The response surface of an amperometric flow cell detector based on a rotating disk electrode for h.p.l.c.and continuous flow analysis

The amperometric detector flow cell based on a rotating disk electrode can be used in conjunction with continuous flow analysis as well as with h.p.l.c. The response surface of the detector as a function of flow rate, electrode rotation speed and concentration of electroactive species (hexacyanoferrate(II)) is measured in combination with continuous flow analysis. When the electrode is stationary, the detector behaves as a wall-jet detector. Rotating the electrode results in a completely different hydrodynamic flow pattern in the flow cell. The response becomes independent of the flow rate and is linearly related to the electrode rotation speed. The influence of nozzle height in the flow cell on the detector response in combination with h.p.l.c. is described. With certain combinations of nozzle height and rotation speeds, a favourable flow pattern appears to be created in the cell and the sensitivity is increased considerably.