I've done some replicas on same sample (more than two but to simplify the question I've just plot two of the experiment) and obtained the result attached. It's a reasonable result for the samples I have and also the variance between the replicas is ok. I cannot obtain "same" curve and I already knew that. They are different from another sample. My question is .. if you look at the plot that generically are plot in papers about electrochemistry you cannot find an idea on the variance on the samples so how to average my samples to obtain one curve ?