Determination of surfactants in environmental samples

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Title: Determination of surfactants in environmental samples
Author: Lehtonen, Markus
Contributor: University of Helsinki, Faculty of Science
Publisher: Helsingin yliopisto
Date: 2019
Language: eng
Thesis level: master's thesis
Discipline: Analyyttinen kemia
Abstract: We humans utilise many kinds of chemicals, some of them are safe to use and some of them are dangerous to use. There are chemicals that fall into grey area in the terms of safety. Surfactants are one of them. They are used abundantly and they find their ways to the environment. It is an established fact that surfactants can more or less hinder normal functions of cells, and in the worst cases can cause cell deaths. Despite of this, it is not completely understood what harm surfactants can do to the living organisms in the environment. We live and work in houses that are cleaned with washing chemicals and surfactants. Recently, surfactants were supposed to exist in indoor air, and new studies prove this hypothesis. Literature explains that there might be the possibility that surfactants can adsorb into aerosols. However, analysis methods capable to be used directly for determination of surfactants in aerosol condensate samples are not available. In this M.Sc. thesis a new surfactant determination method was developed with capillary electrophoresis using UV detection and tetraborate complex formation. First surfactant determination methods, found from the literature for environmental samples were reviewed and described in this M.Sc. thesis. Then their suitability for experimental studies was evaluated. Among many options, capillary electrophoresis coupled with ultraviolet detection was selected. The method was developed for determination of didecyldimethylammonium chloride (DDAC) and polyethylene glycol monoalkyl ether (Genapol X-80), which are representatives of cationic and nonionic surfactans, respectively, and represent the surfactants in cleaning chemicals. In the experimental work method development was focused on composition of the electolyte solutions, since they played an important roles in separation and sensitivity of the analytes. First Tricine was selected for electrolyte, because it provided the best responses in the preliminary tests. However, in the later studies it, unfortunately, proved to be unsuitable for the determination of cationic and nonionic surfactants. Therefore, in accordance with published literature tetraborate electrolyte was chosen. As application studies, we demonstrated that the studied surfactants are present in water vapour by analysing seperately DDAC and Genapol X-80 in collected water condensates by laboratory scale piloting tests.The developed method was also applied to authentic samples of indoor water condensates and washing solutions that were collected from two elementary schools with air quality issues. Surfactants were detected in these samples too.

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