Impurities present intracene have been concentrated by vapor zone refining, and identified by chromatography and absorption and mass spectroscopy. They include anthracene, pyrene, methylpyrene, chrysene, 5,12-dihydrotetracene, 1,2-benzodiphenylene oxide, 1,2-benezodiphenylene sulfide, brasan, 2,3-benzofluorene, 4,5-iminophenanthrene and 5,12-tetracenequinone. Eutectic mixures of tetracene with 2-naphthoic acid have been zone melted, and numerous impurities were concentrated. Zone melting the eutectic with added 2,3-benzofluorene gave effective segregation of the latter. Zone melting the anthracene/benzoic acid eutectic with added carbazole showed that k eff for the latter is 0.6, which is considerably lower than the values measured for the anthracene/carbazole system alone.