A sensitive and stable IO4--H2O2 chemiluminescence (CL) system for flow injection determination of sodium dodecylbenzene sulfonate (SDBS) is described. Weak CL is emitted when H2O2 is oxidized by sodium periodate. In this system, various surfactants enhance CL intensity, especially SDBS. The effects of non-polar organic solvents on CL are also reported. The 3 sigma detection limit for SDBS is 3.2 x 10(-8) g ml(-1) in a system using a trace of cyclohexane and the relative standard deviation of this method is 1.6% at 1.0 x 10(-6) g ml(-1) for 11 determinations; SDBS in detergents is determined. (C) 2000 Elsevier Science B.V. All rights reserved.