Turning the Tide
Nine Power List Planet Protectors discuss the biggest challenges in environmental analysis today and how we overcome them…
| 6 min read | Discussion
Emerging contaminants
Juliane Hollander: One big challenge I work on is deciphering the exposure of the environment and humans with thousands of man-made chemicals. This can only be achieved through a combination of appropriate sampling, sample preparation, separation and sensitive detection techniques together with data mining tools.
Andrew Ault: One of the biggest challenges in environmental analysis is understanding human exposure to a range of emerging and changing pollutants. From my perspective, inhaled pollutants are critical to understand, as our lungs are much less adept at handling novel toxins and pollutants in comparison to exposures to our gut or skin, where the body is more prepared to face unexpected exposures. This is why our bodies are often many times more sensitive to inhalation exposure versus ingestion or dermal exposure. While as analytical chemists we know that the body responds to distinct chemicals differently, our environmental regulations for air pollution exposure are dominated by mass concentrations (e.g., particulate matter less than 2.5 µm, known as PM2.5), irrespective of chemical composition. This means that 10 µg/m3 of sea spray particles from the ocean are considered as harmful as the same concentration straight out of a truck’s tailpipe, which intuitively to an analytical scientist doesn’t make a lot of sense. The reason these regulations are based on mass and not composition is that we currently lack robust and inexpensive measurements of aerosol chemical composition. While we have made strides with expensive instrumentation in the US and Europe, if we want to protect the whole planet and a lot of the global south that has not had the same access to advanced measurement, we need to address this issue. I am optimistic that analytical science can have an incredibly positive impact on human health globally.
Susan Richardson: How to identify the 100s to 1000s of chemicals that are present in our waters. The issue is that they are typically found at low levels (ng/L-ug/L levels) and are complex mixtures, which makes things tricky for LC-MS analysis, which suffers from ion suppression (you could miss the detection of chemicals entirely!). When you have standards, it’s easy… You can develop sensitive methods for them. But, when you are doing true non-target work and you don’t know what to expect and what conditions are optimal to detect them, it’s difficult. Also, I have found that I have more success manually interpreting mass spectra, but hopefully one day, AI/machine learning will improve the ability for software to quickly identify compounds. Right now, it has a long way to go.
Torsten Schmidt: As usual in science, there is not just one challenge ahead – and many of these are not solely limited to environmental analysis.
Take, for example, the use of high-resolution mass spectrometry, which started mainly in -omics but is now being extensively used in environmental analysis. The fusion of information from chemical analysis, effect-based methods and environmental -omics, including the necessary improvements in data processing and analysis, is a major task for the coming years. This will require highly sophisticated and, at best, automated high-throughput instrumentation and computing capabilities.
On the other end of instrumental complexity, further developments in low-cost, in-situ or at least mobile analysers would be extremely helpful for better coverage of environmental data. This could include citizen science approaches with all the necessary precautions to ensure data quality. The integration of today's ubiquitous smartphone devices into environmental monitoring offers significant potential, especially on a large scale, which once again necessitates big data analysis.
Compound-wise, legacy compounds such as the group of perfluorinated alkyl substances (PFAS) will surely keep environmental analysts busy for decades to come. Although many worthy attempts have already been made, the holy grail of a unique sum parameter for all PFAS in complex environmental samples is still not within reach.
In water analysis I still see a (reasonable) shift towards persistent and mobile organic compounds that have also reached registration of chemicals under REACH in Europe. These compounds require a widening of the analytical window towards more polar compounds. In the meantime, there are several complimentary separation methods available that in combination with mass spectrometric detection have substantially expanded our coverage of such compounds, including HILIC, IC, SFC and CE. But none of these methods have yet found their way into standardization and regulation and thus are merely used in research so far. This is an example of a general challenge we face: ensuring a faster transfer of research results into monitoring practice.
Technological hurdles
Diana Aga: There are many big challenges in environmental analysis today. First, we need to have unbiased sample cleanup techniques. In general, there is no “one size fits all” sample preparation procedure. For example, when we perform solid-phase extraction to pre-concentrate samples, the choice of sorbent and the elution solvent typically limits the range of compounds that are adsorbed or eluted, affecting the recoveries of the most hydrophilic and the most hydrophobic analytes. Ideally, we need to have an isotopically labeled surrogate for every single analyte to account for losses, if analysis is being done by chromatography/mass spectrometry. However, labeled surrogates are not always commercially available, or can be very expensive.
Emma Schymanski: I think there are two major challenges (well, I’m sure there are more, but in my immediate area). On the one hand we have the sheer immensity of chemical space, which we still cannot enumerate despite our databases containing hundreds of millions of chemicals. On the other hand it’s our inability as a community to agree on harmonized workflows to establish some standardized methods for non-target screening (NTS) of certain (well characterized) subsets of the chemical space, so we can finally move beyond the current necessity for target analysis before action can be taken. Standardization and harmonization of some established methods will have many advantages, allowing e.g. established protocols and stable data processing workflows rather than custom analysis, which is much easier for routine applications. While it’s important to allow more freedom in research for novel questions, standardization and harmonization is critical for reproducibility, comparability and high throughput. In many cases the discrepancies are small and there is ample evidence to standardize and harmonize (and document the caveats). This will help to identify the gaps for which standard workflows are not sufficient, where additional approaches may still be needed. Despite our many community efforts over the years, we still seem a way off from this point, but I hope we will reach it soon. Hopefully we will have gathered enough data (see other answers) to act on this point soon!
Janusz Pawliszyn: Sustainable technologies. Develop validated screening methods and technologies compatible with on-site deployment.
