{"in": [], "out": "chromatography solvent"}
{"in": ["chromatography solvent", "isobutanol"], "out": ""}
{"in": [], "out": "solvent vapors"}
{"in": ["", "solvent vapors"], "out": ""}
{"in": [], "out": "separated compounds"}
{"in": [], "out": ""}
{"in": [], "out": "urocanic acid"}
{"in": ["urocanic acid"], "out": ""}
{"in": [], "out": "the chromatogram"}
{"in": ["separated compounds"], "out": ""}
{"in": [], "out": ""}
{"in": [], "out": "imidazolyl derivatives"}
{"in": ["imidazolyl derivatives", "the Pauly diazo reagent"], "out": ""}
{"in": [], "out": "Rf values"}