edited by GALEN W. EWING Seton Hall Unwersnty South Orange, hew .erse) 07079
XCII. A Low-Cost Voltammetric Signal Generator for the Electroanalytical Chemistry Laboratory Chia-yu Ll' and Jesse E. Gillikin, Jr.2 East Carolina University Greenville, North Carolina 27834
INTRODUCTION With the advent of modern electronic technology, many sophisticated polarographic measurements can be made with relative ease. Today's instrumentation for palarography generally includes a potentiostat, a signal generator, a measuring and recording system, and an electrode assembly. The difference between various polarographic techniques depends mostly on the types of signal applied to the potentiostat. For example, in the ease of direct w e n t (dc) oolaroma~hv. .. ,. a ramu sienal .. is used:.in cvclie , voltammctrv tor ctatimary elecrnrde polarugraphv,, the signal iouree is a triangular wave; in alternating current (ac) polarography, a small amplitude sinusoidal wave superimposed on a ramp signal is used as the signal source; and in pulse polarography, synchronized short voltage pulses with linearly increasing amplitude are applied. Among all these techniques, cyclic voltammetry is probably most popular t o use for studying the kinetics and mechanism of electrochemical reactions. This is largely due to the simplicity of its signal source and detection system. The theory of cyclic voltammetry was worked out hy Nicholson and Shain in 1964 (1-3) andsinee then, countless research articles on the application of this technique have appeared in the literature. This paper describes the construction of a versatile signal generator suitable for use in cyclic voltammetric experiments. The signal generator can be conveniently adapted t o a conventional dc oolaro~raoh . . . hv, simolv replacing its ramp wurre with this genrrator. A far1 rerpmar XY-recorder or an oscilluscope should he used as the recording device.
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'To whom communieation~mneemingthis paper should be addressed. 2Present address, Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27607.
During the past decade, numerous signal generator designs have been reported; Schroeder made a rather comprehensive review of this subject in 1972 ( 4 ) . More recent examples of the signal generator have adooted solid-state and dieital cireuitrv 1.5-1t11.A n external rampsourre wau used hy Li. Ftrrier, and Schmwlrr 11, sywhnmiac the oscilloscope sweep and the recorded eurrent-voltage curve (5). Direct on-line application with eomputer-programmable devices was reported by Perone, e t al. ( 6 ) ,later by Farwell (7),and more recently by Kolvoda, e t al. (8). seemed . . These desiens. .. . however.,~~~ eithrr too rophlatwatrd or over-speciali,rd for a general purpos* underprndunre glr even graduate level teaching laboratory. Of the several commercially available U S . models on the market, it appears that the cost factor is still a hindrance to their universal acquisition hv manv teaehine laboratories. The need was thrrrforr l'dt ior the deiim
