Work fluid and method for detecting chlorine ion in water steam of power plant and application thereof

The invention provides a work fluid and a method for detecting chlorine ion in water steam of power plant and an application thereof . The work fluid includes an eluent and a reaction reagent, wherein the eluent is a Na2CO3-NaHCO3 buffer liquid, both the Na2CO3 and the NaHCO3 being 0.001-0.05 mol/L in concentration. The reaction reagent comprises: 0.001-0.05 wt% of a color developing agent, 0.1-5.0 wt% of ferric perchlorate, less than 0.1 v% of perchloric acid or nitric acid, preferably the perchloric acid, 5.0-15 v% of methanol and the balanced being high-purity water. The invention also provides the method for detecting the chlorine ion in water steam of the power plant with the work fluid and the application thereof. The method achieves automatic and quick detection of chlorine ions in trace amount in the water steam of a power plant, detection threshold being 0.5 [mu]g/L.