Comparison between the performance of an electrochemical detector flow cell in a potentiometric and an amperometric measuring system using glucose as a test compound
A wall jet type of electrochemical detector flow cell was constructed and tested in an amperometric and in a potentiometric detection system. In the amperometric detection system the test compound, glucose, was electrochemically oxidised at the working electrode. In combination with a simple flow injection analysis system the lower limit of detection was 20 p.p.m. of glucose whereas the upper limit of the linear dynamic response range was about 2000 p.p.m. of glucose.
Using the potentiometric detection system, the change in redox potential of an Fe(CN)63–-Fe(CN)64– solution, owing to the chemical oxidation of glucose by Fe(CN)63–, was measured. The response of the detection system at solutions with different [Fe(CN)63–] to [Fe(CN)64–] ratios was almost Nernstian. In a nitrogen segmented continuous flow analysis system, using Fe(CN)63– as the oxidising agent, a dynamic response range of 2–900 p.p.m. of glucose was measured.
For the amperometric and potentiometric detection system different response times and volumes were measured as a function of the flow-rate and the nozzle height in the flow cell.