Industrial wastewater from pharmaceutical production may contain organic solvents, catalysts, additives, by-products, raw materials, and active pharmaceutical substances, which presents serious difficulties for their processing.
The ease of spreading drug contamination in water bodies, the negative impact on hydrobiotite and, finally, the possibility of ingress of medicinal substances and intermediates in drinking water suggest that water contamination with drugs is the most dangerous. All this explains the special attention to the problem of water pollution by pharmaceutical substances, on which many countries of the world are concentrated. Once in the environment, pharmaceutical substances may undergo certain changes under the influence of both biotic and abiotic factors. As a rule, medicinal substances undergo degradation, losing their original activity. However, a number of compounds are not only resistant to natural destruction, but also able to change their activity with the formation of physicochemical transformants that represent a potential danger to living organisms and humans.
Electrochemical methods of analysis, in particular, voltammetry, are widely used to determine the content of various organic substances for environmental monitoring. Along with the indisputable advantages of the method, there are certain limitations on its use in analytical laboratories. In most cases, when determining the number of organic substances, a mercury-film is used as a working electrode. The main disadvantage of using this type of electrodes is the toxicity of mercury; therefore, the search and development of new selective mercury-free electrodes is an important task. The analysis of the literature and the conducted studies show the promising application of organic modifiers on various carbon substrates (glassy carbon, impregnated graphite) in the analysis of environmental objects using the methods of anodic inversion, adsorption, and cathode voltammetry.
We have conducted studies on the choice of operating conditions for the voltammetric determination of a number of medicinal substances, on the basis of which methods for the quantitative chemical analysis of air, water and soil samples for the content of these substances will be metrologically certified.
Using the new class of tosylate salts, arediazonium (ADT), organo-modified graphite and glassy carbon electrodes were first proposed for determining selected drugs, various factors were studied (time and method of contact, concentration of tosylate salts, arediazonium, etc.), and a technique for modifying the electrode for definitions of pharmaceutical substances, such as: halonal (5 – ethyl – 5-phenyl-I-o-fluoro-benzoylbarbituric acid), halodif (1 - [(3-chlorophenyl) (phenyl) methyl] urea) and meldonium (3- ( 2.2 , 2-trimethylhydrazine) propionate).
The surface of the modified working electrode was studied by probe microscopy, it was determined that when the modifier concentration was 10 mg / dm3 and the electrode exposure time was 5-7 seconds, an ensemble ultramicroelectrode system was formed on the surface, which increases the sensitivity of the test substances. ADTs of various structures were considered as modifiers: without a substituent, with a carboxyl, amino, and nitro substituent. The choice of a specific modifier (namely, a substituent in the structure of areadiazonium salt) depends on the chemical structure of the analyte. It has been established that when modifying an ADT electrode without a substituent for determining meldonium and halodif, it is more preferable in view of the highest sensitivity and reproducibility, whereas for barbituric acid derivatives (halo), the use of a glassy carbon electrode modified with ADT with a carboxyl substituent is proposed.
In the future, it is assumed the use of organo-modified electrodes to expand the range of defined organic substances, including those used as medicinal.
|Affiliation of speaker||Tomsk Polytechnic University|
|Position of speaker||ведущий научный сотрудник|
|Publication||Journal of Cleaner Production|