scholarly journals A new method to quantify particulate sodium and potassium salts (nitrate, chloride, and sulfate) by thermal desorption aerosol mass spectrometry

2021 ◽  
Author(s):  
Yuya Kobayashi ◽  
Nobuyuki Takegawa
Keyword(s):  
Mass Spectrometer ◽  
Thermal Desorption ◽  
Carbon Dioxide Laser ◽  
Potassium Nitrate ◽  
Sea Salt ◽  
Potassium Sulfate ◽  
New Method ◽  
Desorption Temperature ◽  
Aerosol Mass ◽  
Temporal Profiles

Abstract. The reaction of sea salt (or biomass burning) particles with sulfuric acid and nitric acid leads to the displacement of chloride relative to sodium (or potassium). We have developed a new particle mass spectrometer to quantify non-refractory and refractory sulfate aerosols (referred to as refractory aerosol thermal desorption mass spectrometer: rTDMS). The combination of a graphite particle collector and a carbon dioxide laser enables high desorption temperature (up to 930 °C). Ion signals originating from evolved gas molecules are detected by a quadrupole mass spectrometer. Here we propose a new method to quantify the mass concentrations of sodium nitrate (NaNO3: SN), sodium chloride (NaCl: SC), sodium sulfate (Na2SO4: SS), potassium nitrate (KNO3: PN), potassium chloride (KCl: PC), and potassium sulfate (K2SO4 : PS) particles by using the rTDMS. Laboratory experiments were performed to test the sensitivities of the rTDMS to various types of particles. We measured ion signals originating from single-component particles for each compound, and found a good linearity (r2 > 0.8) between the major ion signals and mass loadings. We also measured ion signals originating from internally mixed SN + SC + SS (or PN + PC + PS) particles, and found that the temporal profiles of ion signals at m/z 23 (or 39) were characterized by three sequential peaks associated with the evolution of the desorption temperature. We tested potential interferences in the quantification of sea salt particles under real-world conditions by artificially generating "modified" sea salt particles from a mixture of diluted seawater and SS/SN solution. Based on these experimental results, the applicability of the rTDMS to ambient measurements of sea salt particles is discussed.

scholarly journals Organic and inorganic decomposition products from the thermal desorption of atmospheric particles

2015 ◽  
Vol 8 (12) ◽  
pp. 13377-13421 ◽  
Author(s):  
B. J. Williams ◽  
Y. Zhang ◽  
X. Zuo ◽  
R. E. Martinez ◽  
M. J. Walker ◽  
...  
Keyword(s):  
Thermal Decomposition ◽  
Mass Spectrometer ◽  
Thermal Desorption ◽  
Sample Introduction ◽  
Organic Nitrate ◽  
Aerosol Composition ◽  
Decomposition Products ◽  
Aerosol Mass ◽  
Thermal Decomposition Products ◽  
Mass Concentrations

Abstract. Atmospheric aerosol composition is often analyzed using thermal desorption techniques to evaporate samples and deliver organic or inorganic molecules to various designs of detectors for identification and quantification. The organic aerosol (OA) fraction is composed of thousands of individual compounds, some with nitrogen- and sulfur-containing functionality, and often contains oligomeric material, much of which may be susceptible to decomposition upon heating. Here we analyze thermal decomposition products as measured by a thermal desorption aerosol gas chromatograph (TAG) capable of separating thermal decomposition products from thermally stable molecules. The TAG impacts particles onto a collection and thermal desorption (CTD) cell, and upon completion of sample collection, heats and transfers the sample in a helium flow up to 310 °C. Desorbed molecules are refocused at the head of a GC column that is held at 45 °C and any volatile decomposition products pass directly through the column and into an electron impact quadrupole mass spectrometer (MS). Analysis of the sample introduction (thermal decomposition) period reveals contributions of NO+ (m/z 30), NO2+ (m/z 46), SO+ (m/z 48), and SO2+ (m/z 64), derived from either inorganic or organic particle-phase nitrate and sulfate. CO2+ (m/z 44) makes up a major component of the decomposition signal, along with smaller contributions from other organic components that vary with the type of aerosol contributing to the signal (e.g., m/z 53, 82 observed here for isoprene-derived secondary OA). All of these ions are important for ambient aerosol analyzed with the aerosol mass spectrometer (AMS), suggesting similarity of the thermal desorption processes in both instruments. Ambient observations of these decomposition products compared to organic, nitrate, and sulfate mass concentrations measured by an AMS reveal good correlation, with improved correlations for OA when compared to the AMS oxygenated OA (OOA) component. TAG signal found in the traditional compound elution time period reveals higher correlations with AMS hydrocarbon-like OA (HOA) combined with the fraction of OOA that is less oxygenated. Potential to quantify nitrate and sulfate aerosol mass concentrations using the TAG system is explored through analysis of ammonium sulfate and ammonium nitrate standards. While chemical standards display a linear response in the TAG system, re-desorptions of the CTD cell following ambient sample analysis shows some signal carryover on sulfate and organics, and new desorption methods should be developed to improve throughput. Future standards should be composed of complex organic/inorganic mixtures, similar to what is found in the atmosphere, and perhaps will more accurately account for any aerosol mixture effects on compositional quantification.

scholarly journals Thermal desorption metastable atom bombardment ionization aerosol mass spectrometer

