A new fluorescence detector with good sensitivity for both fluorescent and non-fluorescent species is described. In this device, a fluorescent probe (aniline) is used in the liquid chromatographic mobile phase; fluorescent species give positive peaks and non-fluorescent or weakly fluorescent species give negative peaks. Detection limits in the part per billion range result for fluorescent species and in the part per million range for non-fluorescent species. Multiple peaks for ethanol and methanol are observed.