Approaches to in-line removal of dissolved oxygen in flow systems for process analysis

Two methods for the removal of oxygen in analytical flow systems are described. Efficient deoxygenation can be realized by introducing N2 into the stream to form a two-phase flow combined with a membrane gas-liquid separator. A similar effect can be obtained by passing the flow through a length of Poreflon membrane tubing placed in a water bath at 100 °C. These methods are simple and rapid and remove more than 98% of the oxygen originally present. In order to evaluate the efficiencies of oxygen removal by these methods, we developed a reversed (reagent injection)-FIA system utilizing pyrogallol for spectrophotometric oxygen determination.