MTech POL-20 – universal polarograph for electrochemical analytical methods

Abstract

The simple version of multyfunctional universal polarograph MTech POL-20 based on microcontroller C8051F350 has been designed. The polarograph has functionalities of potentiostat and galvanostat. The C8051F350 chip is fully integrated, low power, mixed-signal system-on-a-chip microconroller unit. It includes high-speed 8051-compatible core, precision programmable 24.5 MHz internal oscillator, 8 kbytes of on-chip flash memory, 24-bit analog to digital converter with analog multiplexer, two 8-bit current output digital to analog converters and 2.5 V voltage reference. The polarograph controls the potential between the working electrode and the reference electrode in range ±2.5 V. The device has four ranges of measured current with programmed selecting: ±15, ±100, ±500 and ±2500 uA. The device can measure voltammograms under high sweep rate from 0.01 and up to 100 mV/s. The polarograph is equipped with RS232-USB converter based on PL2303 chip for power supply and communication with the computer through USB port. Computer program on Visual Basic 5.0 language for operating with potentiostat has been developed. This software allow to measure and visualize voltamperograms, chronopotentiograms and chronoamperograms. For reduction of influence of electromagnetic noise and improvement signal/noise ratio the program makes digital processing of measured polarograms by Savitzky-Golay filter. Potentiostat-galvanostat MTech POL-20 has been successfully tested on model systems using resistive electrochemical equivalents. Also, the polarograph was successfully tested on determination of Pb(II) by anodic stripping voltammetry method. The device is suitable for the main electrochemical measuring techniques and well-known analysis methods: potentiometry and potentiometric titration, coulometry and coulometric titration, voltammetry with different types of potential sweep – linear, normal pulse, differential pulse and square-wave. Keywords : polarograph, potentiostat, galvanostat, microcontroller C8051F350, voltammetry, potentiometry.