CHAPTER III 



CENTRIFUGATION 



E. G. PiCKELS, Specialized Instruments Corporation 



A. Fundamental Principles 68 



1 . Sedimentation in Uniform Field of Force 68 



2. Sedimentation in Centrifugal Field of Force 69 



3. Significance of Ultracentrifugal Method 71 



B. Ultracentrifuges of Optical Type 72 



1 . Ultracentrifuges of Vacuum Type 72 



2. Svedberg Ultracentrifuges 75 



3 . Optical Ultracentrifuges Exposed to Air Friction 77 



4. Optical Methods 77 



C. Mathematical Theory 83 



1 . Sedimentation Constant 83 



2 . Frictional Coefficient 84 



3 . Molecular Weight and Particle Size 85 



4 . Concentration Correction Factor 86 



D. Experimental Requirements 86 



1 . Preparation of Material 86 



2 . Measurement of Sedimentation Constant 87 



3. Determination of Partial Specific Volume 89 



4. Selection of Equipment and Methods 90 



E. Interpretation of Results 94 



1 . Significance of Frictional Ratio 94 



2 . Determination of Homogeneity 94 



3 . Accuracy and Limitations of the Method 96 



4 . Representative Applications 97 



F. Preparative Centrifugation and Quantitative Methods Based 



on Sampling 98 



1 . Preparative Centrifugation 98 



2. Sampling Techniques 100 



References 100 



67 



