A simple and rapid electrochemiluminescence (ECL) method is developed by using Tb(bpy)23+–K2S2O8 system for the determination of trace amounts of ciprofloxacin (CPFX). Conditions for ECL emission were optimized. Under optimized condition, the linear range of ECL intensity versus concentrations of CPFX is 6 × 10−8 to 1.0 × 10−6 mol dm−3 with a relative standard deviation (R.S.D.) of 3.8% (n = 11) and the detection limit is 1.4 × 10−9 mol dm−3 for CPFX. The ECL emission spectra (the peaks are at 490, 545, 585 and 620 nm) match the characteristic emission spectrum of Tb3+, indicating that the emission is from the excited state of Tb3+. The enhanced mechanism of Tb(bpy)23+–K2S2O8 ECL system was proposed. This method was successfully applied to determine CPFX in tablets.
