45
Following sample introduction onto the GC column, analytes are transferred through the column to the detector by the mobile phase (carrier gas), and separated according to their interaction with the column stationary phase and volatility. Analytes elute off the column and fl ow through the transfer line into the fl ow cell, where photons of light from a deuterium lamp are absorbed by the analytes and their spectra (125 - 430 nm) are recorded by a charged coupled device (CCD) detector (see Figure 3). Given nearly all molecules have a unique electronic structure (and absorption cross-section), this can provide a highly specifi c spectral ‘fi ngerprint’, enabling the identifi cation of analytes through comparison with reference spectra.
• Quick and robust analyte classifi cation using post-acquisition spectral fi lters, algorithms, regression statistics for spectral matching and a retention index.
• Fast scanning capability (data acquired up to 77 Hz) - enables good sampling statistics per GC peak, offering reliable and accurate quantitation using a simple linear relationship (Beer-Lambert Law) to pg sensitivities.
• Complementary detection to MS - can measure volatile analytes not amenable to MS and distinguish some isomers and isobaric compounds.
Applications
Figure 3: Cross-sectional diagram of the VUV detector showing the application of light to the fl ow cell, with the acquisition of subsequent spectra and chromatogram (image published with permission from VUV Analytics).
Key ‘take aways’ and benefi ts of the technologies Bead Beating Homogenisation
• Wide range of accessories and homogenising matrices facilitate processing sample sizes of <0.5-50 mL.
• Is extremely quick compared to rotor stator homogenisation, operates with tubes or well- plates for higher sample throughput. • Cryo-cooling for thermally labile analytes to ensure analyte preservation.
Multi-modal sample introduction
• Variety of sample introduction modes for different sample matrices - improved laboratory versatility (TD/Pyrolysis/LVI).
• Low thermal mass allows fast and uniform heating for applicability up to C100. • Inert surfaces minimise degradation of labile components.
VUV
• ‘Universal’ detector capable of discriminating highly similar analytes when in the gas phase (including structural isomers).
• Highly repeatable and additive spectra - enables molecular identifi cation (including those that co-elute) by searching against reference spectra, and operation of faster, higher- throughput chromatographic methods without fully separating analytes.
Despite the primary usage of VUV detection for petrochemicals, and the initial remit of this installation in addressing environmental-sector challenges, its applicability to a broader range of sample materials, volatile and semi-volatile chemistries, can provide enhanced analysis of those measured across many sectors. For example, monitoring approaches within environmental, biotech, pharma, fi ne chemical, materials manufacturing, forensic and clinical sectors can involve laborious protocols to displace analytes from sample materials for detection, and often fail to discriminate similar (isomeric) substances. Given substance activity (and toxicity) is dependent on molecular shape (e.g. pharmaceuticals, pesticides, polyaromatic hydrocarbons, polychlorinated biphenyl (PCB) pollutants), these limitations pose a signifi cant environmental and public health risk. Therefore, by better releasing substances sorbed to materials, and distinguishing structural isomers and co- eluting species, this installation offers signifi cant benefi t for a diverse set of application areas. Specifi cally, this can enhance monitoring for the design of safer, cleaner and more accurate treatments, technologies, recycling/re-use and manufacturing processes, for more effective healthcare, resilient and sustainable CE [1-6].
To deliver this agenda, the installation will:
1) actively seek industry, government and academic collaboration to explore new application areas for a CE and beyond, to fully exploit capacity, capability and impact, 2) support users continuous professional development (CPD) in the technologies, and 3) assist in the expansion of the VUV spectral database for ease of future substance detection.
For further information on the technology installation and potential collaborative projects, please contact the capability lead, Dr Ruth Godfrey (
a.r.godfrey@swansea.ac.uk).
Acknowledgements
The authors gratefully acknowledge the support from industry collaborators, and funding from Welsh Government in helping to establish this capability.
1. WG Beyond Recycling: a strategy to make the circular economy in Wales a reality. 2. Well-being of Future Generations Act (WFGA). 3. Environment (Wales) Act, Natural Resources Policy. 4. WG Prosperity for All: the national strategy. 5. UKRI The Business of the Environment. 6. HMG UK Industrial Strategy
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