scholarly journals Development of an automatic linear calibration method for high-resolution single-particle mass spectrometry: improved chemical species identification for atmospheric aerosols

2020 ◽  
Vol 13 (8) ◽  
pp. 4111-4121
Author(s):  
Shengqiang Zhu ◽  
Lei Li ◽  
Shurong Wang ◽  
Mei Li ◽  
Yaxi Liu ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
High Resolution ◽  
Single Particle ◽  
Mass Spectra ◽  
Calibration Method ◽  
Particle Mass ◽  
Sea Spray ◽  
Linear Calibration ◽  
Ambient Aerosol ◽  
Sea Spray Aerosol

Abstract. The mass resolution of laser desorption ionization (LDI) single-particle aerosol mass spectrometry (SPAMS) is usually low (∼500), which has been greatly improved by the recent development of the delayed ion extraction technique. However, due to large fluctuations among LDI processes during each laser shot, accurate calibration of the mass-to-charge ratio for high-resolution SPAMS (HR-SPAMS) spectra is challenging. Here we developed an automatic linear calibration method to improve the accuracy of mass-to-charge (m∕z) measurement for single atmospheric aerosol particles. Laboratory-generated sea spray aerosol and atmospheric ambient aerosol were tested. After the calibration, the fluctuation ranges of the reference ions' (e.g., Pb+ and SO4+) m∕z reaches ±0.018 for sea spray aerosol and ±0.024 for ambient aerosol in average mass spectra. With such m∕z accuracy, the HR-SPAMS spectra of sea spray aerosol can easily identify elemental compositions of organic peaks, such as Cx, CxHy and CxHyOz. While the chemical compositions of ambient aerosols are more complicated, CxHy, CxHyOz and CNO peaks can also be identified based on their accurate mass. With the improved resolution, the time series of peaks with small m∕z differences can be separated and measured. In addition, it is also found that applying high-resolution data with enhanced mass calibration can significantly affect particle classification (identification) using the ART-2a algorithm, which classify particles based on similarities among single-particle mass spectra.

scholarly journals Development of an Automatic Linear Calibration Method for High Resolution Single Particle Mass Spectrometry: Improved Chemical Species Identification for Atmospheric Aerosols

2020 ◽  
Author(s):  
Shengqiang Zhu ◽  
Lei Li ◽  
Shurong Wang ◽  
Mei Li ◽  
Yaxi Liu ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
High Resolution ◽  
Single Particle ◽  
Mass Spectra ◽  
Calibration Method ◽  
Particle Mass ◽  
Sea Spray ◽  
Linear Calibration ◽  
Ambient Aerosol ◽  
Sea Spray Aerosol

Abstract. The mass resolution of laser desorption ionization (LDI) single particle aerosol mass spectrometry (SPAMS) is usually low (~500), which has been greatly improved by recent development of delayed ion extraction technique. However, due to large fluctuations among LDI processes during each laser shot, accurate calibration of mass-to-charge ratio for high resolution SPAMS spectra is challenging. Here we developed an automatic linear calibration method to improve the accuracy of mass-to-charge (m/z) measurement for single atmospheric aerosol particles. Laboratory generated sea spray aerosol and atmospheric ambient aerosol were tested. After the calibration, the fluctuation ranges of the reference ions (e.g. Pb+ and SO4+) m/z reaches ±0.018 for sea spray aerosol and ±0.024 for ambient aerosol in average mass spectra. With such m/z accuracy, the HR-SPAMS spectra of sea spray aerosol can easily identify elemental compositions of organic peaks, such as Cx, CxHy and CxHyOz. While the chemical compositions of ambient aerosols are more complicated, CxHy, CxHyOz and CNO peaks can also be identified based on their accurate mass. With the improved resolution, the time series of peaks with small m/z differences can be separated and measured. In addition, it is also found that applying high resolution data with enhanced mass calibration can significantly affect particle classification (identification) using the ART-2a algorism, which classify particles based on similarities among single particle mass spectra.

