Technical note: Interferences of volatile organic compounds (VOCs) on methane concentration measurements

Lukas Kohl, Markku Koskinen, Kaisa Rissanen, Iikka Haikarainen, Tatu Hannu Polvinen, Heidi Hellén, Mari Pihlatie

Research output: Contribution to journalArticleScientificpeer-review

Abstract

Studies that quantify plant methane (CH4) emission rely on the accurate measurement of small changes in the mixing ratio of CH4 that coincide with much larger changes in the mixing ratio of volatile organic compounds (VOCs). Here, we assessed whether 11 commonly occurring VOCs (e.g. methanol, α- and β-pinene, Δ3-carene) interfered with the quantitation of CH4 by five laser-absorption spectroscopy and Fourier-transformed infrared spectroscopy (FTIR) based CH4 analysers, and quantified the interference of seven compounds on three instruments. Our results showed minimal interference with laser-based analysers and underlined the importance of identifying and compensating for interferences with FTIR instruments. When VOCs were not included in the spectral library, they exerted a strong bias on FTIR-based instruments (64–1800 ppbv apparent CH4 ppmv−1 VOC). Minor (0.7–126 ppbv ppmv−1) interference with FTIR-based measurements were also detected when the spectrum of the interfering VOC was included in the library. In contrast, we detected only minor (<20 ppbv ppmv−1) and transient (< 1 min) VOC interferences on laser-absorption spectroscopy-based analysers. Overall, our results demonstrate that VOC interferences have only minor effects on CH4 flux measurements in soil chambers, but may severely impact stem and shoot flux measurements. Laser-absorption-based instruments are better suited for quantifying CH4 fluxes from plant leaves and stems than FTIR-based instruments; however, significant interferences in shoot chamber measurements could not be excluded for any of the tested instruments. Our results furthermore showed that FTIR can precisely quantify VOC mixing ratios and could therefore provide a method complementary to proton-transfer-reaction mass spectrometry (PTR-MS).
Original languageEnglish
JournalBiogeosciences
Volume16
Issue number17
Pages (from-to)3319-3332
Number of pages14
ISSN1726-4170
DOIs
Publication statusPublished - 4 Sep 2019
MoE publication typeA1 Journal article-refereed

Fields of Science

  • 219 Environmental biotechnology
  • 1172 Environmental sciences
  • NITROUS-OXIDE EMISSIONS
  • SCOTS PINE
  • MONOTERPENE EMISSIONS
  • FOREST
  • CARBON
  • DEPENDENCE
  • PATTERNS
  • LIGHT
  • CH4

Cite this

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title = "Technical note: Interferences of volatile organic compounds (VOCs) on methane concentration measurements",
abstract = "Studies that quantify plant methane (CH4) emission rely on the accurate measurement of small changes in the mixing ratio of CH4 that coincide with much larger changes in the mixing ratio of volatile organic compounds (VOCs). Here, we assessed whether 11 commonly occurring VOCs (e.g. methanol, α- and β-pinene, Δ3-carene) interfered with the quantitation of CH4 by five laser-absorption spectroscopy and Fourier-transformed infrared spectroscopy (FTIR) based CH4 analysers, and quantified the interference of seven compounds on three instruments. Our results showed minimal interference with laser-based analysers and underlined the importance of identifying and compensating for interferences with FTIR instruments. When VOCs were not included in the spectral library, they exerted a strong bias on FTIR-based instruments (64–1800 ppbv apparent CH4 ppmv−1 VOC). Minor (0.7–126 ppbv ppmv−1) interference with FTIR-based measurements were also detected when the spectrum of the interfering VOC was included in the library. In contrast, we detected only minor (<20 ppbv ppmv−1) and transient (< 1 min) VOC interferences on laser-absorption spectroscopy-based analysers. Overall, our results demonstrate that VOC interferences have only minor effects on CH4 flux measurements in soil chambers, but may severely impact stem and shoot flux measurements. Laser-absorption-based instruments are better suited for quantifying CH4 fluxes from plant leaves and stems than FTIR-based instruments; however, significant interferences in shoot chamber measurements could not be excluded for any of the tested instruments. Our results furthermore showed that FTIR can precisely quantify VOC mixing ratios and could therefore provide a method complementary to proton-transfer-reaction mass spectrometry (PTR-MS).",
keywords = "219 Environmental biotechnology, 1172 Environmental sciences, NITROUS-OXIDE EMISSIONS, SCOTS PINE, MONOTERPENE EMISSIONS, FOREST, CARBON, DEPENDENCE, PATTERNS, LIGHT, CH4",
author = "Lukas Kohl and Markku Koskinen and Kaisa Rissanen and Iikka Haikarainen and Polvinen, {Tatu Hannu} and Heidi Hell{\'e}n and Mari Pihlatie",
year = "2019",
month = "9",
day = "4",
doi = "10.5194/bg-16-3319-2019",
language = "English",
volume = "16",
pages = "3319--3332",
journal = "Biogeosciences",
issn = "1726-4170",
publisher = "COPERNICUS GESELLSCHAFT MBH",
number = "17",

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Technical note: Interferences of volatile organic compounds (VOCs) on methane concentration measurements. / Kohl, Lukas; Koskinen, Markku; Rissanen, Kaisa; Haikarainen, Iikka; Polvinen, Tatu Hannu; Hellén, Heidi; Pihlatie, Mari.

