Determination of the Concentration of Organic Compounds using an Electrochemical Test System

The research paper looks at the possibility of using an electrochemical test system to determine the concentration of organic compounds. The experiments were based on the fact that each class of organic substances required a specific test system. Since we were interested in sulfurcontaining organic compounds, the electrochemical test system was a solution containing cations of zinc, gallium, and copper. These metals can form complex compounds with sulfur-containing organic substances. When inserted into such a test system, organic substances of this class significantly alter its electrochemical behavior, which is reflected in stripping voltammograms. The experimental procedure and software made it possible to obtain the required number of parameters, which enabled a multisensory analysis on a single working (indicative) electrode. The stripping voltammograms recorded before and after addition of organic matter to the electrochemical test system were digitized; then one voltammogram (recorded when the test system contained no admixtures) was deducted from the other one (recorded when organic matter was added to the test system). The resulting difference curve was divided into segments; experiments showed that the number of segments should not exceed 20 or 30. These digitized curved sections were integrated in order to obtain a set of informative parameters, which can be viewed as a set of vectors, i.e., a multi-dimensional vector representation of each analyte. To visualize the results of the electroanalytical study, we represent the multidimensional image of organic substances of various concentrations as a number of vectors arranged in a circlel; the number of vectors corresponds to the number of sections of the difference curves in each experiment. The results show that the length of the vectors characterizing the difference curves decreases as the concentration of the analyzed organic matter decreases. In the limit, the curve visualizing organic matter with zero concentration takes the form of a circle, which indicates that there are no deviations from the stripping voltammogram of the electrochemical test system. Therefore, it can be concluded that the electrochemical test system can be certainly used for determining the concentration of organic compounds, producing quite reliable estimated results. This conclusion is confirmed by comparing the vector representation of analytes with the vector representations of organic substances of different concentrations, which constitute the database containing the results of experimental studies. Such a comparison is given in the form of a histogram reflecting the degree of proximity of the vector representation of the analyzed organic matter to substances from the database based on an estimate of Euclidean distances between the corresponding multidimensional vectors

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