State-of-the-art in the analysis of complex environmental matrices
Roger Reeve
rgrreeve@gmail.com
ECG Bulletin July 2023
rgrreeve@gmail.com
ECG Bulletin July 2023
The fifth meeting in this biennial series discussed new developments in chromatographic, spectroscopic, mass spectroscopic, and data processing methods for analysis of complex atmospheric, aqueous, and solid environmental samples.
The meeting was organised jointly by the Environmental Chemistry Group (Caroline Gauchotte-Lindsay, Roger Reeve), the Separation Science Group and the Water Research Forum (Graham Mills).
The meeting was organised jointly by the Environmental Chemistry Group (Caroline Gauchotte-Lindsay, Roger Reeve), the Separation Science Group and the Water Research Forum (Graham Mills).
This year, the meeting had a new format, with four lunchtime webinars held fortnightly. Two speakers discussed topics in related areas, before discussion. This new format proved highly successful, with over 50 attendees at each session, the numbers slowly increasing during the course of the series.
The series was started by Professor Barbara Kasprzyk Hordern (University of Bath) with ‘Wastewater based epidemiology and One Health’. One Health is aimed at a holistic understanding and management of public and environmental health. The case study investigation looked at a whole catchment area on the river Avon, with five wastewater treatment plants and five towns/cities. It included monitoring 141 compounds of emerging concern. 75% of the population of 1.14 M was covered. Throughout the region, each person contributes around the same amount of chemicals per day (12 mg/day), but individual chemicals correlate with different populations. Temporal differences are also detected. Chemical concentration profiles can indicate a population’s overall health. They may also indicate occupational exposure. Continuing work is developing means to identify specific chemicals and proteins that act as public health biomarkers.
The second speaker, Dr Brett Sallach (University of York), discussed ‘Understanding the transport and fate of chemical pollutants in agroecosystems’, focussing on the use of wastewater in agriculture with the possible uptake of pollutants by plants. Hydroponic experiments simplified the initial investigations by removing the effect of soil type. It was shown that bioconcentration correlated better with water analysis than by soil type. Machine learning was then used to correlate uptake with chemical structure. Single cell mass spectrometry (SCMS) is used to identify chemical residues and their metabolites in plants (see ECG Bulletin, July 2022, pp 12-13).
The second speaker, Dr Brett Sallach (University of York), discussed ‘Understanding the transport and fate of chemical pollutants in agroecosystems’, focussing on the use of wastewater in agriculture with the possible uptake of pollutants by plants. Hydroponic experiments simplified the initial investigations by removing the effect of soil type. It was shown that bioconcentration correlated better with water analysis than by soil type. Machine learning was then used to correlate uptake with chemical structure. Single cell mass spectrometry (SCMS) is used to identify chemical residues and their metabolites in plants (see ECG Bulletin, July 2022, pp 12-13).
Two weeks later, Professor Jacqui Hamilton (University of York ) began the second session with her presentation: ‘Are emissions from green spaces important for urban air quality? Using high resolution methods to understand the interaction of biogenic emissions with air pollution in cities’. Reversed phase ultrahigh performance liquid chromatography with Orbitrap MS (UPLC with Orbitrap MS) was used to monitor the Beijing atmosphere over an extended period. The organic fraction is highly complex. The biogenic volatile organic compound (VOC) emissions impact the formation of ozone and secondary organic aerosol (SOA) formation.
Dr Leon Barron (Imperial College) followed with his presentation ‘Rapid monitoring and risk assessment of chemicals of emerging concern at scale.’ The need for rapid monitoring is necessary for schemes covering several hundred sites and potentially over a hundred analytes. The method used was direct injection into a liquid chromatograph with tandem mass spectroscopy (LC/MS/ MS). The London catchment was monitored over a lockdown period. Sampling itself was achieved using citizen scientists who added local knowledge for the most ideal sampling sites. A separate investigation area was the development of a 3D printed passive sampler, providng a surrogate and more rapid method for analyte uptake by invertebrates.
Dr Leon Barron (Imperial College) followed with his presentation ‘Rapid monitoring and risk assessment of chemicals of emerging concern at scale.’ The need for rapid monitoring is necessary for schemes covering several hundred sites and potentially over a hundred analytes. The method used was direct injection into a liquid chromatograph with tandem mass spectroscopy (LC/MS/ MS). The London catchment was monitored over a lockdown period. Sampling itself was achieved using citizen scientists who added local knowledge for the most ideal sampling sites. A separate investigation area was the development of a 3D printed passive sampler, providng a surrogate and more rapid method for analyte uptake by invertebrates.
