Electrochemical hydride generation and electrochemical accumulation for detection of hydride forming elements by atomic fluorescence spectroscopy

This is an extract of the research project. Simply click on “Apply on-line” above for an instant access to the complete version.

The project will focus on the detection and speciation of hydride forming elements such as arsenic, antimony or mercury at the levels encountered in marine systems and in other types of waters (e.g. groundwater, industrial effluents). An on-line electrochemical trapping system can achieve high preconcentration factor of the target analytes and offer well-controlled possibilities in selectively removing potential interferences before the detection step. Such trapping device requires a conductive material with a high surface area to accumulate significant amount of target analytes while avoiding saturation. The search for adapted nanomaterials, such as carbon nanotubes, coated or not with appropriate film (e.g. gold) will be tested.

Electrochemical hydride generation (EHG) is achieved by imposing a strong cathodic polarization at an electrode. Its efficiency strongly depends on the hydrogen overvoltage of that electrode material: materials with a high hydrogen overvoltage (e.g. Pb, Hg) are best suited but they might be prone to higher interferences than those materials (e.g Au, Pt) with low hydrogen overvoltage [3, 4]. It also strongly depends on chemical parameters such as the solution pH. In this project, we will test different materials for the hydride formation of As, Sb, Se and Hg and develop an optimised electrolytic cell [5]. This cell wil be used on-line with the electrochemically driven trapping device and the AFS for the detection of natural levels of hydride forming elements in natural waters, including seawater [6]. In both electrochemical compartments, the use of several nanomaterials (e.g. gold nanoparticles, graphene, carbon nanotubes) will be tested on-line and compared to the chemical hydride generation batch method. Efficiency, ease of use and longevity/robustness will be the prime objectives that PSAnalytical will assess when considering potential commercial applications.

The major part of the research project will be conducted at the University of Liverpool with a minimum period of 3 months to be spent at PSAnalytical, Kent (UK). The project will start with an extensive review of the literature on the electrochemical system used for separation/accumulation of target analytes as well as cathodic materials used for the EHG of hydride forming elements. Trapping devices will be developed and tested on-line with the batch chemical hydride generation while the EHG testing of arsenic, antimony and mercury (possibly including other elements if time allows) will be tested using various cathodic materials with a range of hydrogen overvoltage. Combination and coupling of the electrochemical trapping device with the EHG module and AFS detection is expected to lead to a powerful, sensitive, interference free, analytical method.

This is an exciting program of research with an industrial CASE partner. The project will benefit from Dr.Lopez-Sanchez’s expertise of nanomaterials (from synthesis to catalytic effects), from the newly developed MIF (Materials Innovation Factory - http://www.liv.ac.uk/materials-innovation-factory/) and from Salaun’s expertise of electrochemical devices. PSAnalytical is a world leading company specialized in the detection of metalloids in various difficult matrices, including seawater (http://www.psanalytical.com/). We are looking for a highly motivated PhD student with relevant experience in chemistry and/or material sciences. You will gain both academic and industrial experience to make your CV highly competitive for your next move. You will benefit from numerous training opportunities inherent to the Doctoral Training Partnership that join expertise from Liverpool, Manchester and the National Oceanographic Centre. You will be part of the third cohort of enthusiastic DTP PhD students and you will become not only an expert in your research area but also develop strong interdisciplinary skills through specific training programs, research seminars and the research environment of the School of Environmental Sciences, School of Chemistry or at PSAnalytical.