scholarly journals Measurements of hydroperoxy radicals (HO<sub>2</sub>) at atmospheric concentrations using bromide chemical ionisation mass spectrometry

2019 ◽  
Vol 12 (2) ◽  
pp. 891-902 ◽  
Author(s):  
Sascha R. Albrecht ◽  
Anna Novelli ◽  
Andreas Hofzumahaus ◽  
Sungah Kang ◽  
Yare Baker ◽  
...  
Keyword(s):  
Water Vapour ◽  
Mass Spectrometer ◽  
Ion Source ◽  
Detection Sensitivity ◽  
Detection Methods ◽  
Integration Time ◽  
Key Species ◽  
Atmospheric Concentrations ◽  
Chemical Ionisation ◽  
Ionisation Mass

Abstract. Hydroxyl and hydroperoxy radicals are key species for the understanding of atmospheric oxidation processes. Their measurement is challenging due to their high reactivity; therefore, very sensitive detection methods are needed. Within this study, the measurement of hydroperoxy radicals (HO2) using chemical ionisation combined with a high-resolution time-of-flight mass spectrometer (Aerodyne Research Inc.) employing bromide as the primary ion is presented. The sensitivity reached is equal to 0.005×108 HO2 cm−3 for 106 cps of bromide and 60 s of integration time, which is below typical HO2 concentrations found in the atmosphere. The detection sensitivity of the instrument is affected by the presence of water vapour. Therefore, a water-vapour-dependent calibration factor that decreases approximately by a factor of 2 if the water vapour mixing ratio increases from 0.1 % to 1.0 % needs to be applied. An instrumental background, most likely generated by the ion source that is equivalent to a HO2 concentration of (1.5±0.2)×108 molecules cm−3, is subtracted to derive atmospheric HO2 concentrations. This background can be determined by overflowing the inlet with zero air. Several experiments were performed in the atmospheric simulation chamber SAPHIR at the Forschungszentrum Jülich to test the instrument performance in comparison to the well-established laser-induced fluorescence (LIF) technique for measurements of HO2. A highly linear correlation coefficient of R2=0.87 is achieved. The slope of the linear regression of 1.07 demonstrates the good absolute agreement of both measurements. Chemical conditions during experiments allowed for testing the instrument's behaviour in the presence of atmospheric concentrations of H2O, NOx, and O3. No significant interferences from these species were observed. All of these facts demonstrate a reliable measurement of HO2 by the chemical ionisation mass spectrometer presented.

scholarly journals Measurements of hydroperoxy radicals (HO<sub>2</sub>) at atmospheric concentrations using bromide chemical ionization mass spectrometry

2018 ◽  
Author(s):  
Sascha R. Albrecht ◽  
Anna Novelli ◽  
Andreas Hofzumahaus ◽  
Sungah Kang ◽  
Yare Baker ◽  
...  
Keyword(s):  
Water Vapor ◽  
Mass Spectrometer ◽  
Chemical Ionization ◽  
Limit Of Detection ◽  
Ion Source ◽  
Detection Sensitivity ◽  
Detection Methods ◽  
Ionization Mass ◽  
Key Species ◽  
Atmospheric Concentrations

Abstract. Hydroxyl and hydroperoxy radicals are key species for the understanding of atmospheric oxidation processes. Their measurement is challenging due to their high reactivity, therefore very sensitive detection methods are needed. Within this study, the measurement of hydroperoxy radicals (HO2) using chemical ionization combined with an high resolution time of flight mass spectrometer (Aerodyne Research Inc.) employing bromide as primary ion is presented. The 1σ limit of detection of 4.5 × 107 molecules cm−3 for a 60 s measurement is below typical HO2 concentrations found in the atmosphere. The detection sensitivity of the instrument is affected by the presence of water vapor. Therefore, a water vapor dependent calibration factor that decreases approximately by a factor of 2 if the water vapor mixing ratio increases from 0.1 to 1.0 % needs to be applied. An instrumental background most likely generated by the ion source that is equivalent to a HO2 concentration of 1.5 ± 0.2 × 108 molecules cm−3 is subtracted to derive atmospheric HO2 concentrations. This background can be determined by overflowing the inlet with zero air. Several experiments were performed in the atmospheric simulation chamber SAPHIR at the Forschungszentrum Jülich to test the instrument performance by comparison to the well-established laser-induced fluorescence (LIF) technique for measurements of HO2. A high linear correlation coefficient of R2 = 0.87 is achieved. The slope of the linear regression of 1.07 demonstrates the good absolute agreement of both measurements. Chemical conditions during 15 experiments allowed testing the instrument’s behavior in the presence of atmospheric concentrations of H2O, NOx and O3. No significant interferences from these species were observed. All these facts are demonstrating a reliable measurement of HO2 by the chemical ionization mass spectrometer presented.

