Romany Vassell is an undergraduate BSc (Hons) Chemistry student from the University of Surrey. She has completed 2 years of her degree and is on a 12-month industrial placement at the British Geological Survey, in the Inorganic Geochemistry (IG) facility of Keyworth, Nottingham. Here, Romany tells us a little about her experience...
The current stage of my project involves assessing the relative recovery of various As species sampled by microdialysis. A concentration of 100 µg kg-1 of each As solution is sampled at five flow rates, ranging from 1 to 10 µL min-1. This enables the efficiency of the semi-permeable membrane, the mobility of As species and flow rate of DI to be determined before analysis is conducted in soil solutions. A sample volume of 300 µL is collected (the time this takes depends on the flow rate, which can range from 30 minutes to 5 hours!). This limited sample volume would be a minor draw-back, but with precise analysis by HPLC-ICP-MS, this isn’t a problem.
I have thoroughly enjoyed the research and practical elements of this project, of which I will present the results to my university in September. Microdialysis is a fascinating technique and I am excited to see the scope of what this can achieve. I am keen to develop my knowledge in geochemistry after my undergraduate degree and hope to be able to use this technique again in future research.
Through the Hercules Sports and Social Club (HSSC) at BGS, I have attended events such as go-karting and watching the Nottingham Panthers play at my very first ice-hockey game. This was also a chance to interact with staff from other departments to understand what else goes on at BGS!
I am immensely grateful to the IG team and the support and guidance I have received during my time here. It has been an amazing experience to work in a team where the students are highly valued and given real responsibilities. I have had the opportunity to work with and form lasting friendships with students from the UK, India, Canada and Australia.
Acknowledgements:
Elliott Hamilton, Dr Olivier Humphrey, Dr Michael Watts
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| Romany with the ICP-QQQ |
I arrived at the British Geological Survey in July 2019 to commence a year's chemistry placement to support my degree. Alongside learning general lab tasks, my primary role is to operate the Agilent 8900 Triple Quadrupole Inductively Coupled Plasma-Mass Spectrometer (ICP-QQQ). The ICP-QQQ is a vital instrument in the inorganic chemistry facility and can be used for fast and robust multi-elemental analysis of various sample matrices such as water, urine, blood, digested soils and vegetation.
During my placement I’ve had the opportunity to undertake a specialised research project using the ICP-QQQ, which involves using microdialysis (MD) to measure in-situ soil arsenic (As) dynamics. This is a novel technique in soil science, contrary to its previous use in brain tissue to sample neurotransmitters.
Arsenic arises in the environment through volcanic activity and can be present in drinking water. The World Health Organisation (WHO) limits this zero-tolerance carcinogen in drinking water to 10 micrograms per kilogram (10 µg kg-1) however in countries such as Bangladesh, due to contaminated drinking wells and paddy fields, arsenic levels can often exceed this. In rice cultivation for example, the flooding of paddy fields to increase yield and suppress weed growth creates anoxic conditions, reducing soil-bound arsenate As(V) to its more mobile form arsenite As(III). Consequences of this arsenite in water include cancers of the skin, liver, bladder and kidneys, so it is vital to understand in situ As dynamics.
Microdialysis is a minimally invasive technique that can be used to investigate short-term trace element dynamics with real time temporal resolution. This requires a small probe with a semi-permeable membrane to be inserted into a soil solution, with sampling occurring at specified time intervals. This achieves greater resolution when compared to typical soil sampling methods. Multiple probes can also be inserted to sample at a specific soil depth for spatial resolution. Deionised water (DI) is forced through the probe via a syringe pump at a specified flow rate (µL min-1) through the inlet tube (see Figure 2) and down through to the semi-permeable membrane. Dissolved arsenic species can then diffuse from the soil solution, through the semi-permeable membrane and then pumped out via the outlet tube, and subsequently collected in a vial. They can then be analysed by High-Performance Liquid Chromatography to separate and identify the arsenic species coupled to ICP-MS to determine the concentrations of species.
During my placement I’ve had the opportunity to undertake a specialised research project using the ICP-QQQ, which involves using microdialysis (MD) to measure in-situ soil arsenic (As) dynamics. This is a novel technique in soil science, contrary to its previous use in brain tissue to sample neurotransmitters.
