I have performed electrochemical sensors by carbon electrode modified with redox-active organic molecule as electrocatalyst. it shows the redox behavior at about -200mV in a buffer. With this working potential, the amperometry technique was used for the reduction of analyte to monitor the change in current with concentration. In my observation, the amperometry curve shows linear increments while the calibration curve shows non-linear behavior. The current was selected in the middle of the steady state of each addition of analyte. even low concentration range also shows the same. Even though the experiment was repeated, the same behavior was observed instead of a linear calibration curve. Though a non-linear curve, we can use but I would like to know the reasons behind this behavior. Thanks in advance
Balamurugan Thangavel notice in the amperometric curve that the current at "steady state" is not constant as the concentration increases, the higher the addition of analyte the higher the slope in the current response. So I think you have to try to reach the steady state conditions.
Javier Ernesto Vilaso Cadre Thank you very much for your response, even though the steady-state current is not constant at higher concentrations, it should saturate in the current response or multiple linear ranges should be obtained. But in this case, the low concentration range also shows non-linear behavior in the calibration plot. I am expecting the reason why non-linear behavior was obtained.
You can check these facts:
Inaccurate calibration
Aging of the sensor
Limited range of operation
Non-ideal behavior (diffusion limitations, surface coverage, catalytic effects)
Interference from other substances in the sample matrix
Tanzila Noushin Thank you for the response
I will consider the comments
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