Using scientific instruments to come to grips with pollution

The assault by pollutants can seem relentless. Carbon dioxide in the air is leading to climate catastrophe, and fluorinated compounds in the water threaten to harm us. A small consolation is that scientists, aided by scientific instrument makers, are studying these pollutants with increasing precision.

That was a takeaway from the Analytica instrumentation exhibition and conference held in Munich in April, where analysis of pollutants in the environment was a focus of both scientists giving talks and companies presenting their wares.

Air pollution “is a big problem,” said Ralf Zimmermann, professor of chemistry at the University of Rostock in Germany, during a symposium at the event. “It is causing approximately 7 million premature deaths per year,” he said, citing research published by the World Health Organization.

To understand how pollution is created, it helps to measure pollutants in real time, and for this, sometimes you need a laboratory in the air, said Nicholas Marsden, a research fellow at the University of Manchester and a researcher at the UK’s National Centre for Atmospheric Science. Marsden is part of a team collecting live data in the atmosphere from a converted BAE-146-301 plane.

Marsden and his team have replaced the aircraft’s passenger seats with “lots and lots of instruments,” including a variety of mass spectrometers, he said. Probes and inlets allow air to be sampled as the plane flies at speeds of about 100 m/s. “We’ve got to make these measurements with high resolution because in a few seconds we’ve left the scene. We don’t do sample collection. This is not possible. The situation is too dynamic,” Marsden said.

Primary emissions in the atmosphere such as gases, particulates, and aerosols interact with one another in secondary processes that can result in aerosol modification. Marsden combines data from the airborne lab with data from an atmospheric simulation chamber to determine the fate of certain emissions. “There’s a hugely complex picture that represents a huge analytical challenge,” he said.

In one of his projects, Marsden has been analyzing the evolution of emissions plumes from ships in the English Channel. “The only way to look at the plume evolution is to go out there and fly through the plume and look at how it evolves in time. Here we are chasing down the ship and flying into the plume, which is quite turbulent, which is why I dropped my tea,” Marsden said during a presentation at Analytica as he described a photograph of himself aboard the BAE-146-301.

This is not how Olli Sippula studies pollution in the atmosphere. Instead of heading into the skies, the University of Eastern Finland scientist simulates how emissions from ships and aircraft transform the atmosphere by running similar engines and fuels in labs firmly rooted on the ground.

One of Sippula’s recent findings is that photochemical aging of jet engine exhaust leads to secondary organic aerosol formation—and an increase of particulate mass by a factor of about 300. His conclusion in a talk on the subject was that emission regulations “are not very strict.”

A challenge for scientists in the field is determining how the complex interactions of chemical mixtures in the atmosphere fit into models for predicting climate impacts, said Nicole Riemer, a professor specializing in the computer simulation of atmospheric aerosols at the University of Illinois Urbana-Champaign, in a presentation at Analytica. Findings from the Intergovernmental Panel on Climate Change show that microscale chemical processes have an impact on climate, but no single instrument can characterize all aspects of aerosol mixing, Riemer said. “We struggle with this multiscale problem.”

Connecting molecular-level interactions with climate change continues to be problematic. But scientists studying carbon dioxide in the atmosphere are being helped by advances in instrumentation.

Saturated-absorption cavity ring-down (SCAR) spectroscopy is emerging as “a reliable option for highly accurate analysis” of CO₂ in the atmosphere, Paolo De Natale, an expert in atomic and molecular high-precision spectroscopy and professor at Italy’s National Institute of Optics, said in a presentation. A SCAR spectrometer can pick out the carbon isotope emitted during the burning of fossil fuels—distinct from the ¹⁴C isotope derived from biological sources—at concentrations of parts per quadrillion, De Natale said. This makes SCAR spectroscopy “good for assessing global warming” and enables scientists to monitor the climate in real time, he said, predicting that deployment of SCAR instrumentation worldwide could be in the cards.

