You can store them in 20% ethanol or PBS and sodium azide so that you can reuse them after washing. It is better to use new columns - Your efforts and other reagents are more expensive than those columns.

I would not reuse them.

The membrane is hydrophilic, to minimize protein binding, but you will have binding, nonetheless. On top of the filter membrane, you will have the formation of a protein membrane.

This protein will start to denature. Denatured protein will kind of turn inside out and the hydrophobic core will be exposed. The characteristics of the filter unit will change and your results will not be comparable or even reproducible.

Dear Ahmed.

you can wash them with milliq water to remove all the Salt and store at 4°C in 20% of ethanol also for long time. When i was student and we had strong buffer restriction i re-used it several time and it works. however while is simple remove the Salt and other buffer component , it not so simple wash well the inside membrane from the protein and to avoid cross contamination.

i reccomend to you to re-use it only for different preparation of the same protein but change it once you change your protein.

for desalting i suggest to you ti evaluate the pd-10 desalting coloums that are fast and do not stress your protein sample.

you can find some more informations about it at page 3 on my blog: ProteoCool

https://proteocool.blogspot.com/

ProteoCool n°8 (Buffer Exchange Methods overview) and

ProteoCool n°11(Rapid buffer Exchange by PD-10)

ciao

Manuele

Dear Ahmed,

Yes, I often recycle them. However, for reasons explained by others having to do with possible protein binding to surfaces, I only use them for the same protein. After recovering concentrated samples, I wash the membrane thoroughly several times with the same buffer, and I keep them hydrated and well closed at 4°C.

When running new rounds of concentration using an old device, I always keep an eye to the filtrate in first steps, in case the membrane resulted damaged upon storage and my proteins pass through. It happened just once.

Best regards

I'm agree with Fernando that is it better to check membrane resulted damaged from the TIPS when you remove the sample or upon storage and my proteins pass through.

Yo can easly check it this happen by check the out and the inn with Bradford reagent 1X.

Generally i distribute 100ul of the biorad reagent 1X (reagent 5X http://www.bio-rad.com/it-it/sku/5000006-bio-rad-protein-assay-dye-reagent-concentrate-450-ml?ID=5000006 diuted 5 times in water) for each eppendorf 1.5ml or well of 96well-plates and 10ul of the out and of the in were mixed with it.

If the concentrator is broken and the protein pass trough to the membrane you will se similar blue coloration in the inside and outside fractions which do not happen if the membrane is good and the protein is concentrating.

ciao

Manuele

After the first concentration is done, clean the column by passing water. Store the column in 20% Ethanol. You can use the concentrator for the same protein again.