A FERROUS ION-OPTICAL SENSOR-BASED ON FLUORESCENCE QUENCHING

A ferrous ion optical sensor is prepared by adsorbing Calcein Blue (CB) on a hydrophobic support incorporated in a flow cell. The sensor based on the fluorescence quenching of CB at pH = 2.2 is sensitive to ferrous ions over a wide range of analytical interest (1-500 mu M), with a linear and efficient quenching region at the lowest iron concentrations, from 10(-6) to 10(-5) hi. The time to reach steady-state fluorescence is very long and is governed by both slow complexation reaction and mass transfer. The immobilised reagent has been regenerated by addition of acidic chelating agents.