Patent ID: 7615359

Claim:
A process for determining the average molecular weight of a mixture of polypeptides, each of which consists essentially of alanine, glutamic acid, tyrosine and lysine, which comprises subjecting the mixture to chromatography on a chromatographic column so as to determine the average molecular weight of the mixture, wherein the chromatographic column is calibrated by using a plurality of molecular weight markers to establish a relationship between retention time on the chromatographic column and molecular weight, wherein each of the molecular weight markers is a polypeptide consisting essentially of alanine, glutamic acid, tyrosine and lysine and having a defined molecular weight, wherein in the mixture of polypeptides the molar fraction of alanine is 0.427, of glutamic acid is 0.141, of lysine is 0.337 and of tyrosine is 0.093.