One embodiment of the invention provides a method of preparing an eluted sample containing salts or buffers from a liquid chromatography device for analysis by a mass spectrometry device. The method includes: continuously providing a non-polar solvent to the mass spectrometry device; receiving the eluted sample from the liquid chromatography device; flowing the eluted sample over a solid phase extraction column; flowing the non-polar solvent over the solid phase extraction column; and presenting non-polar solvent and the eluted sample to the mass spectrometry device.