I have tried to separate aggregates from xylan and arabinoxylan solutions by passing them through common 0.22 um syringe filters. However, the polysaccharide content after filtration was drastically reduced, probably due to interactions with the membrane. Also, I have observed the same behavior when I try to filter carbohydrate active enzymes. Is there a specific filter or manner to quickly filtrate these materials?
can u see polarized the membrane? maybe if you uses a .45 um will be better
Waouh, this brings back old memories! You're not the first to notice this, look up for example Carbohydrate Polymers 31 (1996) 41, also with arabinoxylans. Carbohydrate polymers are notoriously difficult to really dissolve, they readily form aggregates. How did you dissolve them? You might try patience (overnight), ultrasonication (filtrate quickly, and do not be surprised at reprecipitation), heating (same remark as ultrasound), addition of a chaotropic agent, alkaline medium if the column will bear it...
I learned when working with seaweed polysaccharides that membrane filters clog very quickly with viscous high-MW polymers. Have you tried glass fiber filters, either alone or as prefilters? There are several porosity types available. Whatman GF/F is one of the finest pore sizes, but is still substantially larger than 0.22 µm (it is closer to 0.7 µm). There are also pressure cells that use pressurized nitrogen or air to force the suspensions through a filter. I used to stack glass fiber filters on top of membrane filters, and wrap heating tape around the pressure cell to keep agar from gelling as it was filtered.
You might try to precipitate the polysaccharides e.g. with ethanol rather then filter. (Obviously depending on what you wanna do next.)
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