Separate salts from peptides by RPHPLC?

[qzhang]

I am just wondering is there any good modifiers for the solvent to separate salts from peptides? My analyte is in PH 2 buffer. We have c18 columns.
95% H2O 4.5%acn 0.5% formic acid as A
95% acn 4.5%h2o 0. 5% formic acid as B




Will DMSO be useful as a modifier for mobile phase

[tom jupille]

Most inorganic salts are unretained in reversed-phase HPLC, so any system that retains your peptides will do the job. However, bear in mind that at pH 2, most peptides will be positively charged and must have negative counterions present (presumably trifluoroacetate).

[XL]

Do you want to measure the quantity of the salts, or eliminate the interference of salts from peptide analysis? If salts are the analytes of interest, what are these salts?