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NILU ready to detect new and “unknown” chemicals
The Orbitrap spectrometreOur search for new environmental compounds never stops. However, with NILU’s new mass spectrometer, able to identify chemicals at extremely low levels, the job just got easier.

Environmental chemistry is, and has always been, an important research field at NILU. We search for new environmental compounds in a broad selection of samples including air, sludge, sediment, water, and organisms. Our scientists have a comprehensive and highly developed range of instruments at hand, both at the main office at Kjeller and at our office in the Fram Centre in Tromsø.

However, as from the end of 2016, our hunting for new environmental compounds has taken a big leap. NILU in Tromsø are now the proud owners of an Orbitrap gas chromatography mass spectrometer, the first of its kind in Scandinavia!

Identifying unknown chemicals

Nicholas WarnerScientist Nicholas Warner, NILU
Foto: Christine Solbakken, NILU

"This gives NILU a powerful tool to identify new emerging chemicals and their threats to the environment, especially in the vulnerable Arctic”, says Dr. Nicholas Warner, senior scientist at NILU in Tromsø.

“The high resolution capabilities of this instrument provide us with the ability to identify known and unknown chemicals in complex samples, even at trace levels”, Warner explains. “We now have the ability to identify almost every compound present in a sample with high accuracy, even those which occur in extremely small amounts - eg. 1 picograms (one trillionth of a gram) per gram sample and lower - for some chemicals down to femtogram levels.”

Mass resolution is the ability of an instrument to distinguish between chemicals of different mass – the higher number, the greater the mass separation efficiency.

“With this instrument we can conduct a routine trace chemical analysis, collecting highly resolved full mass spectra, at 60 000 mass resolution. This means that we can separate chemicals that differ by only 0.001 atomic mass units”, Warner explains. “This is extremely powerful when we are trying to identify new chemicals, or what we refer to as "unknown chemicals”. These are chemicals we did not know were there, because we lacked the ability to separate them from other chemicals of similar mass”.

Filling a gap

Dorte HerzkeSenior Scientist Dorte Herzke, NILU
Foto: Christine Solbakken, NILU

Because of this specificity, NILU scientists are now able to achieve much lower detection limits. The ability to select a compound’s mass with such high mass accuracy, means that chemical noise introduced from the sample matrix or other chemicals present can be filtered away more effectively compared to lower mass resolution instruments.

“Considering the fact that NILU already owns a mass spectrometer performing between some hundred up to 10 000 mass resolution, the newly acquired Orbitrap provides an array of new opportunities”, says Warner.

“This type of analysis fills a knowledge gap between the regulatory authorities and research that has existed for many years”, said Dr. Dorte Herzke at NILU in Tromsø. “Now we are finally able to look for potential contaminants in retrospective, since the data file from the analysis provides information that we can retrieve at a later date. This means that there is no need to prepare the sample again. Using the Orbitrap, we also expect to find and identify new environmental compounds, such as persistent organic pollutants (POPs)”, she adds.

How mass spectrometers work

Mass spectrometers measure the masses of isotopes, molecules and molecular fragments by ionizing them, and then sending them through electrical and magnetic fields up to a detector. Low-resolution mass spectrometers can only separate between chemicals that differ by one mass unit (i.e., 255 vs. 256). With a high-resolution mass spectrometer such as the one NILU now has acquired, the separation potential is much higher. It is able to separate chemicals with much smaller differences in mass, i.e., 255.27602 vs. 255.27150.


Read also:

Non-target screening – The complete inventory (NILU annual report 2012)

Non-target screening – A powerful tool for selecting environmental pollutants: http://www.miljodirektoratet.no/Documents/publikasjoner/M27/M27.pdf

Contact:

Nicholas Warner nw@nilu.no
Dorte Herzke dhe@nilu.no

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