A HIGH-SPEED COMPUTERIZED POLAROGRAPHIC SYSTEM FOR CATHODIC STRIPPING VOLTAMMETRY IN SEAWATER

A low-cost computer-controlled high-speed polarographic system has been devised to determine heavy metals in seawater using adsorptive stripping voltammetry. The system consists of a potentiostat that has been developed in our Department, a 303A PAR polarographic cell, a personal computer with an I/O digital board PIO-96, and a hp7440 plotter. The potentiostat operates between -2.5 and +2.5 V, with a multirange selection current between +/-100 nA and +/-1000 mu A. There are various outlet channels with different time constants and noise levels. The quickest channel can detect processes in a 10 mu s range with a noise level of +/-4 nA (seawater matrix), while for a range of 30 ms, the noise is +/-100 pA. The software controls different signal patterns, techniques, and a complete set of operations and has been developed in the C language to accelerate the data acquisition. The system has been successfully applied to high-speed cathodic stripping voltammetry (HSCSV) on seawater samples, showing promising results in that there is an increase in the sensitivity over standard methods in the presence of oxygen and in stirred solutions. The analysis time can be reduced significantly at a high speed, and also, determinations aboard a ship are improved.