Dextran vs BSA:

Most of our users add 0.15% serum albumin as an osmotic agent as opposed to dextran, for several reasons:

-BSA is a better  blocking and carrier agent than dextran for preventing binding of peptides and proteins to plastic surfaces (probe, tubing, swivel, sample storage tubes).

-BSA acts as a sacrificial substrate for proteases in the perfusate.

-Dextran can cause a strong immune response if it leaks out of the probe. With 100 kDa MWCO probes, if you are going to use dextran, I would suggest using Dextran 500:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4004663/ 

However, the presence of BSA makes LC-MS analysis much more difficult