Abstract: In the present method, a new , simple and rapid spectopho-
tometric flow injection technique for the accuracy and determina-
lion of I^-in reservoir water has been developed. The method is
based on the decrease of absorbance intensity of rhodamine B
due to the complexation with[I₂Br]^-，I^-can be selectively ox-
idated to form I₂ by Ce(Ⅳ)in acidic medium and Iz reacts with
Br^-to form[I₂Br]^-，At this moment, some changes of the so-
lotion's color takes place. It is found useful for sensitivity in CT-
MAB media. The absorption peak of the complexation, which is
increased linearly By addition of I^-，occurs at 585 nm. Optimi-
zation of chemical and flow injection variables has been made.
Under the optimized conditions，the calibration curve obtained is
linear over the range 0. 0500~1. 00 mg/L, the linear equation
is H(mV) =76.6c(mg/L)-2. 933 3，r=0. 999 6，the de-
section limit is 0. 020 mg/L, and the precision(RSD=0. 85 %，
n=11 )is found quite satisfactory. This method has good sensi-
tivity and selectivity. Application of the method to the analysis
on I^-in reservoir water resulted a good agreement between the
expected and found values.