Comparison of the Ultracentrifuge Method for Molecular Weight Determination with the Classical Methods*

Abstract

UP to the present there has been scant possibility for a direct comparison between the ordinary methods for the determination of molecular weights of substances in solution and the recently developed ultracentrifuge method. In fact, Adair's refined osmotic pressure measurements on haemoglobin,1 giving a value (66,000) that compares favourably with the ultracentrifuge value of 68,000,2 provided the only independent data. It was therefore thought desirable to attempt a comparison on a substance of sufficiently low molecular weight to give fairly trustworthy results with the ordinary methods of boiling-point elevation or freezing-point lowering.