Abstract
The experimental conditions of a semi‐micro COD determination procedure were investigated by means of a 24 factorial design in which the influence of temperature digestion time, dichromate concentration and catalyst concentration were evaluated. It was concluded that the temperature is the most significant variable, folowed by dichromate concentration, digestion time, and catalyst concentration in decreasing order of importance. Experimental conditions are recommended, which produce results that are not statistically different from those obtained with the standard reflux method.