Thermal desorption single particle mass spectrometry of ambient aerosol in Shanghai

2015 ◽  
Vol 123 ◽  
pp. 407-414 ◽  
Author(s):  
Jinghao Zhai ◽  
Xinning Wang ◽  
Jingyan Li ◽  
Tingting Xu ◽  
Hong Chen ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Thermal Desorption ◽  
Single Particle ◽  
Particle Mass ◽  
Ambient Aerosol ◽  
Single Particle Mass Spectrometry

scholarly journals Exploring femtosecond laser ablation in single-particle aerosol mass spectrometry

2018 ◽  
Vol 11 (7) ◽  
pp. 4345-4360 ◽  
Author(s):  
Ramakrishna Ramisetty ◽  
Ahmed Abdelmonem ◽  
Xiaoli Shen ◽  
Harald Saathoff ◽  
Thomas Leisner ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Laser Ablation ◽  
Power Density ◽  
Single Particle ◽  
Laser Power ◽  
Mass Spectra ◽  
Laser Power Density ◽  
Particle Mass ◽  
Mass Spectral ◽  
Fs Laser

Abstract. Size, composition, and mixing state of individual aerosol particles can be analysed in real time using single-particle mass spectrometry (SPMS). In SPMS, laser ablation is the most widely used method for desorption and ionization of particle components, often realizing both in one single step. Excimer lasers are well suited for this task due to their relatively high power density (107–1010 W cm−2) in nanosecond (ns) pulses at ultraviolet (UV) wavelengths and short triggering times. However, varying particle optical properties and matrix effects make a quantitative interpretation of this analytical approach challenging. In atmospheric SPMS applications, this influences both the mass fraction of an individual particle that is ablated, as well as the resulting mass spectral fragmentation pattern of the ablated material. The present study explores the use of shorter (femtosecond, fs) laser pulses for atmospheric SPMS. Its objective is to assess whether the higher laser power density of the fs laser leads to a more complete ionization of the entire particle and higher ion signal and thus improvement in the quantitative abilities of SPMS. We systematically investigate the influence of power density and pulse duration on airborne particle (polystyrene latex, SiO2, NH4NO3, NaCl, and custom-made core-shell particles) ablation and reproducibility of mass spectral signatures. We used a laser ablation aerosol time-of-flight single-particle mass spectrometer (LAAPTOF, AeroMegt GmbH), originally equipped with an excimer laser (wavelength 193 nm, pulse width 8 ns, pulse energy 4 mJ), and coupled it to an fs laser (Spectra Physics Solstice-100F ultrafast laser) with similar pulse energy but longer wavelengths (266 nm with 100 fs and 0.2 mJ, 800 nm with 100 fs and 3.2 mJ). We successfully coupled the free-firing fs laser with the single-particle mass spectrometer employing the fs laser light scattered by the particle to trigger mass spectra acquisition. Generally, mass spectra exhibit an increase in ion intensities (factor 1 to 5) with increasing laser power density (∼ 109 to ∼ 1013 W cm−2) from ns to fs laser. At the same time, fs-laser ablation produces spectra with larger ion fragments and ion clusters as well as clusters with oxygen, which does not render spectra interpretation more simple compared to ns-laser ablation. The idea that the higher power density of the fs laser leads to a more complete particle ablation and ionization could not be substantiated in this study. Quantification of ablated material remains difficult due to incomplete ionization of the particle. Furthermore, the fs-laser application still suffers from limitations in triggering it in a useful time frame. Further studies are needed to test potential advantages of fs- over ns-laser ablation in SPMS.

scholarly journals Improved identification of primary biological aerosol particles using single particle mass spectrometry

2016 ◽  
Author(s):  
Maria A. Zawadowicz ◽  
Karl D. Froyd ◽  
Daniel M. Murphy ◽  
Daniel J. Cziczo
Keyword(s):  
Mass Spectrometry ◽  
Single Particle ◽  
Mass Spectra ◽  
Aerosol Particles ◽  
Particle Mass ◽  
Cloud Formation ◽  
Single Particle Mass Spectrometry ◽  
Ambient Data ◽  
By Products ◽  
Biological Aerosol Particles

