Abstract: The present paper decribes a fiber optical sensor with a high sensitivity to determine sulfur dioxide. In order to improve the sensitivity, a non-steady state approach was adopted and the sensor response was recorded after the reaction being proceeded for 1 or 2 min. Effects of NaHSO₃ concentration and thickness of sensing layer of liquid on the sensor response were investigated. Agood linearity in a wide concentration range of sulfur dioxide, 3.1×10^-7 ～7.8×10^-5 mol/L, was displayed. The detection limit was 1.6×10^-7 mol/L. Using the sensor to determine the amounts of SO₂ in the wine, the results were in good agreement with the results obtained by the standard method.

Key words: Fiber optical sensor, Sulfur dioxide, Kinetic measurement