Use of a Digital Computer for Evaluating Ultracentrifuge Data

Abstract

Fujita and MacCosham¹ have integrated Lamm's differential equation² for the ultracentrifuge, and have given analytical solutions which describe the integral and differential forms of the solute boundary for the sedimentation of a two-component system. They suggest that their equations may be of practical value in sedimentation analysis; but until recently the use of these equations for the routine estimation of molecular weights has not been possible because of the time required to perform the necessary calculations. This limitation no longer applies if the arithmetic is carried out by digital computer, and this communication shows how the equations can be used to evaluate apparent molecular weights from centrifuge data that would normally be treated by the method of Archibald³. The limitations inherent in the method arise chiefly from the assumption of Fujita and MacCosham that the sedimentation and diffusion coefficients, S and D, of the solute are independent of concentration. This may restrict the usefulness of the method to a particular class of solutes.