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Project Highlights:

  • Explore critical questions around unmeasured reactivity in the atmosphere
  • Development of a novel analytical technique
  • Impacts for atmospheric composition and air quality, health and climate

Volatile organic compounds (VOCs) are found throughout the earth’s atmosphere. They are emitted naturally by living systems, but a wide range of VOCs are also emitted from man-made sources and these can have a damaging effect on the environment and on human health. Chemical plants, oil refineries, gas platforms, vehicle and aircraft emissions, are all major sources of atmospheric VOCs. VOCs are also emitted by numerous consumer products such as paints, solvents, glues, newspapers, and cosmetics.

The number, amount, influence, chemistry and fate of organic compounds in the atmosphere are generally unknowns. It has been estimated that we cannot account for the loss of approximately half the non-methane organic carbon entering the atmosphere [1] but emission studies suggest that > 104 organic compounds are present [1]. Owing to ambiguities in assignment, conventional analytical methods struggle to identify more than ca. 500. Since the number of organic compounds in the atmosphere far exceeds the number of measured species, the development of measurement methodologies capable of dealing with a large range of organic compounds is a key challenge in atmospheric chemistry.

It is also important to establish the impact of these unmeasured organic compounds on a number of key processes around oxidative capacity and secondary organic aerosol formation. This PhD project aims to detect and quantify these previously unmeasured VOCs and to assess their atmospheric impact

Schematic representation of the conversion of urban atmospheric air sample to a measure of total volatile organic content


The key element of this project is to develop new instrumentation to measure total non-methane carbon (TVOC) in the urban atmosphere using switchable reagent ion PTR-ToF-MS (proton transfer reaction time-of flight mass spectrometry) [2-4]. TVOC is a quantity that can be related to this missing fraction of organic compounds. PTR-MS allows high sensitivity and mass resolution along with fast temporal measurement of a wide range of VOCs. Using a modification of the ion chemistry employed within this technique it can be used to determine the total carbon amount present in an air sample [2] and hence the missing fraction.

The student would be involved in the end-to-end development of the technique via:

  1. Laboratory development and calibration of a total VOC (TVOC) system
  2. Deployment of system in a urban atmosphere for measurement of TVOC
  3. Analysis of data to assess TVOC loading against fully speciated VOC measurements.
  4. Assessing correlation of TVOC with oxidant load.

Training and Skills

CENTA students will attend 45 days training throughout their PhD including a 10 day placement. In the first year, students will be trained as a single cohort on environmental science, research methods and core skills. Throughout the PhD, training will progress from core skills sets to master classes specific to the student's projects and themes.

The project will provide training in atmospheric, analytical [2] and field science. The successful applicant will use of state-of-the-art research instrumentation for trace gas measurements and will interact with/pool their results with scientists using commercially-available air monitoring equipment at a newly-commissioned measurement station for air pollutants and atmospheric aerosol on the University of Leicester campus. There will be the opportunity for fieldwork and international travel.


Year 1 – Development, characterisation and calibration of PTR-ToF-MS system for the measurement of TVOC

Year 2 – Concerted measurement campiagns in urban/rural atmospheric conditions. Alongside TVOC measurements, full measurement of speciated VOC and total reactivity/oxidant prodcution.

Year 3 - Analysis of data from measuerments and comparison to model data. Identify any control of secondary aerosol formation and oxidative capacity.


Partners and collaboration (including CASE)

Prof. Paul Monks and his group research atmospheric chemistry. The collaborative team includes international partners in CSIRO Australia to provide an international context for the work. Collaborators on the supervision team from UBirm bring new technique development experience for oxidative capacity, oxidant production rates and advanced PTR-MS techniques.