Arsenic arises in the environment through volcanic activity and can be present in drinking water. The World Health Organisation (WHO) limits this zero-tolerance carcinogen in drinking water to 10 micrograms per kilogram (10 µg kg-1) however in countries such as Bangladesh, due to contaminated drinking wells and paddy fields, arsenic levels can often exceed this. In rice cultivation for example, the flooding of paddy fields to increase yield and suppress weed growth creates anoxic conditions, reducing soil-bound arsenate As(V) to its more mobile form arsenite As(III). Consequences of this arsenite in water include cancers of the skin, liver, bladder and kidneys, so it is vital to understand in situ As dynamics.
Microdialysis is a minimally invasive technique that can be used to investigate short-term trace element dynamics with real time temporal resolution. This requires a small probe with a semi-permeable membrane to be inserted into a soil solution, with sampling occurring at specified time intervals. This achieves greater resolution when compared to typical soil sampling methods. Multiple probes can also be inserted to sample at a specific soil depth for spatial resolution. Deionised water (DI) is forced through the probe via a syringe pump at a specified flow rate (µL min-1) through the inlet tube (see Figure 2) and down through to the semi-permeable membrane. Dissolved arsenic species can then diffuse from the soil solution, through the semi-permeable membrane and then pumped out via the outlet tube, and subsequently collected in a vial. They can then be analysed by High-Performance Liquid Chromatography to separate and identify the arsenic species coupled to ICP-MS to determine the concentrations of species.
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| Figure 2 - Schematic of MD probe (left) and enlargement of the semi-permeable membrane (right). |
The current stage of my project involves assessing the relative recovery of various As species sampled by microdialysis. A concentration of 100 µg kg-1 of each As solution is sampled at five flow rates, ranging from 1 to 10 µL min-1. This enables the efficiency of the semi-permeable membrane, the mobility of As species and flow rate of DI to be determined before analysis is conducted in soil solutions. A sample volume of 300 µL is collected (the time this takes depends on the flow rate, which can range from 30 minutes to 5 hours!). This limited sample volume would be a minor draw-back, but with precise analysis by HPLC-ICP-MS, this isn’t a problem.
My project aside, I was fortunate enough to attend the Lab Innovations exhibition in October 2019 at the NEC in Birmingham. This was a brilliant opportunity, allowing me to familiarise myself with the latest advancements in laboratory equipment and improve my networking skills.
One of the highlights so far has been volunteering at the BGS Open Day in October 2019. This was a fun and interactive event aimed at both children and adults to encourage and inspire them to take up careers in geoscience. Alongside my student colleagues, we conducted several experiments such as 'Elephant's Toothpaste' – which involves the decomposition of hydrogen peroxide catalysed by potassium iodide. With the addition of dishwashing detergent, a large shooting foam (just like an elephant’s toothpaste…) is produced – to the joy of everyone watching!
One of the highlights so far has been volunteering at the BGS Open Day in October 2019. This was a fun and interactive event aimed at both children and adults to encourage and inspire them to take up careers in geoscience. Alongside my student colleagues, we conducted several experiments such as 'Elephant's Toothpaste' – which involves the decomposition of hydrogen peroxide catalysed by potassium iodide. With the addition of dishwashing detergent, a large shooting foam (just like an elephant’s toothpaste…) is produced – to the joy of everyone watching!
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| Figure 3: (from left to right): Romany, Stephanie, Sahil and Alastair at Teamworks go-karting |
Through the Hercules Sports and Social Club (HSSC) at BGS, I have attended events such as go-karting and watching the Nottingham Panthers play at my very first ice-hockey game. This was also a chance to interact with staff from other departments to understand what else goes on at BGS!
I am immensely grateful to the IG team and the support and guidance I have received during my time here. It has been an amazing experience to work in a team where the students are highly valued and given real responsibilities. I have had the opportunity to work with and form lasting friendships with students from the UK, India, Canada and Australia.
Acknowledgements:
Elliott Hamilton, Dr Olivier Humphrey, Dr Michael Watts
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