The peak current of my modified electrode is approx. 40uA at 0.7V and the current increases when analyte is added. However, when I run it in chronoamperometry, the current is in nA range. When the analyte is added, the current increase to approx. 5uA (which is far more lower if compared to 50uA in CV).
In CV, the potential is swept whereas in amperometry potential is kept at a constant value and the current is monitored as a function of time. in other words, amperometry is a potentiostatic method in which the current is merely derived from faradaic reaction but Cv is a potentiodynamic method in which the current arises from both faradaic and nonfaradic processes.
In CV, the potential is swept whereas in amperometry potential is kept at a constant value and the current is monitored as a function of time. in other words, amperometry is a potentiostatic method in which the current is merely derived from faradaic reaction but Cv is a potentiodynamic method in which the current arises from both faradaic and nonfaradic processes.
Artur Braun
The current did decreasing rapidly when I swtich on the potential. But the initial current also not high as in CV, even in the blank electrolyte without the analyte.
As Hamid Reza Moazami said, this kind of comparison between the two techniques is wrong, they are basically different, please read prof.Allen J. Bard book.
Dear Pui Kee Lee,
could you remeasure the "same" chronoamperometry, using both conditions :
1) the maximum, available, rate[1] of the data recording, and
2) choose a non auto (manual) setting for the current range[2] ?
1. In the rare case of some high frequencies of (uA range, actual) current fluctuations, then you might "see" what you get : some nA range, as an illusive current.
2. Adopt a (near 10uA to) 50uA (manual) current range.
Hi Ioaanis Samaras
Thank you for your recommendation. However, the result is still the same with both conditions stated above.
ok. Also, adding an oscilloscope measurement (Vosc, for the i=Vosc/R) on a series resistance (R
Your electrode is of millimeters dimensions therefore the current on a potential step is going to decay to 0 rather than a limiting current as in a microelectrode. A better approach I believe is to compare theoretical value vs experimental value on cyclic voltammetry using the peak current equation. Hamed mentioned Dr. Bard electrochemical methods book which is a very good reference you can find what you are looking in that book chapter 5 and 6.
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