In webinar three, Dr David Scurr (University of Nottingham) introduced us to ‘Reducing combustion emissions with secondary ion mass spectrometry’. Here, he discussed how combustion deposits in diesel and petrol engines can reduce fuel efficiency. Analysis used Time of Flight (TOF) and Orbi Secondary Ion Mass Spectrometry (OrbiSIMS). Ion beams are fired at a specific area of the sample, and a structural depth profile built up. As well as the inorganic components, organic products from the lubricating oil may be found and complex polyaromatic hydrocarbons, their structure increasing in complexity with depth in the deposit. The presence of the complex molecules was confirmed using MALDI (matrix assisted laser desorption/ionisation).
Dr Nicholle Bell (University of Edinburgh) then spoke on ‘Using NMR and FT-ICR-MS to tackle natural and man-made mixtures in our changing environment. A journey from peatlands to drinking water.’ About 80% of UK’s peatland is damaged by drainage. Major attempts are being made to reverse this. Can the changes be monitored analytically as the peat changes from anoxic waterlogged to dry conditions and subsequent restoration?
Natural organic matter contains molecules in the range 200-500 Da, with many -OH and -COOH side groups. Peat core samples, water and NaOH extracts and pore water were taken. Solid state NMR of core samples showed changes of the average number of functional groups with depth, indicating a chemical correlation. Fourier Transform–Ion Cyclotron Resonance Mass Spectrometry (FT-ICR-MS) may be used for solid and liquid samples and so to compare the two phases and produce structural information. Multidimensional NMR (1H, 13C and 15N) was also used. Specific structures were identified in the water samples. The techniques were then used in a separate investigation to determine structures found in the complex mixture produced when water, after several stages water treatment (and still containing residual organic material), is chlorinated.
Dr Nicholle Bell (University of Edinburgh) then spoke on ‘Using NMR and FT-ICR-MS to tackle natural and man-made mixtures in our changing environment. A journey from peatlands to drinking water.’ About 80% of UK’s peatland is damaged by drainage. Major attempts are being made to reverse this. Can the changes be monitored analytically as the peat changes from anoxic waterlogged to dry conditions and subsequent restoration?
Natural organic matter contains molecules in the range 200-500 Da, with many -OH and -COOH side groups. Peat core samples, water and NaOH extracts and pore water were taken. Solid state NMR of core samples showed changes of the average number of functional groups with depth, indicating a chemical correlation. Fourier Transform–Ion Cyclotron Resonance Mass Spectrometry (FT-ICR-MS) may be used for solid and liquid samples and so to compare the two phases and produce structural information. Multidimensional NMR (1H, 13C and 15N) was also used. Specific structures were identified in the water samples. The techniques were then used in a separate investigation to determine structures found in the complex mixture produced when water, after several stages water treatment (and still containing residual organic material), is chlorinated.
The final webinar began with a talk by Dr Richard Cross (UK Centre for Ecology & Hydrology) on ‘Monitoring microplastics in the environment – experiences in detection and interpretation of microplastic contamination in increasingly complex media. Microplastics arise from plastic degradation and may also be fibres beds and pellets. We need to identify a correlation between size/shape and adverse properties. No one analytical technique can cover the complete size range, the lowest range being flow cytometry, then µ-FTIR (Fourier Transform Infra-Red Spectroscopy), then ATR-FTIR (Attenuated Total Reflectance FTIR). Sampling itself may degrade the sample and data analysis affects the final result. The large differences found in literature results may be due to these considerations. Common principles and reporting requirements are needed to allow data from multiple sources to be combined and interpreted correctly.
Dr Mark Perkins (Anatune) finished the series speaking about ‘Rapid analysis of soils and water using selected ion flow tube mass spectrometry (SIFT-MS)’. The technique is useful for small volatile organic molecules and some inorganic gases. It is transportable and has been used for field applications such as fenceline monitoring of industrial plants. Another advantage is its speed, several times faster than gas chromatography/mass spectroscopy (GC-MS) for volatile organics. Thermal desorption SIFT-MS is another application used for plastics or any other material which can produce volatile organics.
Dr Mark Perkins (Anatune) finished the series speaking about ‘Rapid analysis of soils and water using selected ion flow tube mass spectrometry (SIFT-MS)’. The technique is useful for small volatile organic molecules and some inorganic gases. It is transportable and has been used for field applications such as fenceline monitoring of industrial plants. Another advantage is its speed, several times faster than gas chromatography/mass spectroscopy (GC-MS) for volatile organics. Thermal desorption SIFT-MS is another application used for plastics or any other material which can produce volatile organics.
It seems fitting that, in a symposium series based throughout on ‘New Developments’, we should investigate using a new form of presentation. The overwhelming opinion was that the format and presentations were successful. If you missed any of these talks, or want to revisit them, they can be found on-line at:
https://www.youtube.com/playlist?list=PLLnAFJxOjzZszpgJd_6Zhl-KFNZ-67IFL
https://www.youtube.com/playlist?list=PLLnAFJxOjzZszpgJd_6Zhl-KFNZ-67IFL
