Potentiometric detection of aliphatic amines by flow injection analysis and ion-interaction chromatography with a metallic copper electrode

The detection of aliphatic amines in flow systems with a potentiometric method based on a metallic copper wire electrode is described. The electrode is shown to give sensitive response toward aliphatic amines in flow injection analysis. The parameters affecting the response characteristics of the electrode such as the pH of the carrier, the concentration of an ion-interaction reagent and the injection volume were investigated. The metallic copper electrode was applied to the detection of amines after separation by ion-interaction chromatography with a mobile phase containing a low concentration of octylammonium salicylate in unbuffered solution. Detection limits in the range of 0.5-1.0 nmol were obtained in the presence of 0.3 mM octylammonium salicylate at a pH of 6.0 and a flow-rate of 0.3 ml/min. A comparison of the potentiometric detection with conventional UV is given, showing comparable sensitivities. The potentiometric method offers a low cost, easily constructed detector with some possible applications.