title: Colour reaction of free chlorine with p-amino-N,N-diethylaniline in the presence of alcohol and its analytical application.
abstract: A simple, precise, rapid-colour-forming and stable spectrometric method has been developed for determining free chlorine in water. p-Amino-N,N-diethylaniline reacts with free chlorine almost instantaneously in the presence of alcohol to form a red oxidized product with absorption maximum at 513 nm. Beer's law is obeyed in the free chlorine concentration range of 0-2 microg ml(-1). The molar absorptivity is 1.79 x 10(4) l mol(-1) cm(-1), limit of detection 0.0036 microg ml(-1), relative standard deviation 1.51%, and amount of free chlorine 7 microg. The colour reaction rate and absorbance are independent of temperature in the range 3-45 degrees C and the stable absorptivity lasts for at least 1 h. The method is satisfactory for the determination of free chlorine in aqueous solution.
authors.affiliation: Department of Chemical Engineering, Changsha Industrial College, Changsha, People's Republic of China.
authors.forename: M
authors.initials: M
authors.lastname: Zhang
authors.forename: Q
authors.initials: Q
authors.lastname: Zhang
authors.forename: Z
authors.initials: Z
authors.lastname: Fang