Updated project metadata. We tested here the ability of weak cation exchange (WCX) stationary phase to retain positively charged proteinaceous whilst negatively charged SDS molecules can be washed out from the capillary during on-line desalting. This novel chromatographic method named as online desalting of sodium dodecyl sulfate (online deSDS) satisfactorily allows for the first time the unforeseen straightforward LC-MS/MS analysis of SDS-containing samples without the requirement of any additional pre-processing step.