scholarly journals Clustering, methodology, and mechanistic insights into acetate chemical ionization using high-resolution time-of-flight mass spectrometry

2016 ◽  
Vol 9 (8) ◽  
pp. 3969-3986 ◽  
Author(s):  
Patrick Brophy ◽  
Delphine K. Farmer
Keyword(s):  
High Resolution ◽  
Atmospheric Pressure ◽  
Chemical Ionization ◽  
Time Of Flight ◽  
Ionization Mass ◽  
Resolution Time ◽  
Ionization Source ◽  
Targeted Analysis ◽  
The Impact

Abstract. We present a comprehensive characterization of cluster control and transmission through the Tofwerk atmospheric pressure interface installed on various chemical ionization time-of-flight mass spectrometers using authentic standards. This characterization of the atmospheric pressure interface allows for a detailed investigation of the acetate chemical ionization mechanisms and the impact of controlling these mechanisms on sensitivity, selectivity, and mass spectral ambiguity with the aim of non-targeted analysis. Chemical ionization with acetate reagent ions is controlled by a distribution of reagent ion-neutral clusters that vary with relative humidity and the concentration of the acetic anhydride precursor. Deprotonated carboxylic acids are primarily detected only if sufficient declustering is employed inside the atmospheric pressure interface. The configuration of a high-resolution time-of-flight chemical ionization mass spectrometer (HR-TOF-CIMS) using an acetate chemical ionization source for non-targeted analysis is discussed. Recent approaches and studies characterizing acetate chemical ionization as it applies to the HR-TOF-CIMS are evaluated in light of the work presented herein.

scholarly journals Clustering, Methodology, and Mechanistic Insights Into Acetate Chemical Ionization Using High-Resolution Time-of-Flight Mass Spectrometry

2016 ◽  
Author(s):  
Patrick Brophy ◽  
Delphine K. Farmer
Keyword(s):  
High Resolution ◽  
Atmospheric Pressure ◽  
Chemical Ionization ◽  
Time Of Flight ◽  
Ion Source ◽  
Resolution Time ◽  
Ionization Source ◽  
Targeted Analysis ◽  
The Impact

Abstract. We present a comprehensive characterization of cluster control and transmission through the Tofwerk atmospheric pressure interface installed on various chemical ionization time-of-flight mass spectrometers using authentic standards. This characterization of the atmospheric pressure interface allows for a detailed investigation of the acetate chemical ionization mechanisms and the impact of controlling these mechanisms on sensitivity, selectivity, and mass spectral ambiguity with the aim of non-targeted analysis. Chemical ionization with acetate reagent ions is controlled by a distribution of reagent ion-neutral clusters that vary with relative humidity and the concentration of acetic anhydride precursor. We show that the majority, if not all, ion-neutral chemistry occurs in the ion molecule reactor where incoming sample air mixes with the output of the ion source. Deprotonated carboxylic acids are primarily detected only if sufficient declustering is employed inside the atmospheric pressure interface. The configuration of a high-resolution time-of-flight chemical ionization mass spectrometer (HR-TOF-CIMS) using an acetate chemical ionization source for non-targeted analysis is discussed. Recent approaches and studies characterizing acetate chemical ionization as it applies to the HR-TOF-CIMS are evaluated in light of the work presented herein.

scholarly journals Detection of atmospheric gaseous amines and amides by a high resolution time-of-flight chemical ionization mass spectrometer with protonated ethanol reagent ions

2016 ◽  
Author(s):  
Lei Yao ◽  
Ming-Yi Wang ◽  
Xin-Ke Wang ◽  
Yi-Jun Liu ◽  
Hang-Fei Chen ◽  
...  
Keyword(s):  
High Resolution ◽  
Mass Spectrometer ◽  
Chemical Ionization ◽  
Time Of Flight ◽  
Integration Time ◽  
High Time Resolution ◽  
Ionization Mass ◽  
Industrial Emissions ◽  
Resolution Time ◽  
Ambient Measurements

