Are we Greenwashing Analytical Chemistry?

What?  

I have no idea?

Maybe, because it’s a buzzword these days, right?

I don’t know enough about the green never mind the wash.  

Nah, it’s just what the focus is these days.

5 responses from colleagues and friends when I recently put this question to them.

I guess the range of response reflects my own knowledge and opinion, until very recently, when I started to think more the subject.

I’ve held some opinions up to this point. The fact that companies surely have more impactful sustainability targets than the relatively minor contribution from their analytical department.  That really, I’m too busy to properly think about sustainability in a meaningful way.  That sustainability appears to be getting more airtime and there are one or two companies who seem to be taking a lead and others who seem to be milking it a little.

If this paints a dim picture, well at least you know I’m honest.

Perhaps my redemption is that recently, I have started to become much more interested in the greening of analytical chemistry.  Why, I cannot say.  There was, to my knowledge, no catalytic event, no road to Damascus experience.  Maybe just a point where I had enough time to do a little background research and begin to apply some further thinking to reduce our environmental impact and play our part in the global green initiative.

There can be few people on our planet who are unaware of the importance of reducing waste, cutting energy consumption, and lowering carbon footprint.  I’m more than aware of the effect we have on our plant and it’s climate, and dutifully reduce, reuse and recycle wherever possible in my personal life.  

So, what do I need to know to be a good global and corporate citizen in the laboratory?

I started with the 12 Principles of Green Chemistry, developed by Paul Anastas and John Warner in 1998 [1].  Which made me feel bad.  Surely I haven’t taken 25 years to wake up and smell the organic, sustainably produced coffee?

1. Waste Prevention – prevent waste rather than being smart about dealing with it
2. Atom Economy – reduce waste at a molecular level by ensuring atoms from reagents are included in the final chemical product
3. Less Hazardous synthesis – chemical reactions and synthesis designed to be as safe as possible
4. Designing Safe Chemicals – minimize toxicity and environmental fate by molecular design
5. Safe solvents and auxiliaries – choose the safest solvents available and use the least amount of solvent and other reagents
6. Design for energy efficiency – choose the least energy intensive chemical route
7. Use renewable feedstocks – use chemicals made from renewable (organic) rather than petrochemical sources
8. Reduce derivatives – minimise the use of temporary derivatives such as protecting groups, to reduce reaction steps, required resource and waste creation
9. Catalysis – use catalytic rather than stoichiometric reagents
10. Design for degradation – design for chemicals that degrade and can be more easily discarded without bioaccumulation or environmental persistence
11. Real time pollution prevention – monitor reactions in real time to prevent the formation or release of polluting substances
12. Safer chemistry for accident prevention – develop chemical reactions which are inherently less hazardous and minimize risk

My reaction was that there was one or two ‘interesting’ thoughts here.  I can get on board with waste reduction, use of safer solvents, energy efficiency and real time monitoring, because that sounds like analytical chemistry. However, generally this felt like a manifesto for synthetic organic chemists.  Nothing wrong with that, but I’m a different type of chemist, with different considerations. I really hope I’m bringing you along on this forthright thought process and you haven’t disowned me at this point.

I need something more tangible to really spark my thought processes on analytical sustainability.

Next comes the 12 principles of Green Analytical Chemistry (GAC) by Agnieszka Gałuszka et.al.  in 2013 [2].  This seems a lot more promising and relevant;

1. Direct Analytical Techniques Should Be Applied to Avoid Sample Treatment.
2. Minimal Sample Size and Minimal Number of Samples Are Goals.
3. In Situ Measurements Should Be Performed.
4. Integration of Analytical Processes and Operations Saves Energy and Reduces the Use of Reagents
5. Automated and Miniaturized Methods Should Be Selected.
6. Derivatization Should Be Avoided
7. Generation of a Large Volume of Analytical Waste Should Be Avoided and Proper Management of Analytical Waste Should Be Provided.
8. Multianalyte or Multiparameter Methods Are Preferred versus Methods Using One Analyte at a Time.
9. The Use of Energy Should Be Minimized.
10. Reagents Obtained from Renewable Source Should Be Preferred.
11. Toxic Reagents Should Be Eliminated or Replaced
12. The Safety of the Operator Should Be Increased.

Ok, so now you really have my attention.  

I’m into Automation and Integration of processes.  I like saving energy and reducing waste because it saves me cost, I don’t like derivatisation because the reactions are clumsy and the reagents, generally have to be handled in fume cupboard and I like multivariate analysis because I understand it and one factor at a time (OFATO) method development  approaches waste time and are, frankly, less interesting.  I also like analyses which can cover all relevant analytes in a single method.  Whilst a detailed treatment of each of the principles is outside the scope of this article, an excellent discussion can be found in references 2 and 4.After further consideration of the GAC principles, I began to think that maybe, even though unconsciously, I’d been following a few a few of these principles and steering a greener course over recent years.