2011 ◽  
Vol 303 (2-3) ◽  
pp. 164-172 ◽  
Author(s):  
Carly B. Robinson ◽  
Joel R. Kimmel ◽  
Donald E. David ◽  
John T. Jayne ◽  
Achim Trimborn ◽  
...  
Keyword(s):  
Mass Spectrometer ◽  
Thermal Desorption ◽  
Metastable Atom ◽  
Aerosol Mass Spectrometer ◽  
Aerosol Mass

scholarly journals Studies of aerosol at a coastal site using two aerosol mass spectrometry instruments and identification of biogenic particle types

2005 ◽  
Vol 5 (5) ◽  
pp. 10799-10838 ◽  
Author(s):  
M. Dall’Osto ◽  
R. M. Harrison ◽  
H. Furutani ◽  
K. A. Prather ◽  
H. Coe ◽  
...  
Keyword(s):  
Mass Spectrometer ◽  
Atmospheric Chemistry ◽  
Mass Spectra ◽  
Sea Salt ◽  
Aerosol Mass Spectrometer ◽  
Mass Spectral ◽  
Aerosol Mass ◽  
Aerosol Mass Spectrometry ◽  
Neural Network Algorithm ◽  
Individual Particles

Abstract. During August 2004 an Aerosol Time-of-Flight Mass Spectrometer (TSI ATOFMS Model 3800-100) and an Aerodyne Aerosol Mass Spectrometer (AMS) were deployed at Mace Head during the NAMBLEX campaign. Single particle data (size, positive and negative mass spectra) from the ATOFMS were imported into ART 2a, a neural network algorithm, which assigns individual particles to clusters on the basis of their mass spectral similarities. Results are very consistent with previous time consuming manual classifications (Dall'Osto et al., 2004). Three broad classes were found: sea-salt, dust and carbon-containing particles, with a number of sub-classes within each. The Aerodyne (AMS) instrument was also used during NAMBLEX, providing online, real time measurements of the mass of non-refractory components of aerosol particles as function of their size. The ATOFMS detected a type of particle not identified in our earlier analysis, with a strong signal at m/z 24, likely due to magnesium. This type of particle was detected during the same periods as pure unreacted sea salt particles and is thought to be biogenic, originating from the sea surface. AMS data are consistent with this interpretation, showing an additional organic peak in the corresponding size range at times when the Mg-rich particles are detected. The work shows the ATOFMS and AMS to be largely complementary, and to provide a powerful instrumental combination in studies of atmospheric chemistry.

scholarly journals Organic and inorganic decomposition products from the thermal desorption of atmospheric particles

2016 ◽  
Vol 9 (4) ◽  
pp. 1569-1586 ◽  
Author(s):  
Brent J. Williams ◽  
Yaping Zhang ◽  
Xiaochen Zuo ◽  
Raul E. Martinez ◽  
Michael J. Walker ◽  
...  
Keyword(s):  
Thermal Decomposition ◽  
Mass Spectrometer ◽  
Thermal Desorption ◽  
Sample Introduction ◽  
Organic Nitrate ◽  
Aerosol Composition ◽  
Decomposition Products ◽  
Aerosol Mass ◽  
Thermal Decomposition Products ◽  
Mass Concentrations

Abstract. Atmospheric aerosol composition is often analyzed using thermal desorption techniques to evaporate samples and deliver organic or inorganic molecules to various designs of detectors for identification and quantification. The organic aerosol (OA) fraction is composed of thousands of individual compounds, some with nitrogen- and sulfur-containing functionality and, often contains oligomeric material, much of which may be susceptible to decomposition upon heating. Here we analyze thermal decomposition products as measured by a thermal desorption aerosol gas chromatograph (TAG) capable of separating thermal decomposition products from thermally stable molecules. The TAG impacts particles onto a collection and thermal desorption (CTD) cell, and upon completion of sample collection, heats and transfers the sample in a helium flow up to 310 °C. Desorbed molecules are refocused at the head of a gas chromatography column that is held at 45 °C and any volatile decomposition products pass directly through the column and into an electron impact quadrupole mass spectrometer. Analysis of the sample introduction (thermal decomposition) period reveals contributions of NO+ (m/z 30), NO2+ (m/z 46), SO+ (m/z 48), and SO2+ (m/z 64), derived from either inorganic or organic particle-phase nitrate and sulfate. CO2+ (m/z 44) makes up a major component of the decomposition signal, along with smaller contributions from other organic components that vary with the type of aerosol contributing to the signal (e.g., m/z 53, 82 observed here for isoprene-derived secondary OA). All of these ions are important for ambient aerosol analyzed with the aerosol mass spectrometer (AMS), suggesting similarity of the thermal desorption processes in both instruments. Ambient observations of these decomposition products compared to organic, nitrate, and sulfate mass concentrations measured by an AMS reveal good correlation, with improved correlations for OA when compared to the AMS oxygenated OA (OOA) component. TAG signal found in the traditional compound elution time period reveals higher correlations with AMS hydrocarbon-like OA (HOA) combined with the fraction of OOA that is less oxygenated. Potential to quantify nitrate and sulfate aerosol mass concentrations using the TAG system is explored through analysis of ammonium sulfate and ammonium nitrate standards. While chemical standards display a linear response in the TAG system, redesorptions of the CTD cell following ambient sample analysis show some signal carryover on sulfate and organics, and new desorption methods should be developed to improve throughput. Future standards should be composed of complex organic/inorganic mixtures, similar to what is found in the atmosphere, and perhaps will more accurately account for any aerosol mixture effects on compositional quantification.

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