one thing about SPE

[jiang295]

you have a very dirty aqueous sample including protein. when you use pure ACN to elute your sample, what will happen to protein? will protein be eluted out with ACN or precipitate. if protein precipitates, then will them be eluted out with ACN or stay in pore of silic particle and plug SPE?

[danko]

if protein precipitates, then will them be eluted out with ACN or stay in pore of silic particle and plug SPE?

Stay!

Best Regards

[HW Mueller]

Who in the world would inject protein precipitate??

[jiang295]

sorry, i did not state question very clear.
I can rephrase my question, after I load my protein sample, does protein precipitate within SPE catridge with pure ACN eluent. and does precipitated protein be eluted out with ACN or stay within SPE？
THANKS！

Who in the world would inject protein precipitate??

[HW Mueller]

Why would a protein, that has been precipitated out, move? Maybe there is an extremely mall portion in equilibrium with dissolution, so in a 100 years of elution your precipitate migth be gone. (There is also the possibility that the precipitate is fine enough that it is flushed out as such, that would obviate SPE).
jiang295, from your questions I surmise that you may gain more by learning the trade the conventional way, a forum is not a replacement of schools and books.

[jiang295]

sure, i am learning from both ways.
sometime, I just have a lot of confusion which is hard to be resolved from book.
for example, I do not know magnitude's difference between size of precipitated protein and interstitial radius space between pore. from your answer, I learn that
precipitated analytes should be much bigger than interstial space, so they wont elute out pre se.
this kind of answer is hard to be found out from book. do not you think so?

Why would a protein, that has been precipitated out, move? Maybe there is an extremely mall portion in equilibrium with dissolution, so in a 100 years of elution your precipitate migth be gone. (There is also the possibility that the precipitate is fine enough that it is flushed out as such, that would obviate SPE).
jiang295, from your questions I surmise that you may gain more by learning the trade the conventional way, a forum is not a replacement of schools and books.

[HW Mueller]

Well, books are bulky and heavy even though authors have the tendency to leave out the obvious, among other things, so that one can still carry the book. In this case a book may mention that you can use a 0.45 µm filter to remove protein precipitate from the solution, no need to tell people what the size of protein precipitate particles are. So the material you can not find readily in books are learned from lab courses, etc., and "reading between the lines", that is, by plain logic.