Chemical ionisation mass spectrometry for the measurement of atmospheric amines

2012 ◽  
Vol 9 (3) ◽  
pp. 190 ◽  
Author(s):  
Huan Yu ◽  
Shan-Hu Lee
Keyword(s):  
Real Time ◽  
Gas Phase ◽  
Mass Spectrometer ◽  
Detection Limits ◽  
Integration Time ◽  
Fast Time ◽  
Aerosol Formation ◽  
Secondary Aerosol ◽  
Chemical Ionisation ◽  
Ionisation Mass

Environmental contextAmines are of interest to atmospheric chemistry as they may be important gas-phase precursors for secondary aerosol formation. We describe a mass spectrometer for real-time in-situ measurements of gaseous alkyl amines in the atmosphere. This measurement technique will help to evaluate the contribution of amines to the formation of secondary aerosols, including secondary organic aerosol and new particle formation. AbstractWe describe a chemical ionisation mass spectrometer (CIMS) for the ambient measurement of amines, known as important gas-phase precursors for secondary aerosol formation. Protonated ethanol or acetone ions were used as ionisation reagents to selectively detect high proton affinity base compounds (e.g. amines and NH3), thereby minimising interferences from other atmospheric gaseous organic compounds. With ethanol as ionisation reagent (~3 × 105 Hz of ion signals), the CIMS showed similar sensitivities (2.1–8.7 Hz pptv–1) and detection limits (7–41 pptv with a 1-min integration time) for NH3 and several atmospherically relevant key amine compounds containing one to six carbon atoms (C1- to C6-amines and their isomers). The CIMS background signals of the six amines ranged from 9 to 40 pptv, much lower than ~930 pptv for NH3. The CIMS response times were between 13 and 26 s for these amines. The unique combination of the fast time response, high sensitivities and low detection limits allows the use of this CIMS for real time measurements of atmospheric trace amines. During the ambient measurement made in Kent, OH, in November 2011, the measured mixing ratios of C2- and C3-amines were 8 ± 3 (mean ± 1 standard deviation) and 16 ± 7 pptv, whereas those of NH3 were 517 ± 259 pptv.

Improved detection sensitivity for heavy trace elements using a miniature laser ablation ionisation mass spectrometer

2017 ◽  
Vol 32 (11) ◽  
pp. 2182-2188 ◽  
Author(s):  
R. Wiesendanger ◽  
M. Tulej ◽  
A. Riedo ◽  
S. Frey ◽  
H. Shea ◽  
...  
Keyword(s):  
Trace Elements ◽  
Laser Ablation ◽  
Mass Spectrometer ◽  
Detection Sensitivity ◽  
Laser Spectrometer ◽  
Lunar Meteorite ◽  
Ionisation Mass ◽  
Ionisation Mass Spectrometer

Detecting heavy trace elements with a miniature laser spectrometer on a lunar meteorite.

Field Ionisation Studies Using a Double Focussing Mass Spectrometer

1966 ◽  
Vol 21 (6) ◽  
pp. 776-779 ◽  
Author(s):  
J. H. Beynon ◽  
A. E. Fontaine ◽  
B. E. Job
Keyword(s):  
Mass Spectrometer ◽  
Single Molecule ◽  
Mass Spectra ◽  
Ion Source ◽  
Energy Spread ◽  
Small Energy ◽  
Intense Field ◽  
Ionisation Mass

Intense field ionisation mass spectra have been obtained with an A.E.I. M.S.7 mass spectrometer, used with very simple modifications to the ion source.Some features of the spectra of a variety of compounds are given and the spectrum of acetone is discussed in detail. A special feature of this spectrum is the variety of ions with a mass greater than that of a single molecule.The relatively small energy spread of the field ion source enabled resolving powers, higher than those possible with a spark source, to be obtained. Multiplets occurring in the spectra were easily resolved.

scholarly journals Chemical ionisation quadrupole mass spectrometer with an electrical discharge ion source for atmospheric trace gas measurement

2018 ◽  
Author(s):  
Philipp G. Eger ◽  
Frank Helleis ◽  
Gerhard Schuster ◽  
Gavin J. Phillips ◽  
Jos Lelieveld ◽  
...  
Keyword(s):  
Acetic Acid ◽  
Mass Spectrometer ◽  
Ion Source ◽  
Quadrupole Mass Spectrometer ◽  
Rf Discharge ◽  
Data Sets ◽  
Quadrupole Mass ◽  
Ion Chemistry ◽  
Ion Molecule Reactions ◽  
Chemical Ionisation

Abstract. We present a Chemical Ionisation Quadrupole Mass Spectrometer (CI-QMS) with radio-frequency (RF) discharge ion source through N2/CH3I as source of primary ions. In addition to the expected detection of PAN, peracetic acid and ClNO2 through well-established ion-molecule-reactions with I- and its water cluster, the instrument is also sensitive to SO2, HCl and acetic acid (CH3C(O)OH) through additional ion chemistry unique for our ion source. We present ionisation schemes for detection of SO2, HCl and acetic acid along with illustrative data sets from three different field campaigns underlining the potential of the CI-QMS with an RF discharge ion source as an alternative to 210Po. The additional sensitivity to SO2 and HCl makes the CI-QMS suitable for investigating the role of sulphur and chlorine chemistry in the polluted marine and coastal boundary layer.