We all know that column geometry has been reducing over time.  150 x 4.6mm were the norm. at the turn of the century and now, anecdotally, I’d say that 100 x 2.1mm is the new normal.   This has been facilitated by the introduction of smaller particle sizes and superficially porous particles.  Of course, reduced column dimension and particle size typically result in lower solvent usage and higher efficiency separations.

Higher efficiency chromatography leads to an increase in the number of analytes which can be separated per injection (peak capacity) and the reduction in column geometry drives lower sample (or at least injection) volumes, both directly in line with the principles of green chemistry.

It's a very long time since I used normal phase chromatography, whose eluent systems are organic solvents, and this is primarily due to the introduction of reversed phase stationary phases with polar functional groups and of Hydrophilic Interaction Chromatography (HILIC), both of which are designed to retain and separate more polar analytes.  It’s also very unusual to use THF in reversed phase eluent systems and the use of primary amines as eluent modifiers to improve peak shape of basic compounds is no longer required due to improvements in bonded phase silica technology.  Silica which can be used at more extreme pH’s has also led to a reduction in the use of ion-pairing reagents.

This reduction in the use of more toxic solvents and a reduction in the use of additional reagents is directly in line with the principles of green chemistry.

A ‘waste’ feature that I haven’t really considered previously is the use of paper within the laboratory.  I think it’s fair to say that we are doing reasonably well in reducing the use of paper – consider the use of data systems to produce a result in-silico and the use of LIMS and electronic signatures which reduce the requirement to print out methods, data and results for wet ink signatures as part of our quality compliance.  

So, I’m starting to feel a little better about my previously lackadaisical approach to green approaches and have even started using a nice GREEN calculator to characterise the green credentials of each of my analytical methods [3,4].  This is a really nice tool which produces an easy to interpret graphical output indicating the ‘weighted score’ for each of the 12 GAC principles. 

So, what of sample preparation?  

I feel that in order to properly consider the green credentials of an analytical method, we need to take into account any sample preparation operations, which can obviously involve solvents, reagents and energy consumption.  The AGREE tool excludes these aspects via it’s first principle, which is to avoid or exclude sample preparation wherever possible.  Here is where I found the AGREEprep tool and another set of green principles, termed Green Sample Preparation (GSP) [5,6].  Whilst the principles are similar in nature to those of the GAC list, the tool and its accompanying tutorial materials, make it reasonably straightforward to rank various sample preparation techniques and signpost possible improvements in the green credentials of your method.

1. Favour in situ sample preparation
2. Use safer solvents and reagents
3. Target sustainable, reusable, and renewable materials
4. Minimize waste
5. Minimize sample, chemical and material amounts
6. Maximize sample throughput
7. Integrate steps and promote automation
8. Minimize energy consumption
9. Choose the greenest possible post-sample preparation configuration for analysis
10. Ensure safe procedures for the operator

Again, this list appeals as I recognise a number of areas which have been the focus of development activities in our industry over recent years.

The green benefits here are obvious, however we often overlook Principle 10 of the GSP list, that of the reduction of exposure of the operator to harmful chemicals.  Most automated sample preparation systems are fully contained, leading to good compliance with Principle 10.

By combining the approaches of GSP and GAC we can get a good relative measure of the ‘green-ness’ of our analytical workflow. Other similar, analytical chemistry relevant measurement tools and methods, that I’ve found whilst researching this topic include;

• AMGS Calculator (ACS Green Chemistry Institute) [7]
• Analytical Eco-Scale for assessing the greenness of analytical procedures [8]
• Complementary green analytical procedure index (ComplexGAPI) and software [9, 10]

I‘ve not looked into these other tools in details so won’t comment at this point on their relative merits versus the AGREE tools that I’ve discussed above.

So, given that we have these great tools available and that, without really noticing it, I’ve been following several of these green principles in recent years, can we now answer the titular question in the negative and proclaim that we are indeed where we need to be with sustainability in analytical chemistry?  Well, I have some doubts.  These may be due to personal ignorance, which I’m sure readers will educate me on, or it could be that we have a way to go yet before we can relax and say that we are truly playing our part in the drive towards better chemical sustainability in the analytical lab.

