Tothill, Ibtisam E.Newman, Jeffrey D.Kadara, Rashid2020-02-202020-02-202004-01http://dspace.lib.cranfield.ac.uk/handle/1826/15154The work presented in this thesis was concerned with the development of single-use drop-on sensors incorporating a three-electrode configuration (graphite carbon- working electrode, carbon-counter electrode and silver/silver chloride - reference electrode) for on-site detection of toxic heavy metals in various environmental matrices. The fabricated three-electrode configuration system was coupled with square-wave anodic stripping voltammetry (SWASV) or constant current stripping chronopotentiometry (CCSCP) in order to provide a means of a relatively inexpensive on-site detector for trace levels of lead (II), copper (II) and cadmium (II). Detections and determinations of these metals were carried out on bare screen-printed carbon electrodes (SPCEs), mercury film SPCE, bismuth film SPCE and SPCEs modified with Nafion, 2,5- Dimercapto-1, 3, 4- thiadiazole (DMTD), bismuth oxide (Bi₂O₃) and polyethyleneimine (PEI) using the optimised procedures developed for measurements. With the optimised working conditions, the results obtained indicate that the screen-printed electrochemical sensors are sensitive and reproducible enough for the CCSCP and SWASV determination of lead, copper and cadmium in the microgram per litre - milligram per litre range. Limits of detection below 20 µg I¯¹ were estimated for the trace metal detection of lead, copper and cadmium on both the bismuth and mercury film electrodes. For the bare SPCE, detection limits of 35, 45 and 59 µg I¯¹ were obtained for lead, cadmium and copper detection using CCSCP. The reproducibility of the measurements, which also contributed to the interest in developing the electrochemical sensing devices for metal ions, was below 15 % for the bare SPCE, bismuth film SPCE, and mercury film SPCE. Modifications of SPCEs with an ion-exchanger (Nafion) and a complexing agent (DMTD) provided means of increasing the sensitivity of stripping response obtained at the bare SPCE. Detection limits of 20 and 22 µg I¯¹ were estimated for lead (II) measurements at the Nafion modified SPCE and at the screen-printed DMTD modified electrode, respectively. The application of the various electrodes to real samples is demonstrated and proved successful for both water and soil extracted samples including in situ measurements at a contaminated site.en© Cranfield University, 2015. All rights reserved. No part of this publication may be reproduced without the written permission of the copyright holder.Thesis