Abstract: Reagent (2,4-dinitrophenylhydrazine in H2SO4 and HCl or acetic acid; preparation details given) was injected into a carrier stream (0.36 ml/min) of 0.2 M KCl adjusted to pH 1 with 0.2 M HCl and the carrier stream merged with the sample stream (0.93 ml/min). The merged stream passed through a reaction coil (105 cm x 0.5 mm i.d.) and the absorbance was measured at 360 nm. Beer's law was obeyed for 0.1-10 mg/l chlorine with a detection limit of 0.05 mg/l. The effects of foreign ions are tabulated. The method was applied to the analysis of natural and drinking water with RSD of 2.3% for chlorine and chloramine.

Abstract: A continuous-flow system is described and illustrated, for simultaneous determination of chloramide (I), chlorimide (II) and free Cl in water, which incorporates three double-tube separation units, each consisting of a PTFE outer tube and an inner tube of micro-porous PTFE. The three tubes were used for determination of I, I plus II, and I, II and Cl, respectively, by reaction with I- and absorbance measurement at 288 nm. Optimum pH and reagent concentration. for each reaction are given. Calibration graphs covered the ranges from 0.1, 0.02 and 0.02 mg L-1 of Cl for I, II and free Cl, respectively, to 71 mg L-1 for all Cl species. Within- and between-run coefficient of variation were 3.3% (n = 5) and 10% (n = 8), respectively. The method was applied in monitoring of I and II in water purification plants.