Abstract
M.Sc. (Chemistry)
Personal care products (PCPs) refer to chemicals used as active ingredients in cosmetics, fragrances, shampoos, toothpastes and soaps which are believed to have endocrine disrupting potential. Personal care products are currently categorised as emerging pollutants, since there are no regulations put in place on their allowed levels in the environment. They have been a focus of research since the 1990s as a result of their constant introduction to the environment. Personal care products are either excreted or washed off after use. These pollutants enter the environment via different paths including run off from water bodies, leaking septic tanks and the release of waste water effluents, hence the release of these chemicals into the environment is constant. For this reason, there is a need to monitoring the presence and levels of these chemicals. In addition, emerging pollutants are present in the environment in trace or ultratrace levels or incorporated in complex matrices which makes it difficult to detect them directly using analytical detection techniques. Therefore, the aim of this work was to develop different sample preparation methods to address some of the shortcomings of conventional analytical detection techniques (such as Ultraviolet-Visible spectrophotometry and high pressure liquid chromatography) encountered during the analysis of personal care products. To achieve the aim of the study, three different sample techniques were explored: solid phase extraction, vortex assisted supramolecular solvent based microextraction and ultrasound assisted solid phase nanoextraction.
In the first experimental section, a solid phase extraction (SPE) procedure using commercially available ion exchange resin as an adsorbent was evaluated for preconcentration of benzophenone and sulisobenzone in wastewater samples prior to UV-Vis spectrophotometric determination. The solid phase material used displayed attractive factures such as selectivity, wide chemical stability, wide operation pH ranges and predictable solid surface/ analyte interactions. Under optimised conditions, the SPE significantly improved the limits of detection (0.15-0.28 μg L-1) and limits of quantifications (0.50-0.93 μg L-1) of the UV-Vis spectrophotometry towards the detection of the selected analytes. In addition, the developed method had relatively wide dynamic linear range, high precisions (intra-day and inter-day) and satisfactory recoveries (>95%).
The second experimental work reports the development of a vortex assisted supramolecular solvent based microextraction combined with UV-Vis spectrophotometry...