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Quiz 1. Describe the curve for dialysis over time Describe what controls the rate of mass transfer in dialysis. Show by calculation the number of buffer changes to reach 1 millimolar salt concentration from an initial concentration of 1 molar if you have 100 ml of solution in a dialysis bag and a
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1. Dialysis and Filtration Dealing with the little things
2. Quiz 1 Describe the curve for dialysis over time
Describe what controls the rate of mass transfer in dialysis.
Show by calculation the number of buffer changes to reach 1 millimolar salt concentration from an initial concentration of 1 molar if you have 100 ml of solution in a dialysis bag and a 500 ml beaker. State any assumptions you make about the system. Assume there is an infinite supply of salt free buffer.
3. Parts 1. Theory
2. Dialysis tubing/cassettes
3. Filters and membranes
4. Ultrafiltration
5. Microconcentrator
4. Dialysis Permeable membrane that selects molecules based on size.
Lower end of molecular weight cut off is about 8-10kd
Standard tubing is 12-14 kd
Rate of flux is
jd = K p,dialysis DC
J= flux
K = permeability constant of dialysis,
DC=Concentration difference
6. Ultra-filtration utilizes permeable membrane filters to separate the components of solutions and suspensions based on their molecular size
used for the concentration, desalting, or fractionation of mixtures of biomolecules.
Membranes come in a variaty of pore sizes from as small as 1000 to 1,000,000 da
> Millipore and Pall are the biguns
8. Ultra-filtration Concentration
Choose a membrane that retains the molecule of interest
desalting/buffer exchange
Choose a membrane that retains the molecule of interest and lets ligands and salts through.
fractionation of mixtures of biomolecules
One can either retain and concentrate
Pass through
9. Ultra-filtration
10. Ultra-filtration
11. Ultra-filtration Several different styles of units
Centrifugal systems
Uses centrifugal force to generate pressure gradient
Direct VS indirect
12. Millipore* Microcon*, Centricon* and Centriplus
13. Millipore* Centriprep*
14. Millipore* Ultrafree
15. Continuous filtration
16. Ultra-filtration kinetics
17. Buffer exchange rates