Firstly, I’m really not sure just how green the chemicals are which I use.  Are there ‘greener’ suppliers? How green are the reagents that I use in sample preparation and in eluent preparation?  Until now, I hadn’t seen a scale or unified approach to ‘scoring’ the green credentials of my solvents and chemicals which makes it possible for me to choose and source solvents and reagents in a more sustainable way.  I’ve recently come across the DOZN ™ [11] measure from MilliporeSigma which does seem to be heading in the right direction and I’ll be making use of this tool going forward.  If other manufacturers have tools or information which make sustainable choices more obvious, then please let me know and I’d be happy to promote them in a future blog.

I’m also still slightly concerned about operator exposure to eluent systems, chemicals and reagents.  We recently moved to install some safer caps and filters for our eluent bottles and a system which reduces exposure risk when disposing eluent waste, but I do feel that I’m a little late to the party here and see plenty of labs which have not taken such steps yet.  

I also believe that automation of sample preparation activities involving larger volumes of solvents could be taken more seriously in terms of reducing operator exposure.  I know I’m behind the curve in this respect and feel that many others may be in the same position.  Exposure of operators also means environmental exposure to potentially damaging chemicals.

Think of the amount of plastic and glass that we use in the laboratory.  Pipette tips, pipette tip racks, plastic Pasteur pipettes, vials, solvent Winchester bottles, gloves, volumetric glassware, plastic solvent dispenser bottles etc. etc.  Do you recycle those in your laboratory? Do you know of a supplier who offers to recycle these in a financially reasonable way?  Should the cost even be a consideration if we are serious about becoming more sustainable?  What about the amount of ‘blue roll’ that is used, and could we source more sustainable laboratory paper-roll?

Many of the calculators that I’ve mentioned above rely on the calculation of energy consumption of various instruments, and in a particular set of power units.  I really struggle to find these figures from the manufacturers and it would be much more helpful if we could standardise on a power consumption unit and the manufacturers provided these figures on purchase or through a readily accessible section of their website.

I could go on.  I’m sure there will be readers who have done more and considered other aspects of sustainability that I haven’t thought about yet and please get in touch if this is the case.  What I can promise the reader who thinks the above discussion is a poor reflection on my own green credentials, is that I have personally committed to undertake more research, implement further sustainability measures and work hard to find suppliers who are more advanced on their sustainability journey.

Are we Greenwashing Analytical chemistry?  

I’ve been greener by accident, by following industry trends which are inherently more sustainable, but I realise that I, and perhaps we all, have a way to go before we can be comfortable.  Let’s say the lid is off the tin of greenwash and we need to guard against complacency or marketing our green credentials before we’ve taken a good long look at what this really means.

References

[1] Anastas, P. T.; Warner, J. C. Green Chemistry: Theory and Practice, Oxford University Press: New York, 1998, p.30

[2] Agnieszka Gałuszka, Zdzisław Migaszewski, Jacek Namieśnik, The 12 principles of green analytical chemistry and the SIGNIFICANCE mnemonic of green analytical practices, TrAC Trends in Analytical Chemistry Volume 50, October 2013, Pages 78-84

[3] Francisco Pena-Pereira, Wojciech Wojnowski, Marek Tobiszewski, AGREE Analytical GREEnness Metric Approach and Software, Anal. Chem. 2020, 92, 10076−10082

[4] https://mostwiedzy.pl/en/wojciech-wojnowski,174235-1/AGREE?

[5] Francisco Pena-Pereira, Marek Tobiszewski, Wojciech Wojnowski,  Elefteria Psillakis, A Tutorial on AGREEprep an Analytical Greenness Metric for Sample Preparation, Advances in Sample Preparation 3 (2022) 100025

[6] https://mostwiedzy.pl/en/wojciech-wojnowski,174235-1/agreeprep

[7] https://www.acsgcipr.org/tools-for-innovation-in-chemistry/about-the-analytical-method-greenness-score-amgs-calculator/

[8] Agnieszka Gałuszka, Zdzisław M Migaszewski, Piotr Konieczka, Jacek Namieśnik, Analytical Eco-Scale for assessing the greenness of analytical procedures, TrAC Trends in Analytical Chemistry 37:61–72

[9] Justyna Płotka-Wasylka and Wojciech Wojnowski, Complementary green analytical procedure index (ComplexGAPI) and software, Green Chem., 2021, 23, 8657-8665 Green Chem., 2021, 23, 8657-8665 

[10] https://mostwiedzy.pl/en/justyna-plotka-wasylka,647762-1/complexgapi 

[11] https://www.sigmaaldrich.com/GB/en/services/software-and-digital-platforms/dozn-tool?utm_source=redirect&utm_medium=promotional&utm_campaign=dozn