Temperature pulse modulated amperometry at compact electrochemical sensors

This communication reports about thermal modulation of amperometric signals by short heat pulses applied at directly heated gold electrodes. A gold layer together with a pseudo reference and counter electrode has been printed onto a low temperature cofired ceramic (LTCC) substrate. We chose hexacyanoferrate(II) and picric acid as model analytes in this preliminary study. Peak shaped amperometric signals were formed upon such thermal modulation. The peak current has been taken as the analytical information. Thermal modulation in amperometric measurements activates kinetically inhibited analytes such as picric acid. A linear calibration plot has been obtained ranging from 0.2 to 1 mmol/l. The background contribution was effectively suppressed, even at −0.7 V applied potential at the gold electrode. Convection did not significantly affect the analytical signal. This will be important for applications where convection is pulsating or is otherwise not under control and thus induces disturbances. Future applications include environmental monitoring, flow injection analysis, high performance liquid chromatography and capillary electrophoresis.