Journal of Neuroscience Methods, 25 (1988) 91-95 91 Elsevier NSM 00843 Research Papers Basic instrumentation for fast cyclic voltammetry J. Millar and T.G. Barnett Department of Physiology, The London Hospital Medical College, l~mdon ( U. K. ) (Received 14 December 1987) (Revised 8 March 1988) (Accepted 9 March 1988) Key words: Fast cyclic voltammetry; High-speed cyclic voltammetry: Carbon fibre electrode: In vivo voltammetry Fast cyclic voltammetry is a new voltammetric technique which has been especially useful for measurements of dopamine release in vivo. This paper describes methods for the construction of a basic fast cyclic voltammetric amplifier, and the associated apparatus necessary to carry out fast cyclic voltammetric experiments. Introduction Circuit details Fast or high-speed cyclic voltammetry (FCV) using carbon fibre working electrodes was first introduced as a way of measuring the extracellular concentration of catecholamines or indoleamines ejected from a micropipette by iontophoresis (Armstrong-James et al., 1981). It was initially developed as a 'time-share' system so that ex- tracellular single-unit activity could be monitored in between the electrochemical scans. More re- cently, the technique has been shown to be capa- ble of detecting endogenous dopamine released in the rat striatum after stimulation of the median forebrain bundle (Millar et al. 1985). This paper describes the circuits used in series of experiments using FCV to measure dopamine release (see re- view by Stamford, 1985). It does not include de- tails on data analysis as these may be found in waveform analysis packages on personal com- puters or 'smart' oscilloscopes. Correspondence: J. Millar, Department of Physiology. The London Hospital Medical College, Turner Street, London E1 2AD, London, U.K. Scan generator A triphasic ramp voltage was used as the active or 'scan' waveform in FCV (Fig. 1). The scan lasts some 15 20 ms, depending on the slope and am- plitude of the ramp. Scans are triggered usually at one per second. In most of the experiments on dopamine release, a scan giving a rate of change 500 mV 5msec Fig. 1. Triphasic voltage wa,~eform (scan waveform) in fast cyclic vohammetrv. 0165-0270/88/$03.50 a! 1988 Elsevier Science Publishers B.V. (Biomedical Division)