Analysis of starting material enabled identifi cation of unreacted precursors through retention time matching and spectral comparison with authentic references. Importantly, alternative spectral bands allowed accurate quantifi cation of partially co-eluting impurities without method redevelopment (Figure 3). Together, these examples demonstrate that VUV detection delivers not only low limits of detection, but also increased analytical confi dence when monitoring complex reaction mixtures, residual solvents, water, and trace impurities.
Application in liquid
chromatography In liquid chromatography, detection is often constrained by the limited chromophoric properties of many analytes. Compounds such as aliphatics, lipids, polymers, amino acids, and certain excipients may exhibit weak or negligible absorbance above 200 nm, necessitating the use of alternative detection techniques such as RI, ELSD, or CAD or chemical derivatisation.
VUV detection extends absorbance-based detection into a spectral region where these compounds absorb more strongly, enabling direct, linear detection without the need for aerosol formation, solvent evaporation or chemical derivatisation.
Figure 6: The VUV spectrum of arginine and chromatographic detection by VUV and UV .
Figure 3: Comparative chromatograms by VUV (band 5, 9 and 10) vs FID detection.
Selectivity: Compound differentiation
and spectral fi ngerprinting Beyond sensitivity, VUV detection offers enhanced selectivity through compound-specifi c spectral signatures. Functionally analogous to a UV-PDA detector in liquid chromatography, VUV detectors enable peak purity assessment and method specifi city evaluation for GC applications. This capability is particularly valuable for complex samples such as multi-solvent formulations, crude reaction mixtures, pharmaceutical degradation studies, and fl avour and fragrance products.
In collaboration with a fl avour and fragrance manufacturer, a series of experiments was conducted using authentic standards alongside complex mixed samples. By building a library of reference spectra, impurities were identifi ed through combined retention time and spectral matching. The analysis further revealed that several peaks previously assumed to be pure actually co-eluted with known impurities, exposing limitations in the original method’s specifi city. These results demonstrate the ability of VUV detection to confi rm impurity identity, assess peak purity, and uncover co-eluting species, thereby improving method robustness and analytical confi dence (Figure 4).
* data processed in Openlab
To demonstrate the sensitivity gains achievable with VUV detection, 21 underivatised amino acids were analysed using detection at 190 nm (Figure 5). All amino acids exhibited measurable absorbance in the VUV region, underscoring the broad applicability of this approach for analytes traditionally considered UV-invisible.
The VUV spectrum of arginine is shown in Figure 6, where a pronounced increase in molar absorptivity is observed as the wavelength decreases into the VUV region. This translated directly into enhanced analytical sensitivity, with an approximately 80-fold improvement relative to conventional UV detection. These results illustrate how VUV detection combines the quantitative robustness and linearity of UV detection with substantially improved sensitivity and analyte coverage, expanding the scope of absorbance-based detection in liquid chromatography.
Conclusions
Vacuum ultraviolet detection represents a signifi cant advancement in chromatographic detection for both gas and liquid chromatography. By accessing a high- energy spectral region in which most organic compounds absorb, VUV detection delivers near-universal sensitivity while simultaneously providing chemically informative spectral data. In GC applications, this combination enables sensitive residual solvent analysis, improved impurity detection, peak purity assessment, and deconvolution of co-eluting species—capabilities that bridge the gap between non-specifi c detectors such as FID and more complex techniques such as mass spectrometry.
The extension of VUV detection into liquid chromatography further broadens its analytical impact. By enabling sensitive, linear absorbance detection for compounds with weak or absent chromophores, LC–VUV detection addresses longstanding limitations of conventional UV–Vis detection and reduces reliance on alternative detectors with inherent trade-offs. The ability to acquire full spectral information also supports improved method development, specifi city assessment, and impurity profi ling.
Figure 5: Chromatography of 21 amino acids detection with VUV at 190nm.
Collectively, these attributes position VUV detection as a versatile and complementary tool within modern chromatographic workfl ows. As analytical demands continue to shift toward more complex samples, tighter impurity control, and increased effi ciency, VUV detection offers a compelling balance of sensitivity, selectivity, and practicality. Its continued adoption in both GC and LC applications is likely to reshape detector selection strategies and expand the analytical capabilities available to chromatographers across a wide range of industries.
Acknowledgments
Figure 4: Peak purity and spectral matching for a fragrance sample.
The author would like to thank Dr. Sam Whitmarsh, Director of Analytical Science at Catsci Ltd, as well as Dan Driscol, Ollie Stacy, and Declan McMorrow of UVison Ltd, and Ryan Schonert of VUV Analytics for their valuable contributions and support throughout this work.
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VUV detection delivers near-universal sensitivity while simultaneously providing chemically informative spectral data
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