Abstract. Amines and amides are important atmospheric organic-nitrogen compounds but high time resolution, highly sensitive, and simultaneous ambient measurements of these species are rather sparse. Here, we present the development of a high resolution time-of-flight chemical ionization mass spectrometer (HR-ToF-CIMS) method utilizing protonated ethanol as reagent ions to simultaneously detect atmospheric gaseous amines (C1 to C6) and amides (C1 to C6). This method possesses sensitivities of 5.6–19.4 Hz pptv−1 for amines and 3.8–38.0 Hz pptv−1 for amides under total reagent ion signals of ~ 0.32 MHz, and detection limits of 0.10–0.50 pptv for amines and 0.29–1.95 pptv for amides at 3σ of the background signal for a 1-min integration time, respectively. Controlled characterization in the laboratory indicates that relative humidity has significant influences on detection of amines and amides, whereas the presence of organics has no obvious effects. Ambient measurements of amines and amides utilizing this method were conducted from 25 July 2015 to 25 August 2015 in urban Shanghai, China. While the concentrations of amines ranged from a few pptv to hundreds of pptv, concentrations of amides varied from tens of pptv to a few ppbv. Among the C1- to C6-amines, the C2-amines were the dominant species with concentrations up to 130 pptv. For amides, the C3-amides (up to 8.7 ppb) were the most abundant species. The diurnal profiles of amines and amides suggest that in addition to the secondary formation of amides in the atmosphere, industrial emissions could be important sources of amides in urban Shanghai. During the campaign, photo-oxidation of amines and amides might be a main loss pathway for them in day time, and wet deposition was also an important sink.

An Iodide-Adduct High-Resolution Time-of-Flight Chemical-Ionization Mass Spectrometer: Application to Atmospheric Inorganic and Organic Compounds

2014 ◽  
Vol 48 (11) ◽  
pp. 6309-6317 ◽  
Author(s):  
Ben H. Lee ◽  
Felipe D. Lopez-Hilfiker ◽  
Claudia Mohr ◽  
Theo Kurtén ◽  
Douglas R. Worsnop ◽  
...  
Keyword(s):  
High Resolution ◽  
Organic Compounds ◽  
Mass Spectrometer ◽  
Chemical Ionization ◽  
Time Of Flight ◽  
Ionization Mass ◽  
Resolution Time ◽  
Inorganic And Organic

scholarly journals A switchable reagent ion high resolution time-of-flight chemical ionization mass spectrometer for real-time measurement of gas phase oxidized species: characterization from the 2013 Southern Oxidant and Aerosol Study

2015 ◽  
Vol 8 (3) ◽  
pp. 3199-3244 ◽  
Author(s):  
P. Brophy ◽  
D. K. Farmer
Keyword(s):  
High Resolution ◽  
Formic Acid ◽  
Gas Phase ◽  
Mass Spectrometer ◽  
Chemical Ionization ◽  
Time Of Flight ◽  
Ionization Mass ◽  
Resolution Time ◽  
Limit Of Quantification ◽  
Reduced Pressure

Abstract. A novel configuration of the Aerodyne high resolution time-of-flight chemical ionization mass spectrometer (HR-TOF-CIMS) as a switchable reagent ion (SRI) HR-TOF-CIMS is presented and described along with data collected at the Southern Oxidant and Aerosol Study (SOAS) during the summer of 2013. The calibration system and reduced pressure gas-phase inlet are characterized. The average limit of detection and limit of quantification for formic acid during SOAS are 82 and 863 ppt, respectively, corresponding to an average sensitivity of 13 ± 5 Hz ppt−1. Hourly background determinations and calibrations are shown to be essential for tracking instrument performance and accurately quantifying formic acid. Maximum daytime formic acid concentrations of 10 ppb are reported during SOAS, and a strong diel cycle is observed leading to night time concentrations below the limit of quantification. Other species presented exhibit diel behavior similar to formic acid. The concept of the mass defect enhancement plot and the use of signal-to-noise are described in detail as a method for investigating HR-TOF-CIMS spectra in an effort to reduce data complexity.

scholarly journals Chemical characterization of secondary organic aerosol at a rural site in the southeastern US: insights from simultaneous high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) and FIGAERO chemical ionization mass spectrometer (CIMS) measurements

2020 ◽  
Vol 20 (14) ◽  
pp. 8421-8440
Author(s):  
Yunle Chen ◽  
Masayuki Takeuchi ◽  
Theodora Nah ◽  
Lu Xu ◽  
Manjula R. Canagaratna ◽  
...  
Keyword(s):  
High Resolution ◽  
Mass Spectrometer ◽  
Chemical Ionization ◽  
Secondary Organic Aerosol ◽  
Time Of Flight ◽  
Organic Aerosol ◽  
Ionization Mass ◽  
Resolution Time ◽  
Aerosol Mass Spectrometer ◽  
Aerosol Mass

Abstract. The formation and evolution of secondary organic aerosol (SOA) were investigated at Yorkville, GA, in late summer (mid-August to mid-October 2016). The organic aerosol (OA) composition was measured using two online mass spectrometry instruments, the high-resolution time-of-flight aerosol mass spectrometer (AMS) and the Filter Inlet for Gases and AEROsols coupled to a high-resolution time-of-flight iodide-adduct chemical ionization mass spectrometer (FIGAERO-CIMS). Through analysis of speciated organics data from FIGAERO-CIMS and factorization analysis of data obtained from both instruments, we observed notable SOA formation from isoprene and monoterpenes during both day and night. Specifically, in addition to isoprene epoxydiol (IEPOX) uptake, we identified isoprene SOA formation from non-IEPOX pathways and isoprene organic nitrate formation via photooxidation in the presence of NOx and nitrate radical oxidation. Monoterpenes were found to be the most important SOA precursors at night. We observed significant contributions from highly oxidized acid-like compounds to the aged OA factor from FIGAERO-CIMS. Taken together, our results showed that FIGAERO-CIMS measurements are highly complementary to the extensively used AMS factorization analysis, and together they provide more comprehensive insights into OA sources and composition.

