9.2 No. 4-94

1.1 This method of measuring colour can be applied to sulphate (kraft) and sulphite pulp mill effluents, providing their colours closely match the colour of the standard platinum-cobalt solution. The method cannot be applied to effluents of unusual colour, i.e., to dyed solutions. 1.2 The colur of an effluent is expressed in arbitrary colour units. One colour unit (C.U.) is equivalent to the absorption of light at the wavelength of 465 nm by 1 mg/L of platinum in the platinum-cobalt standard solution.