A 0.5 M methanesulfonic acid (MSA) solution is commonly used as an eluent or mobile-phase concentrate in ion chromatography particularly for the separation and analysis of cations.

Its purpose is to provide a controlled acidic eluent concentration that facilitates the separation of ionic compounds and helps maintain consistent analytical performance during chromatographic analysis.

Methanesulfonic acid 0.5 M solution is an aqueous solution containing 0.5 moles of methanesulfonic acid per liter of solution. It is typically supplied as an eluent concentrate for dilution or direct use according to the analytical method and instrument requirements.