Methods and systems for determining relative response factors for liquid chromatography using both molar concentration-based detection and mass concentration-based detection are described herein. A method includes determining a relative response factor for a compound based on the ratio of a molar-based peak area for the compound to the logarithm of the mass-based peak area for the compound and based on the ratio of a molar-based peak area for a reference compound divided by the logarithm of the mass-based peak area for the reference compound.