Voltammetric Determination of Diffusion Coefficients in Polymer Membranes: Guidelines to Minimize Errors


Diffusion coefficients are important in the design, optimization, and selection of membranes used in many applications including chemical and biosensors. Since the diffusion-controlled transport of the analyte and interfering ions and molecules through polymer membranes may affect the rate of response, detection limit, selectivity, lifetime, etc. of chemical and biosensors, having a rapid and accurate method for the determination of diffusion coefficients of different compounds in a variety of membranes is uniquely important. In our contribution, we present a simple protocol for the rapid determination of the diffusion coefficients of electrochemically active analytes by linear sweep voltammetry. The expected errors in the estimated coefficients have been analyzed through modeling and the correlation between the magnitude of the unknown diffusion coefficients and the method's related maximum error is presented as a contour plot for different working electrode dimensions. It is also shown that our analysis protocol can be used to estimate the diffusion coefficient in complex membrane matrices and non-ideal experimental conditions with a maximum systematic error of 14 % even without any experimental parameter optimization.

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