Rethinking Data Collection and Signal Processing. 2. Preserving the Temporal Fidelity of Electrochemical Measurements

• Published in: Analytical chemistry (Washington) Vol. 85; no. 16; pp. 7654 - 7658
• Main Authors: Atcherley, Christopher W, Vreeland, Richard F, Monroe, Eric B, Sanchez-Gomez, Esther, Heien, Michael L
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 20.08.2013
• Subjects: Analytical chemistry; Animals; Background noise; Constants; Data Collection; Electrochemical Techniques - standards; Exocytosis; Filtering; Fourier Analysis; Kinetics; Mathematical analysis; Molecular chemistry; Noise; PC12 Cells; Phase (cyclic); Preserving; Rats; Signal Processing, Computer-Assisted; Signal to noise ratio; Signal transduction; Symbols; Waveform analysis
• ISSN: 0003-2700; 1520-6882
• DOI: 10.1021/ac402037k

Direct electrochemical measurements of biological events are often challenging because of the low signal relative to the magnitude of the background and noise. When choosing a data processing approach, the frequency and phase content of the data must be considered. Here, we employ a zero-phase (infinite impulse response (IIR)) filter to remove the noise from the analytical signal, while preserving the phase content. In fast-scan cyclic voltammetry, the frequency content of the signal is a function of the scan rate of the applied waveform. Fourier analysis was used to develop a relationship between scan rate and the filter cutoff frequency to maximize the reduction in noise, while not altering the true nature of the analytical signal. The zero-phase filter has the same effect as traditional filters with regards to increasing the signal-to-noise ratio. Because the zero-phase filter does not introduce a change to ΔE peak, the heterogeneous electron rate transfer constant (0.10 cm/s) for ferrocene is calculated accurately. The zero-phase filter also improves electrochemical analysis of signaling molecules that have their oxidation potential close to the switching potential. Lastly, a quantitative approach to filtering amperometric traces of exocytosis based on the rise time was developed.