VUV Versus Industry

Taking (Molecular) Control

By Pierre Giusti, Molecular Separation & Identification Service Manager, and Gaelle Jousset, Gas Chromatography Laboratory Manager, Research & Development, TOTAL Refining & Chemicals, Normandy, France.

We work together on R&D in the analytical department to understand how analytical chemistry can better support the needs of the business. One mission within that overarching goal is seeking out and evaluating new technology that could be potentially useful. When it comes to utility, there is a real demand for (analytical) information at the point of need – for us, that means considering ways of shifting robust analysis out of research laboratories and into control labs.

Back in 2014, we met VUV Analytics at the PetroPhase conference in Galveston, Texas. The team was there to gather information about the needs of the petroleum industry from an analytical point of view. A connection was sparked when we realized that VUV detection could be a powerful tool for gaining molecular information without the complexity of mass spectrometry. The main advantage we saw was its potential to be used in our control laboratories. Most of our process optimization is based on macroscopic data (sulfur content, viscosity, density and so on). Why? Because gaining molecular information beyond what can be provided by GC separation and a non-specific flame ionization detector (FID) in the refinery is difficult – the analytical instrumentation required is typically too complex for the environment and requires data interpretation that cannot be directly plugged into the process optimization loop.

One of the main advantages of VUV detection for us appeared to be the ability to gain more specific molecular information on species with an instrument set up that shares the simplicity of FID.

Performance in the real world

Since October 2015, we have been evaluating the potential of the VGA-100 VUV detector. So far, the results are encouraging. Co-elutions that we know exist but cannot be identified with FID can be unraveled using VUV detection. Such information is very useful in refining process optimization – if it can be used in the control lab. We’ve also evaluated the VUV detector in terms of reproducibility and arrived at the specifications reported by VUV Analytics – and that makes it fit for our purpose and an improvement over current techniques being used in the control lab. It’s also very robust and easy to operate from a hardware point of view. We’ve performed zero maintenance (apart from changing the deuterium lamp) over nine months... In that regard, it’s actually an improvement over FID and built for process analysis.

Clearly, the next step is to find out how VUV detection can be moved out of the research lab and implemented in the control lab – and that means further simplification of data interpretation. Right now, VUV detection is not a ‘black-box’ – and nor was it originally designed to be – and therefore, it still requires the skill of an analyst to draw out relevant data. In control labs, data treatment needs to be more automated or at least greatly simplified for our application. We are very much enjoying working closely with the enthusiastic and ambitious team at VUV Analytics towards this goal and see great potential in VUV detection for PIONA analysis and beyond.

What are your first impressions of the VUV detector?

We have been working with the VUV detector at the university for about three months so far. Overall, we’re pleased with it. Data reproducibility is excellent, for example. It’s relatively new on the market, so there’s a learning curve for users and the team at VUV Analytics – I am sure users will do some ‘interesting’ things that they perhaps do not expect! But being an early adopter also has advantages and it’s great to have an analytical tool that genuinely offers something new to GC.

Can you comment on ease of use from an academic or industry point of view?

In academia, many researchers tend to focus more effort on either LC or GC. In industry, you’re likely to do both – and the step from working on LC with UV detection to GC with VUV detection is a relatively small one. At least, that was my impression. As for adoption in process or quality control environments, I think the sticking point is more likely to be with the level of experience with gas chromatography, which is already considered a little complex in certain routine environments. The VUV detector is straightforward – it’s GC use that might be more of a concern. I can imagine that the combination of a more user-friendly GC with VUV detection could be an attractive one...

And robustness?

There is only one replaceable part – the lamp. And importantly, it is very easy to tell when this part needs replacing by measuring the energy, which is governed by self-diagnosis. Consider mass spectrometry, where the source might steadily become contaminated, affecting performance – it may be difficult for a less experienced user to recognize that something is wrong or to know when to take action.

What are the instrumentation demands in routine quality control?

QC labs typically want a straightforward answer to the question: is the sample good or bad? Is it a green light or a red light? And I suspect that the VUV detector has some applicability in those kinds of decisions. If you use GC with flame ionization detection, you have to look to the chromatograms, find the right peak among many and then check it’s the correct peak based on retention times. If you have the added selectivity of VUV spectral information, it’s much easier to find the right peak and whether or not it’s below the limit. Reducing operator interpretation of chromatograms is the important point here. And if VUV detection can eliminate all operator interpretation, it starts looking like a routine industry solution – and that means very specific and guided applications that give simple information: is the sample a green light or red light? In the petrochemical industry, I can imagine this is possible. In food analysis, the task is more complex.

How about R&D in industry?

In an R&D environment in industry (and academia for that matter), you may not know what you are looking for. Here, every bit of orthogonal information you can get is very helpful. The most powerful identification tool we have right now is the combination of retention indices and mass spectra – if we add to that VUV spectra, it increases the certainty of identification. VUV spectroscopy adds a dimension that is complementary to mass spectrometry, offering selectivity that is difficult to otherwise obtain, particularly for compounds with aromatic rings, for example. In food analysis, volatile compound analysis and the formation of unknown off-flavors springs to mind as an interesting application of VUV spectroscopy. Off-flavors are never normal alkanes, they’re always molecules with very specific chemical groups. And specific chemical groups are what you can see very nicely in the VUV spectrum.