Determination of residual chlorine in water supply by p-aminodimethyl aniline spectrophotometry

New method has been developed for determination of the residual chlorine in water supply by p-aminodimethyl aniline spectrophotometry. On some conditions, chlorine can oxidatep-aminodimethyl aniline,and make it become red oxidation state,and this method can quantifi-cationally determine chlorine,the experiment conditions as follows: the most absorption wavelengh is 520 nm,pH should be controlled between 2.5 and 4.0,the dosage of amortize liquid is 2 ml,the volume of showing color liquid is 3 ml.Beer's law is obeyed in the range of 0.1～2.0 mg/L of chlorine;the detection limit of chlorine is 0.02 mg/L.The method has been applied to determine of residual chlorine in some water samples with satisfactory results.