An other way would be to load the IEX eluate on a C18 trap column from an LC/MS system, wash for an extended time and elute from the trap column onto the analytical column of the lc/ms system. It wolud be an option, if you have limited access to the sample.

This depends on the target analyte. Ziptips can be applied for proteins and peptides as well as for other hydrophobic compounds.

Thank you for your answer:

I did cation exchange to venom sample. Also I did ziptip before for proteins and peptides but after another type of separation. The problem with me now the high concentration of salt, I need to know i can do ziptip to fractions with high salt or there is another method.

Yes, it's OK to load IEX eluates into ziptips. First you have to equilibrate the sample using formic acid or TFA (I just mix with an equal volume of 5% formic acid). It might also be healthy to increase the number of washing cycles and do them with a larger volume (say, pipetting onto 200 uL).

In case your levels of salts are too higher, you can also use Dialysis Tubing. There are too many in the market with high recovery results!

Good luck!

An other way would be to load the IEX eluate on a C18 trap column from an LC/MS system, wash for an extended time and elute from the trap column onto the analytical column of the lc/ms system. It wolud be an option, if you have limited access to the sample.

Thanks all for answer

How about Buffer choice method, which can be used to determine the success of ion exchange purification. The general nature of the buffer, concentration of the buffer, and the pKa of the buffer should all be considered. How all these properties relate to ion exchange chromatography is best understood after gaining a solid understanding of the concept of ionic strength of the buffer solution.

The pKa of a buffer is commonly perceived as the pH of the said buffer when the concentrations of the two buffering species are equal, and where the maximum buffering capacity is achieved. However, it is often forgotten, that when defined as above, pKa depends on buffer concentration and temperature. To avoid this problem the concept of “thermodynamic” pKa0 was introduced. pKa0 is pKa of the buffer at infinite dilution (buffer concentration=0) and 25oC. Thus, pKa0 is a true constant specific for a given buffer.

In practice, this means that if one prepares the buffer concentrate by mixing of equal amounts of two buffering species, the buffer pH will indeed be equal to the buffer pKa (but not pKa0). Now, if one dilutes the said buffer concentrate, the solution will change its pH because pKa is changing with buffer concentration. If one further dilutes this buffer (infinite dilution at 25oC) buffer pH becomes equal pKa0.

https://www.researchgate.net/post/Does_anyone_have_an_idea_how_to_resolve_the_problem_of_cation_exchange_in_chromatography_salts?_sg=V8K16WQ2fnhoodDU%2By63op4KZaSvI1lCW7k9z%2BX960z9rGrk0uYfiOzd1Lj6vhP1

What was the method used for cation exchange? Using cation exchange gels / resins can be problematic if not used correctly.

I used TSK gel column in separation my sample

There are a number of TSK gel columns offered for cation/anion exchange using HPLC. What is the charge of the item of interest (why add the salt) and the conditions for the HPLC run?

I've already used a Centricon with 3K membrane and 500 uL capacity. After concentration, I washed the sample with water. But the best method is applying your sample in a reverse phase column because you can remove salt and check the purity.

You may try a product (Zeba Spin Desalting Column) of Thermo Scientific.

http://thermofisherscientific.wistia.com/medias/v4opiny2e2?utm_campaign=BID_PRO_PR_EM_ZebaVideo1_EU&utm_medium=email&utm_source=internal&wt.mc_id=BID_PRO_PR_EM_ZebaVideo1_EU

Which kind of mass spec system you have? Usually, we also could setup an online desalting system using C18 trap column, which could reduce sample loss and save time.

I guess we are talking about peptides, if so the only way that I think is to desalt the samples in a C18 cartridge, depending on the amount of material you can use ZipTip (for up to 5ug of) if more some kind of tip with higher capacity.

but if it's protein , dialysis is the best, there are few kits form different vendor available.

I hope that this help you