BSA and DDM diffusion with SC256 and 10mM salts
In my last post I showed that using buffered solutions instead of Di-water we could obtained similar results with SC256 as we had with SC269. I used 20mM HEPES at pH7.5 with no salts and showed DDM diffusion through both “treated” and “untreated” SC256 samples. Additionally I showed that “treated” SC256 samples appeared to slow diffusion of BSA across the membrane. Yesterday I decided to introduce salts into solution by setting up another diffusion experiment with “treated” and “untreated” SC256 samples.The initial retentate for this experiment consisted of 1.0% DDM and 2.5mg/mL BSA in a 20mM HEPES solution at pH7.5 with 10mM NaCl. I allowed the setup to sit overnight and ran the analysis this morning.
DDM Analysis:
As we have seen with previous experiments it appears that relatively equal amounts of DDM are diffusing across both the “treated” and “untreated” SC256 samples. The final DDM filtrate concentration for the “untreated” SC256 sample was ~0.050% and the final DDM filtrate concentration for the “treated” SC256 sample was ~0.054%.
BSA Analysis:
The diffusion of BSA across both the “treated” and “untreated” SC256 samples is relatively low but in this experiment the filtrate concentration for the “treated” sample was larger then that of the “untreated” sample. I used vacuum grease for both samples so I am going to setup another diffusion experiment today to double check this result. The final BSA filtrate concentration for the “untreated” sample was ~0.06mg/mL and the final BSA filtrate concentration for the “treated” sample was ~0.10mg/mL.