scholarly journals Detection of atmospheric gaseous amines and amides by a high-resolution time-of-flight chemical ionization mass spectrometer with protonated ethanol reagent ions

2016 ◽  
Vol 16 (22) ◽  
pp. 14527-14543 ◽  
Author(s):  
Lei Yao ◽  
Ming-Yi Wang ◽  
Xin-Ke Wang ◽  
Yi-Jun Liu ◽  
Hang-Fei Chen ◽  
...  
Keyword(s):  
High Resolution ◽  
Mass Spectrometer ◽  
Chemical Ionization ◽  
Time Of Flight ◽  
Integration Time ◽  
High Time Resolution ◽  
Ionization Mass ◽  
Industrial Emissions ◽  
Resolution Time ◽  
Ambient Measurements

Abstract. Amines and amides are important atmospheric organic-nitrogen compounds but high time resolution, highly sensitive, and simultaneous ambient measurements of these species are rather sparse. Here, we present the development of a high-resolution time-of-flight chemical ionization mass spectrometer (HR-ToF-CIMS) method, utilizing protonated ethanol as reagent ions to simultaneously detect atmospheric gaseous amines (C1 to C6) and amides (C1 to C6). This method possesses sensitivities of 5.6–19.4 Hz pptv−1 for amines and 3.8–38.0 Hz pptv−1 for amides under total reagent ion signals of  ∼  0.32 MHz. Meanwhile, the detection limits were 0.10–0.50 pptv for amines and 0.29–1.95 pptv for amides at 3σ of the background signal for a 1 min integration time. Controlled characterization in the laboratory indicates that relative humidity has significant influences on the detection of amines and amides, whereas the presence of organics has no obvious effects. Ambient measurements of amines and amides utilizing this method were conducted from 25 July to 25 August 2015 in urban Shanghai, China. While the concentrations of amines ranged from a few parts per trillion by volume to hundreds of parts per trillion by volume, concentrations of amides varied from tens of parts per trillion by volume to a few parts per billion by volume. Among the C1- to C6-amines, the C2-amines were the dominant species with concentrations up to 130 pptv. For amides, the C3-amides (up to 8.7 ppb) were the most abundant species. The diurnal and backward trajectory analysis profiles of amides suggest that in addition to the secondary formation of amides in the atmosphere, industrial emissions could be important sources of amides in urban Shanghai. During the campaign, photo-oxidation of amines and amides might be a main loss pathway for them in daytime, and wet deposition was also an important sink.

scholarly journals A switchable reagent ion high resolution time-of-flight chemical ionization mass spectrometer for real-time measurement of gas phase oxidized species: characterization from the 2013 southern oxidant and aerosol study

2015 ◽  
Vol 8 (7) ◽  
pp. 2945-2959 ◽  
Author(s):  
P. Brophy ◽  
D. K. Farmer
Keyword(s):  
High Resolution ◽  
Formic Acid ◽  
Gas Phase ◽  
Mass Spectrometer ◽  
Chemical Ionization ◽  
Time Of Flight ◽  
Ionization Mass ◽  
Resolution Time ◽  
Limit Of Quantification ◽  
Reduced Pressure

Abstract. A novel configuration of the Aerodyne high resolution time-of-flight chemical ionization mass spectrometer (HR-TOF-CIMS) as a switchable reagent ion (SRI) HR-TOF-CIMS is presented and described along with data collected at the Southern Oxidant and Aerosol Study (SOAS) during the summer of 2013. The calibration system and reduced pressure gas phase inlet are characterized. The average limit of detection and limit of quantification for formic acid during SOAS are 82 and 863 ppt, respectively, corresponding to an average sensitivity of 13 ± 5 Hz ppt−1. Hourly background determinations and calibrations are shown to be essential for tracking instrument performance and accurately quantifying formic acid. Maximum daytime formic acid concentrations of 10 ppb are reported during SOAS, and a strong diel cycle is observed leading to nighttime concentrations below the limit of quantification. Other species presented exhibit diel behavior similar to formic acid. The concept of the mass defect enhancement plot and the use of signal-to-noise are described in detail as a method for investigating HR-TOF-CIMS spectra in an effort to reduce data complexity.

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