Patent ID: 8399211

Claim:
A process for preparing a pharmaceutical product containing a mixture of polypeptides, each of which consists essentially of alanine, glutamic acid, tyrosine and lysine, which process comprises the steps of obtaining a batch of a mixture of polypeptides, each of which polypeptides consists essentially of alanine, glutamic acid, tyrosine and lysine; performing molecular weight sizing chromatography on a molecular weight sizing column to determine average molecular weight of the batch of the mixture, wherein the molecular weight sizing column is calibrated by using a plurality of molecular weight markers to establish a relationship between retention time of the molecular weight markers on the molecular weight sizing column and molecular weight of the molecular weight markers, wherein each of the molecular weight markers is a polypeptide consisting essentially of alanine, glutamic acid, tyrosine and lysine, wherein in the molecular weight markers the molar fraction of alanine is 0.42 to 0.45, of glutamic acid is 0.13 to 0.15, of tyrosine is 0.08 to 0.10 and of lysine is 0.3 to 0.4; and certifying the mixture of polypeptides for use in the pharmaceutical product if the mixture of polypeptides has a predetermined average molecular weight.