Abstract: Flow injection analysis methods are presented for determination of S2- in solution, residual Cl in solution, and aromatic sulfonylhaloamines (e.g., chloramine-T and chloramine-B) and Fe(III) based on previously reported spectrophotometric methods. Optimum conditions for all the determinations are described. The detection limits were 0.14 to 1.4 ppm and max. sampling rates were >200 samples h-1. Beer's law ranges and tolerance limits for diverse ions are reported. At pH 4.0, Fe (23.4 ppm) was determined in the presence of 120 ppm of Fe by using the reaction with sulfosalicylic acid. Chlorine in seawater samples and iron in steel were determined by the described methods.