Chemical ionization mass spectrometry: A method of estimating reagent gas pressure in the ion source based on kinetic data

1979 ◽  
Vol 14 (9) ◽  
pp. 507-511 ◽  
Author(s):  
Richard A. Hancock ◽  
Raymond Walder ◽  
Helmut Weigel
Keyword(s):  
Mass Spectrometry ◽  
Kinetic Data ◽  
Chemical Ionization ◽  
Ion Source ◽  
Gas Pressure ◽  
Ionization Mass Spectrometry ◽  
Chemical Ionization Mass Spectrometry ◽  
Ionization Mass

scholarly journals Performance of a corona ion source for measurement of sulfuric acid by chemical ionization mass spectrometry

2011 ◽  
Vol 4 (3) ◽  
pp. 437-443 ◽  
Author(s):  
A. Kürten ◽  
L. Rondo ◽  
S. Ehrhart ◽  
J. Curtius
Keyword(s):  
Mass Spectrometry ◽  
Sulfuric Acid ◽  
Chemical Ionization ◽  
Ion Source ◽  
Ion Sources ◽  
Ionization Mass Spectrometry ◽  
Chemical Ionization Mass Spectrometry ◽  
Integration Time ◽  
Ionization Mass ◽  
H2so4 Concentration

Abstract. The performance of an ion source based on corona discharge has been studied. This source is used for the detection of gaseous sulfuric acid by chemical ionization mass spectrometry (CIMS) through the reaction of NO3– ions with H2SO4. The ion source is operated under atmospheric pressure and its design is similar to the one of a radioactive (americium-241) ion source which has been used previously. The results show that the detection limit for the corona ion source is sufficiently good for most applications. For an integration time of 1 min it is ~6 × 104 molecule cm−3 of H2SO4. In addition, only a small cross-sensitivity to SO2 has been observed for concentrations as high as 1 ppmv in the sample gas. This low sensitivity to SO2 is achieved even without the addition of an OH scavenger. When comparing the new corona ion source with the americium ion source for the same provided H2SO4 concentration, both ion sources yield almost identical values. These features make the corona ion source investigated here favorable over the more commonly used radioactive ion sources for most applications where H2SO4 is measured by CIMS.

scholarly journals Development of a chemical ionization mass spectrometry system for measurement of atmospheric OH radical

2020 ◽  
Author(s):  
Wei Pu ◽  
Zhouxing Zou ◽  
Weihao Wang ◽  
David Tanner ◽  
Zhe Wang ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Chemical Ionization ◽  
High Reactivity ◽  
Ion Source ◽  
Tropospheric Chemistry ◽  
Ionization Mass Spectrometry ◽  
Chemical Ionization Mass Spectrometry ◽  
Urban Site ◽  
Oh Radicals ◽  
Ionization Mass

Abstract. The hydroxyl radical (OH) is the most important oxidant in the atmosphere and plays a central role in tropospheric chemistry. Ambient OH is extremely difficult to measure because of its low concentration and high reactivity. We have developed and optimized a chemical ionization mass spectrometry (CIMS) system to measure OH based on ion-assisted mass spectrometry. A calibration unit was developed based on chemical actinometry to convert detected signals to OH concentration. Different types of ion sources (210Po and corona source) and scavenger gases (propane, C3F6, and NO2) were compared. Radioactive ion source (210Po foils) was chosen for lower detection limits, and propane was selected for high elimination efficiency and the negligible influence on the signal stability. The sensitivity of the CIMS instrument to OH radicals is influenced by the efficiencies of titration reaction, ion conversion, and ion transmission. Through adjusting their efficiencies by changing the flow rates and voltages, optimal sensitivity was determined. The background noise from OH interferences was reduced by adjusting the flow rate of scavenger gas. The CIMS system achieved a detection limit of ~ 0.15×106 molecules cm−3 (signal/noise = 2). The CIMS was then taken out to measure ambient OH radicals at an urban site in Hong Kong in April 2019. An obvious diurnal pattern of OH radicals was observed, with the highest concentration of ~ 6×106 molecules cm−3 at midday and the lowest concentration of ~ 0.25×106 molecules cm−3 at night, with an overall accuracy of about ±51 %. The results demonstrated the capability of our CIMS for OH measurements on clear days. The tests and results from our study provide a useful reference to other researchers who wish to develop and apply the CIMS technique to measure OH and other chemicals.

scholarly journals Performance of a corona ion source for measurement of sulfuric acid by chemical ionization mass spectrometry

2010 ◽  
Vol 3 (6) ◽  
pp. 5295-5312
Author(s):  
A. Kürten ◽  
L. Rondo ◽  
S. Ehrhart ◽  
J. Curtius
Keyword(s):  
Mass Spectrometry ◽  
Sulfuric Acid ◽  
Chemical Ionization ◽  
Ion Source ◽  
Ion Sources ◽  
Ionization Mass Spectrometry ◽  
Chemical Ionization Mass Spectrometry ◽  
Integration Time ◽  
Ionization Mass ◽  
H2so4 Concentration

Abstract. The performance of an ion source based on corona discharge has been studied. This source is used for the detection of gaseous sulfuric acid by chemical ionization mass spectrometry (CIMS) through the reaction of NO3– ions with H2SO4. The ion source is operated under atmospheric pressure and its design is similar to the one of a radioactive (Americium 241) ion source which has been used previously. Our results show that the detection limit for the corona ion source is sufficiently good for most applications. For an integration time of one minute it is ~6 × 104 molecules of H2SO4 per cm3. In addition, only a small cross-sensitivity to SO2 has been observed for concentrations as high as 1 ppmv in the sample gas. This low sensitivity to SO2 is achieved even without the addition of an OH scavenger. When comparing the new corona ion source with the americium ion source for the same provided H2SO4 concentration, both ion sources yield almost identical values. These features make the corona ion source investigated here favorable over the more commonly used radioactive ion sources for most applications where H2SO4 is measured by CIMS.

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