Abstract: The Cl- liberated by the electrolytic decomposition of chloroacetone (I) and the decomposition of I and 1-chloro-4-nitrobenzene by UV radiation was determined by using the detector of Ilcheva and Cammann (Ibid., 1985, 322, 323). The detection limit was in the nmol range. In the analysis of 50 µL of a 1 mM solution of Cl compound the coefficient of variation was ~5%. The detector, which can also be used to determine Br-, I- and S2- by using an appropriate ion-selective electrode, may be useful in LC.