[ri′vərst ¦fāz pär′tish·ən ‚krō·mə′täg·rə·fē] (analytical chemistry) Paper chromatography in which the low-polarity phase (such as paraffin, paraffin jelly, or grease) is put onto the support (paper) and the high-polarity phase (such as water, acids, or organic solvents) is allowed to flow over it.