Differential interferometry in the analytical ultracentrifuge. II. General applications

✍ Scribed by Toshihiko Kondo; Masaya Kawakami

• Publisher: Elsevier Science
• Year: 1981
• Tongue: English
• Weight: 575 KB
• Volume: 117
• Category: Article
• ISSN: 0003-2697
• DOI: 10.1016/0003-2697(81)90794-6

✦ Synopsis

Various ways of applying differential interferometry to ultracentrifugal analyses are examined and several analytical techniques are established. In transport and moving boundary methods, the sedimentation coefficient is more precisely determined in the differential interference system than in the schlieren optical system because fringe measurement accuracy is much higher in the former system. Compared to interference and absorption optics, the differential interferometer provides a more exact s value in the transport method since an accurate calculation procedure can be adopted. Moreover, the following advantages of differential interferometry are noted. Determination of the initial solute concentration, which must be done in the usual interference method, is unnecessary in this sedimentation equilibrium method. Regardless of the partial loss of solute from the observed system due to rapid precipitation or adsorption to the cell wall during centrifugation, the molecular weight of the rest of the solute can be determined exactly. The diffusion coefficient can be determined accurately by fringe displacement analysis at the hinge point during the transient state. Together with the molecular weight and diffusion coefficient, the partial specific volume and sedimentation coefficient of a solute can be obtained from the result of a single low-speed centrifugation when the sample solutions in Hz0 and D,O are compared.