Development a portable system for monitoring chemicals pollutants in environmental river water samples

Oiaidha, Zeid Osama

Abstract

Environmental pollution has become a serious problem around the world that influences all living organisms directly and indirectly. The growing world population is accompanied by developments in several fields including industry, agriculture and technology. All of this leads to increase in the rate of pollution of air, soil and water and these needs to be monitored. The detection of pollutants in the environmental sample is challenging due to the complex sample matrix and often trace level concentration of the analytes. Currently, the analysis is commonly carried out by high-cost sophisticated instrumentation and therefore the development of portable systems capable of detecting chemical pollutants in environmental samples with high selectivity and sensitivity has become urgent. This work aimed to develop a microfluidic system that combined pre – concentration and detection of a mixture of organic pollutants in river water sample.
The pre – concentration step utilised solid phase extraction (SPE), in which a modified silica monolith column by octadecyl carbon chain (C18) acted as the sorbent. The silica monolith was selected due to its bimodal structure that offered high surface area while ensuring a low backpressure when liquids were pumped into it. In addition, the silica surface could be easily modified, with a suitable functional group such as (C18) that increase the interaction between the analytes and sorbent surface. In addition, the silica monolith offered high stability with several organic solvents.
In this work the silica monolith was modified by octadecyl silane C18 (reverse- phase) to pre – concentrate the mixture of organic compounds involved (progesterone, estradiol and benzo (a) pyrene) from river water samples. The pre - concentration process of the mixture of analytes were determined in river water sample with HPLC-UV detection where the concentration of the sample (100 mL) at loading step was 1 μg mL-1 and after complete the elution step (1 mL) the concentration of analytes were jumped to 51, 62 and 60 μg mL-1 for estradiol, progesterone and benzo (a) pyrene respectively. The effective of extraction and pre – concentration process of organic pollutants from river water sample is improved the limit of detection (LOD) and avoided of interference of the detection method.
To achieve high selectivity, an immunoassay was evaluated with both electrochemistry and chemiluminescence detection. These detection methods were selected due to their high sensitivity, selectivity and the simple instrumentation required. A heterogeneous assay was carried out with an antibody that was modified with a ferrocenecarboxaldehyde tag. The antibody was immobilised onto an indium tin oxide (ITO) electrode using electrochemistry through a phenylamine group on the ITO electrode surface. A fast and sensitive multiplexed detection method was developed with square wave voltammetry (SWV) with limits of detection (LOD) of 28.74, 68.53 and 60.48 pg mL-1 for progesterone, estradiol and benzo (a) pyrene respectively in river water matrix. With luminol chemiluminescence detection the LODs values were decreased, where this technique achieved LOD at 20.5, 12.95 and 13.97 pg mL-1 for progesterone, estradiol and benzo (a) pyrene respectively also in river water matrix.
Two different designs of microfluidic system device were then fabricated with the aim of combining all the steps in one device, Cyclic olefin copolymer (COC) polymer was used to make the first design, while the second design was made from glass.

Citation

Oiaidha, Z. O. (2016). Development a portable system for monitoring chemicals pollutants in environmental river water samples. (Thesis). University of Hull. Retrieved from https://hull-repository.worktribe.com/output/4224046

• Thesis Type: Thesis
• Deposit Date: Mar 24, 2022
• Publicly Available Date: Feb 24, 2023
• Keywords: Chemistry
• Public URL: https://hull-repository.worktribe.com/output/4224046
• Additional Information: Department of Chemistry, The University of Hull
• Award Date: Aug 1, 2016