Effect of ion source pressure on ion formation of carbamates in particle-beam chemical-ionisation mass spectrometry

1995 ◽  
Vol 712 (1) ◽  
pp. 21-30 ◽  
Author(s):  
M. Honing ◽  
D. Barceló ◽  
M.E. Jager ◽  
J. Slobodnik ◽  
B.L.M. van Baar ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Particle Beam ◽  
Ion Source ◽  
Source Pressure ◽  
Ion Formation ◽  
Ionisation Mass Spectrometry ◽  
Chemical Ionisation ◽  
Ionisation Mass

scholarly journals Airborne observations of formic acid using a chemical ionisation mass spectrometer

2011 ◽  
Vol 4 (5) ◽  
pp. 5807-5835 ◽  
Author(s):  
M. Le Breton ◽  
M. R. McGillen ◽  
J. B. A. Muller ◽  
A. Bacak ◽  
D. E. Shallcross ◽  
...  
Keyword(s):  
Formic Acid ◽  
Mass Spectrometer ◽  
Limit Of Detection ◽  
Lower Boundary ◽  
Standard Addition ◽  
Airborne Measurements ◽  
Mixing Ratios ◽  
Chemical Ionisation ◽  
Ionisation Mass ◽  
Ionisation Mass Spectrometer

Abstract. The first airborne measurements of formic acid mixing ratios over the United Kingdom were measured on the FAAM BAe-146 research aircraft on the 16 March 2010 with a chemical ionisation mass spectrometer using I− reagent ions. The I− ionisation scheme was able to measure formic acid mixing ratios at 1 Hz in the lower boundary layer. In-flight standard addition calibrations from a formic acid source were used to determine the instrument sensitivity of 35±6 ion counts pptv−1 s−1 and a limit of detection of 25 pptv. Routine measurements were made through a scrubbed inlet to determine the instrumental background. Three plumes of formic acid were observed over the UK, originating from London, Humberside and Tyneside. The London plume had the highest formic acid mixing ratio throughout the flight, peaking at 358 pptv. No significant correlations of formic acid with NOx and Ozone were found. A trajectory model was employed to determine the sources of the plumes and compare modelled mixing ratios with measured values. The model underestimated formic acid concentrations by up to a factor of 2. This is explained by missing sources in the model, considered to be primary emissions of formic acid of mainly anthropogenic origin and lack of precursor emissions, such as isoprene, from biogenic sources.

scholarly journals Development and characterization of a High-Temperature Proton-Transfer-Reaction Mass Spectrometer (HT-PTR-MS)

2010 ◽  
Vol 3 (3) ◽  
pp. 537-544 ◽  
Author(s):  
T. Mikoviny ◽  
L. Kaser ◽  
A. Wisthaler
Keyword(s):  
High Temperature ◽  
Proton Transfer ◽  
Mass Spectrometer ◽  
Transfer Reaction ◽  
Response Times ◽  
Proton Transfer Reaction ◽  
Ion Source ◽  
Reaction Mass ◽  
Integration Time ◽  
Ion Drift

Abstract. We have developed a High-Temperature Proton-Transfer-Reaction Mass Spectrometer (HT-PTR-MS) in which both the ion source and the ion drift tube can be continuously operated at temperatures up to 250 °C. The instrument was characterized in a high E/N-mode (130 Td) and in a low E/N-mode (87 Td) at an operating temperature of 200 °C. Instrumental sensitivities and 2σ-detection limits were on the order of 50–110 cps/ppb and 100 ppt (1 s signal integration time), respectively. The HT-PTR-MS is primarily intended for measuring "sticky" or semi-volatile trace gases. Alternatively, it may be coupled to a particle collection/thermal desorption apparatus to measure particle-bound organics in near real-time. In view of these applications, we have measured instrumental response times for a series of reference compounds. 1/e2-response times for dimethyl sulfoxide, ammonia and monoethanolamine were in the sub-second to second regime. 1/e2-response times for levoglucosan, oxalic acid and cis-pinonic acid ranged from 8 to 370 s.

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