Greening the Analytical Lab – 10 Years On

Ten years ago, for the first edition of The Analytical Scientist, I wrote an “In My View” on “greening the analytical lab.” I focused on supercritical fluid chromatography (SFC) – and pointed to the inherent green features of the technique, such as using lower quantities and less toxic solvents than liquid-phase chromatographic methods. I also acknowledged that it shouldn’t be taken for granted – much depends on the way we practice it, as well as the efforts of instrument manufacturers to make the instruments more efficient – especially in reducing solvent consumption.

Unfortunately, where SFC is concerned, my impression is that we haven’t made much progress in terms of “greenness” over the past decade. SFC users often talk about the greenness of the technique without bothering to compare the features of their method to other existing ones. Also, because we believe it to be “good enough,” we don’t investigate green co-solvents (e.g., ethanol), or a less retentive stationary phase to further reduce solvent consumption. It’s not all the chromatographer’s fault though – current instruments still make it difficult to use columns with smaller internal diameter, which would favor the use of lower flow rates.

Nevertheless, if we consider analytical laboratories in general, we have seen considerable progress towards greener techniques in the same 10 years. For example, solvent economy has improved through the adoption of miniaturized techniques and more efficient processes, as well as green solvents, which are now widespread – especially in the field of extraction.

Still, there is room for improvement. For instance, in liquid-phase chromatographic techniques, methanol and acetonitrile are still the most widely used solvents, although they are not the most desirable – in terms of toxicity, for example. Naturally, this is related to their other, more desirable features, such as excellent miscibility to water, low viscosity, and low UV absorbance. Are there other alternatives? The answer is probably yes, but habits are hard to break.

Additionally, we should consider the need to improve the lifetime of some consumables (for example, chromatographic columns), the need to re-use or recycle consumables, and the need to improve recycling of solvents. Right now, recycling is essentially non-existent, so all solvents and plastic devices (for example, pipette tips) are simply burnt after use. A whole chain of after-use processes would be required to make better use of our lab trash – but it would also demand that analysts do a better job of sorting waste.

When it comes to energy efficiency, I’m afraid we’re in a similar situation to SFC; very little progress has been made in the past decade. Today, this question is more pressing than ever; the recent spike in energy costs has forced many laboratories to close or switch off instruments for one or several weeks over the winter to save on energy costs. With future energy costs uncertain, we must find new ways to improve our energy efficiency without sacrificing analytical quality – which certainly has improved significantly over the past decade thanks to the development of automated procedures that reduce human-induced variance.

We could all play our part in one aspect of instrumental energy consumption – switching instruments off when they are not in use. Admittedly, for some instruments, like mass spectrometers, switching the instrument on and off can be problematic to its function and longevity. But other instruments, such as chromatographic systems, can be easily turned off at the end of a sequence run – especially when several hours separate the experiments. But how many of us actually do that? Often sequences are started before leaving the lab for the weekend and cannot be stopped without an operator coming in over the weekend to push the button. It may seem like a small economy, but many of the modules within a chromatographic instrument use about as much energy idly switched on as when they are operating, running experiments. I’m afraid that at least some of the reason for our lack of sustainability here is that we are a little lazy and not very patient… 

Finally, as I pointed out 10 years ago, environmental concerns over solvent economy and energy saving are often not aligned with economic considerations. But given the trends in the energy economy, the two are increasingly aligned. We need – as we did back in 2013 – a concerted effort on the part of analysts to change the way they work while instrument manufacturers need to focus on developing greener solutions.

There’s certainly a greater sense of urgency today, so I hope we will look back in another 10 years and marvel at the progress we’ve made!