This International Standard specifies a reference method for the determination of the copper content of milk and milk products. The method is applicable to a) milk, skimmed milk and buttermilk, b) evaporated milk and sweetened condensed milk, c) whole and skimmed milk powder, d) cream and butter, e) butterfat, f) ice-cream, g) hard, semi-hard and soft cheeses of various ages, and processed cheese, and h)caseins, caseinates and coprecipitates. The method is suitable for determining copper contents as low as 0,05 mg/kg in test samples of butter and butterfat. NOTE See IDF 68 for details of butterfat.