Whatman filter Use ???

[bigguns175]

Quick question.

I know when you have your gear in your syringe you attach a whatman and shoot it through it and it filters the gear.

I was wondering are whatman filters one way filtration systems or are they bi-directional?   Could i use one whatman to suck my gear up through it for a first filtering.  Then change the whatman with a new one and then shoot the gear through the new one into a vial for a second filtering?

[bigguns175]

Well this is weird but I guess I'm going to answer my own question, but if anyone has further info that would be great.  From what I have read it seems like it depends on the brand of your filter if it is bi-direction the ones by microstar and cole-parmer are bi-directional.  Not sure about Schleicher & Schuell filters though, if you know please post the info.

[Vet]

You answered your own question.  Most Whatmans are unidirectional.  The do make them as a bidirectional filter (I think that has a different name too, but i'm having a brain fart), but if you think about that, it doesn't make much sense.  You push a liquid through the filter and filter out whatever it is you are filtering and then you suck something back up through the filter so you recontaminate what you sucked up with what you just filtered?    The only place I know those are used are in certian assays where the filtrate is a reagent (say DNA or proteins) for the second part of the experiment. 

That is not what you are using the filters for.   Get the unidirectional ones.