The feasibility of combining the techniques of online concentration and CE/low-temperature fluorescence spectroscopy in the detection and identification of EE-4,4'bis(2-sulfostyryl)biphenyl (DSBP) in synthetic detergents at 77 K is demonstrated. The technique involves the use of sweeping-MEKC, and was used for the initial online concentration and separation, after which a cryogenic molecular fluorescence experiment was performed at 77 K. The proposed method not only permits the separation and detection of E,E-DSBP in a synthetic detergent sample, but also ensures that the online spectrum is readily distinguishable and can be unambiguously assigned at 77 K. The photoconversion and isomer separation of DSBP are also described.