Indeed, at Analytica, the small Italian firm NC Technologies was showing what it claims is the first commercial SCAR spectrometer for CO₂ analysis, along with a portable sampling machine named the 8070 Air CO₂. “Atmospheric monitoring is a bit challenging now” because institutions want to differentiate between the CO₂ that is from fossil fuels and CO₂ that is natural, said Christian Frigerio, an R&D specialist at NC. “We are trying to keep up with their needs.”

Using the company’s new instruments, scientists can take a sample in 10 min and analyze it in about 30 min, Frigerio said. Today, instruments for analyzing CO₂ levels are supplied mainly by major companies, but their sample analysis takes hours or even weeks, Frigerio claimed. NC’s approach is faster, thanks to a novel sample-cleaning step that uses undisclosed reagents to remove from the samples N₂O and other compounds that could otherwise interfere with analysis, he said.

NC is hoping its 8070 Air CO₂ and SCAR spectrometer will be taken up by the Integrated Carbon Observation System, an organization that runs 46 stations around the world for measuring greenhouse gas concentrations. The 8070 Air CO₂ can be used for continuous analysis on-site or to take “samples of air wherever you are—let’s say from Mount Everest to the sea. It could even be loaded onto a plane,” Frigerio said.

Meanwhile, there is growing interest in the use of Fourier-transform infrared (FTIR) spectrometers for analyzing captured CO₂ destined for underground storage, said Sami Ketonen, field product manager for Gasmet Technologies, a firm based in Finland. Until recently, Gasmet’s FTIR instruments were used mainly to assess gases emitted by industrial plants. FTIR spectroscopy is not as accurate as SCAR spectroscopy, but analysis is relatively rapid. At Analytica, Gasmet was showing off its latest FTIR model—a portable instrument the size of a microwave oven.

Major instrument makers at Analytica said they are also focused on developing instruments that are faster and more accurate at analyzing other pollutants, especially per- and polyfluoroalkyl substances (PFAS).

Although the overall amount of PFAS from industry is declining, a relatively new environmental threat from PFAS is occurring in the form of the metabolites of fluorinated pharmaceuticals, said Jan Koschorreck, a scientist for the Umweltbundesamt, the German government’s environment agency, in a presentation at Analytica. Just one fluorinated diabetes medicine is consumed at a scale of 60 metric tons each year in Germany, he said.

The response of regulators to such threats has been slow. “It takes 22 years to regulate a compound in Europe,” Koschorreck said. Nevertheless, the innovative power of the environmental analysis community is a great support for environmental policy and research, he said.

Agilent Technologies, one of the biggest makers of lab equipment, provides a full suite of analytical instruments including liquid chromatography and mass spectrometry (LC-MS) devices suited to the analysis of PFAS, said Sudharshana Seshadri, the firm’s general manager for LC, MS, and automation. Agilent is focused on meeting the growing needs of chemists analyzing PFAS, and it even sells PFAS-free consumables such as piping for its instruments, Seshadri said.

“PFAS is being regulated more and more, and testing requirements are going to broaden out from drinking water and wastewater to food and air,” she said. The analytical characterization of these pollutants “are some of the gnarliest problems that are out there.”

PerkinElmer, another major scientific instrument firm, said it is stepping up its offering of hardware for analyzing pollutants. “We have a very tight focus on being a good partner for regulatory agencies participating in the development of environmental regulations,” said John Luck, the company’s then chief operating officer, who has since left the company.

PerkinElmer has helped regulators in France and the US develop methods for assessing PFAS pollution, and regulators in China, Europe, and the US with air pollution detection methods. The company now has more than 250 application scientists devoted to such activities worldwide, Luck said.

Scientists at Analytica were seeking out an ever greater array of instruments and research methods in their quest to answer fundamental questions about pollution in the environment. It was also clear that the scientific instrument industry wants to better serve this field. As Luck said, “If we see that it is crucial to the community, it is part of our obligation as a good steward to participate where we can in this. I often find that the profitability then follows.”