Review of Hellén et al. 2016: Using in situ CG-MS for analysis of C2-C7 volatile organic acids in ambient air of a boreal forest site

Abstract. An in situ method for studying gas-phase C2–C7 monocarboxylic volatile organic acids (VOAs) in ambient air was developed and evaluated. Samples were collected directly into the cold trap of the thermal desorption unit (TD) and analysed in situ using a gas chromatograph (GC) coupled to a mass spectrometer (MS). A polyethylene glycol column was used for separating the acids. The method was validated in the laboratory and tested on the ambient air of a boreal forest in June 2015. Recoveries of VOAs from fluorinated ethylene propylene (FEP) and heated stainless steel inlets ranged from 83 to 123 %. Different VOAs were fully desorbed from the cold trap and well separated in the chromatograms. Detection limits varied between 1 and 130 pptv and total uncertainty of the method at mean ambient mixing ratios was between 16 and 76 %. All straight chain VOAs except heptanoic acid in the ambient air measurements were found with mixing ratios above the detection limits. The highest mixing ratios were found for acetic acid and the highest relative variations for hexanoic acid. In addition, mixing ratios of acetic and propanoic acids measured by the novel GC-MS method were compared with proton-mass-transfer time-of-flight mass spectrometer (PTR-TOFMS) data. Both instruments showed similar variations, but differences in the mixing ratio levels were significant.

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Using in situ GC-MS for analysis of C2-C7 volatile organic acids in ambient air of a boreal forest site

10.5194/amt-2016-223 ◽

2016 ◽

Author(s):

Heidi Hellén ◽

Simon Schallhart ◽

Arnaud P. Praplan ◽

Tuukka Petäjä ◽

Hannele Hakola

Keyword(s):

Organic Acids ◽

Boreal Forest ◽

Mass Spectrometer ◽

Detection Limits ◽

Ambient Air ◽

Cold Trap ◽

Mixing Ratios ◽

Volatile Organic ◽

Volatile Organic Acids

Abstract. Abstract. An in situ method for studying C2-C7 monocarboxylic volatile organic acids (VOAs) in ambient air was developed and evaluated. Samples were collected directly into the cold trap of the thermal desorption unit (TD) and analysed in situ using a gas chromatograph (GC) coupled to a mass spectrometer (MS). A polyethylene glycol column was used for separating the acids. The method was validated in the laboratory and tested on the ambient air of a boreal forest in June 2015. Recoveries of VOAs from fluorinated ethylene propylene (FEP) and heated stainless steel inlets were acceptable. Different VOAs were fully desorbed from the cold trap and well separated in the chromatograms. Detection limits varied between 1 and 130 pptv and total uncertainty of the method at mean ambient mixing ratios ranged between 16–76 %. All straight chain VOAs except heptanoic acid in the ambient air measurement were found with mixing ratios above the detection limits. The highest mixing ratios were found for acetic acid and the highest relative variations for hexanoic acid. In addition, mixing ratios of acetic and propanoic acids measured by the novel GC-MS method were compared with proton-mass-transfer time-of-flight mass spectrometer (PTR-TOFMS) data. Both instruments showed similar variations, but differences in the mixing ratio levels were significant.

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Sesquiterpenes identified as key species for atmospheric chemistry in boreal forest by terpenoid and OVOC measurements

10.5194/acp-2018-399 ◽

2018 ◽

Cited By ~ 1

Author(s):

Heidi Hellén ◽

Arnaud P. Praplan ◽

Toni Tykkä ◽

Ilona Ylivinkka ◽

Ville Vakkari ◽

...

Keyword(s):

