Inhibition kinetic determination of trace amount of iodide by the spectrophotometric method with rhodamine B

Trace iodide was determined by inhibition kinetic method, which based on its inhibition effects on the reaction between rhodamine B (RhB) and KBrO(3) in H(2)SO(4) medium in 45+/-0.5 degrees C for 15 min. The signal difference (DeltaA, DeltaF) between inhibited reaction and non-inhibited reaction is linear with the concentration of iodide. The linear range were 2.0-6.0 and 1.0-6.0 ng mL(-1) and the detection limit were 0.06 and 0.07 ng mL(-1), respectively. The method has been applied satisfactorily to the determination of iodide in kelp.