In: Biogeosciences, Vol. 16, No. 17, 04.09.2019, p. 3319-3332.

Research output: Contribution to journalArticleScientificpeer-review

TY - JOUR

T1 - Technical note: Interferences of volatile organic compounds (VOCs) on methane concentration measurements

AU - Kohl, Lukas

AU - Koskinen, Markku

AU - Rissanen, Kaisa

AU - Haikarainen, Iikka

AU - Polvinen, Tatu Hannu

AU - Hellén, Heidi

AU - Pihlatie, Mari

PY - 2019/9/4

Y1 - 2019/9/4

N2 - Studies that quantify plant methane (CH4) emission rely on the accurate measurement of small changes in the mixing ratio of CH4 that coincide with much larger changes in the mixing ratio of volatile organic compounds (VOCs). Here, we assessed whether 11 commonly occurring VOCs (e.g. methanol, α- and β-pinene, Δ3-carene) interfered with the quantitation of CH4 by five laser-absorption spectroscopy and Fourier-transformed infrared spectroscopy (FTIR) based CH4 analysers, and quantified the interference of seven compounds on three instruments. Our results showed minimal interference with laser-based analysers and underlined the importance of identifying and compensating for interferences with FTIR instruments. When VOCs were not included in the spectral library, they exerted a strong bias on FTIR-based instruments (64–1800 ppbv apparent CH4 ppmv−1 VOC). Minor (0.7–126 ppbv ppmv−1) interference with FTIR-based measurements were also detected when the spectrum of the interfering VOC was included in the library. In contrast, we detected only minor (<20 ppbv ppmv−1) and transient (< 1 min) VOC interferences on laser-absorption spectroscopy-based analysers. Overall, our results demonstrate that VOC interferences have only minor effects on CH4 flux measurements in soil chambers, but may severely impact stem and shoot flux measurements. Laser-absorption-based instruments are better suited for quantifying CH4 fluxes from plant leaves and stems than FTIR-based instruments; however, significant interferences in shoot chamber measurements could not be excluded for any of the tested instruments. Our results furthermore showed that FTIR can precisely quantify VOC mixing ratios and could therefore provide a method complementary to proton-transfer-reaction mass spectrometry (PTR-MS).

AB - Studies that quantify plant methane (CH4) emission rely on the accurate measurement of small changes in the mixing ratio of CH4 that coincide with much larger changes in the mixing ratio of volatile organic compounds (VOCs). Here, we assessed whether 11 commonly occurring VOCs (e.g. methanol, α- and β-pinene, Δ3-carene) interfered with the quantitation of CH4 by five laser-absorption spectroscopy and Fourier-transformed infrared spectroscopy (FTIR) based CH4 analysers, and quantified the interference of seven compounds on three instruments. Our results showed minimal interference with laser-based analysers and underlined the importance of identifying and compensating for interferences with FTIR instruments. When VOCs were not included in the spectral library, they exerted a strong bias on FTIR-based instruments (64–1800 ppbv apparent CH4 ppmv−1 VOC). Minor (0.7–126 ppbv ppmv−1) interference with FTIR-based measurements were also detected when the spectrum of the interfering VOC was included in the library. In contrast, we detected only minor (<20 ppbv ppmv−1) and transient (< 1 min) VOC interferences on laser-absorption spectroscopy-based analysers. Overall, our results demonstrate that VOC interferences have only minor effects on CH4 flux measurements in soil chambers, but may severely impact stem and shoot flux measurements. Laser-absorption-based instruments are better suited for quantifying CH4 fluxes from plant leaves and stems than FTIR-based instruments; however, significant interferences in shoot chamber measurements could not be excluded for any of the tested instruments. Our results furthermore showed that FTIR can precisely quantify VOC mixing ratios and could therefore provide a method complementary to proton-transfer-reaction mass spectrometry (PTR-MS).

KW - 219 Environmental biotechnology

KW - 1172 Environmental sciences

KW - NITROUS-OXIDE EMISSIONS

KW - SCOTS PINE

KW - MONOTERPENE EMISSIONS

KW - FOREST

KW - CARBON

KW - DEPENDENCE

KW - PATTERNS

KW - LIGHT

KW - CH4

U2 - 10.5194/bg-16-3319-2019

DO - 10.5194/bg-16-3319-2019

M3 - Article

VL - 16

SP - 3319

EP - 3332

JO - Biogeosciences

JF - Biogeosciences

SN - 1726-4170

IS - 17

ER -