Organic Acids ◽

Boreal Forest ◽

Atmospheric Chemistry ◽

Vertical Mixing ◽

Diurnal Variations ◽

Oxidation Products ◽

Key Species ◽

Seasonal And Diurnal Variations ◽

Volatile Organic ◽

Volatile Organic Acids

Abstract. Concentrations of terpenoids (isoprene, monoterpenes, sesquiterpenes) and oxygenated volatile organic compounds (OVOCs, i.e. aldehydes, alcohols, acetates and volatile organic acids) were investigated during two years at a boreal forest site in Hyytiälä, Finland, using in situ gas chromatograph-mass spectrometers (GC-MS). Seasonal and diurnal variations of terpenoid and OVOC concentrations as well as their relationship with meteorological factors were studied. Of the studied VOCs, C2-C7 unbranched volatile organic acids (VOAs) were found to have the highest concentrations mainly due to their low reactivity. Of the terpenoids, monoterpenes (MTs) had highest concentrations at the site, but also 7 different highly reactive sesquiterpenes (SQTs) were detected. Monthly and daily mean concentrations of most terpenoids, aldehydes and VOAs were found to be highly dependent on the temperature. Highest exponential correlation with temperature was found for a SQT (β-caryophyllene) in summer. The diurnal variations of the concentrations could be explained by sources, sinks and vertical mixing. Especially the diurnal variations of MT concentrations were strongly affected by vertical mixing. Based on the temperature correlations and mixing layer height simple proxies were developed for estimating MT and SQT concentrations. To estimate the importance of different compound groups and compounds for the local atmospheric chemistry, reactivity with main oxidants (OH, NO3 and O3) and production rates of oxidation products (OxPR) were calculated. MTs dominated OH and NO3 radical chemistry, but SQTs had a major impact on ozone chemistry, even though concentrations of SQT were 30 times lower than MT concentrations. SQTs were the most important also for the production of oxidation products. Since SQTs have high secondary organic aerosol (SOA) yields, results clearly indicate the importance of SQTs for local SOA production.

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THE NON-VOLATILE ORGANIC ACIDS OF GREEN TOBACCO LEAVES

Journal of Biological Chemistry ◽

10.1016/s0021-9258(18)76626-x ◽

1931 ◽

Vol 90 (3) ◽

pp. 637-653

Author(s):

Hubert Bradford Vickery ◽

George W. Pucher

Keyword(s):

Organic Acids ◽

Tobacco Leaves ◽

Volatile Organic ◽

Volatile Organic Acids

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Volatile organic acids produced during kerogen maturation— amounts, composition and role in migration of oil

Organic Geochemistry ◽

10.1016/0146-6380(88)90067-8 ◽

1988 ◽

Vol 13 (1-3) ◽

pp. 461-465 ◽

Cited By ~ 42

Author(s):

Tania Barth ◽

Anne Eva Borgund ◽

Anne Lise Hopland ◽

Arne Graue

Keyword(s):

Organic Acids ◽

Volatile Organic ◽

Volatile Organic Acids

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Ambient measurements of aromatic and oxidized VOCs by PTR-MS and GC-MS: intercomparison between four instruments in a boreal forest in Finland

Atmospheric Measurement Techniques ◽

10.5194/amt-8-4453-2015 ◽

2015 ◽

Vol 8 (10) ◽

pp. 4453-4473 ◽

Cited By ~ 10

Author(s):

M. K. Kajos ◽

P. Rantala ◽

M. Hill ◽

H. Hellén ◽

J. Aalto ◽

...

Keyword(s):

Mass Spectrometry ◽

Boreal Forest ◽

Proton Transfer Reaction ◽

Systematic Difference ◽

Gas Chromatography Mass Spectrometry ◽

Forest Site ◽

Mixing Ratios ◽

Measurement Protocol ◽

R Value

Abstract. Proton transfer reaction mass spectrometry (PTR-MS) and gas chromatography mass spectrometry GC-MS) are commonly used methods for automated in situ measurements of various volatile organic compounds (VOCs) in the atmosphere. In order to investigate the reliability of such measurements, we operated four automated analyzers using their normal field measurement protocol side by side at a boreal forest site. We measured methanol, acetaldehyde, acetone, benzene and toluene by two PTR-MS and two GC-MS instruments. The measurements were conducted in southern Finland between 13 April and 14 May 2012. This paper presents correlations and biases between the concentrations measured using the four instruments. A very good correlation was found for benzene and acetone measurements between all instruments (the mean R value was 0.88 for both compounds), while for acetaldehyde and toluene the correlation was weaker (with a mean R value of 0.50 and 0.62, respectively). For some compounds, notably for methanol, there were considerable systematic differences in the mixing ratios measured by the different instruments, despite the very good correlation between the instruments (mean R = 0.90). The systematic difference manifests as a difference in the linear regression slope between measurements conducted between instruments, rather than as an offset. This mismatch indicates that the systematic uncertainty in the sensitivity of a given instrument can lead to an uncertainty of 50–100 % in the methanol emissions measured by commonly used methods.

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