This part of ISO 8968.IDF 20 specifies a method for the determination of the nitrogen content of liquid, whole or skimmed milk.It concerns a semi-micro rapid routine method following the block-digestion principle.NOTE The method is a more rapid method than that described in ISO 8968-1.IDF 20-1 and ISO 8968-2.IDF 20-2 since the digestion time is reduced by taking a lower mass of test portion and using hydrogen peroxide together with sulfuric acid and a catalyst in the digestion.