Abstract. Measurements of primary biological aerosol particles, especially at altitudes relevant to cloud formation, are scarce. Single particle mass spectrometry (SPMS) has been used to probe aerosol chemical composition from ground and aircraft for over 20 years. Here we develop a method for identifying bioaerosols using SPMS. We show that identification of bioaerosol using SPMS is complicated because phosphorus-bearing mineral dust and phosphorus-rich combustion by-products such as fly ash produce mass spectra with peaks similar to those typically used as markers for bioaerosol. We have developed a methodology to differentiate and identify bioaerosol using machine learning statistical techniques applied to mass spectra of known particle types. This improved method provides far fewer false positives compared to approaches reported in the literature. The new method was then applied to ambient data collected at Storm Peak Laboratory to show that 0.04–0.3 % of particles in the 200–3000 nm aerodynamic diameter range were identified as bioaerosol.

Expanding Single Particle Mass Spectrometer Analyses for the Identification of Microbe Signatures in Sea Spray Aerosol

2017 ◽  
Vol 89 (19) ◽  
pp. 10162-10170 ◽  
Author(s):  
Camille M. Sultana ◽  
Hashim Al-Mashat ◽  
Kimberly A. Prather
Keyword(s):  
Mass Spectrometer ◽  
Single Particle ◽  
Particle Mass ◽  
Sea Spray ◽  
Sea Spray Aerosol

scholarly journals Improved identification of primary biological aerosol particles using single-particle mass spectrometry

2017 ◽  
Vol 17 (11) ◽  
pp. 7193-7212 ◽  
Author(s):  
Maria A. Zawadowicz ◽  
Karl D. Froyd ◽  
Daniel M. Murphy ◽  
Daniel J. Cziczo
Keyword(s):  
Mass Spectrometry ◽  
Single Particle ◽  
Mass Spectra ◽  
Mineral Dust ◽  
Aerosol Particles ◽  
Central Valley ◽  
Particle Mass ◽  
Cloud Formation ◽  
Single Particle Mass Spectrometry ◽  
Biological Aerosol Particles

Abstract. Measurements of primary biological aerosol particles (PBAP), especially at altitudes relevant to cloud formation, are scarce. Single-particle mass spectrometry (SPMS) has been used to probe aerosol chemical composition from ground and aircraft for over 20 years. Here we develop a method for identifying bioaerosols (PBAP and particles containing fragments of PBAP as part of an internal mixture) using SPMS. We show that identification of bioaerosol using SPMS is complicated because phosphorus-bearing mineral dust and phosphorus-rich combustion by-products such as fly ash produce mass spectra with peaks similar to those typically used as markers for bioaerosol. We have developed a methodology to differentiate and identify bioaerosol using machine learning statistical techniques applied to mass spectra of known particle types. This improved method provides far fewer false positives compared to approaches reported in the literature. The new method was then applied to two sets of ambient data collected at Storm Peak Laboratory and a forested site in Central Valley, California to show that 0.04–2 % of particles in the 200–3000 nm aerodynamic diameter range were identified as bioaerosol. In addition, 36–56 % of particles identified as biological also contained spectral features consistent with mineral dust, suggesting internal dust–biological mixtures.

Exploring the Active Compounds of Traditional Mongolian Medicine Agsirga in Intervention of Novel Coronavirus (2019-nCoV) Based on HPLC-Q-Exactive-MS/MS and Molecular Docking Method

2020 ◽  
Author(s):  
Jie Cheng ◽  
Yuchen Tang ◽  
Baoquan Bao ◽  
Ping Zhang
Keyword(s):  
Mass Spectrometry ◽  
Molecular Docking ◽  
High Resolution ◽  
Mass Spectra ◽  
High Resolution Mass Spectrometry ◽  
Structural Formula ◽  
Active Compounds ◽  
High Resolution Mass ◽  
Q Exactive ◽  
Resolution Mass

<p><a></a><a></a><a></a><a><b>Objective</b></a>: To screen all compounds of Agsirga based on the HPLC-Q-Exactive high-resolution mass spectrometry and find potential inhibitors that can respond to 2019-nCoV from active compounds of Agsirga by molecular docking technology.</p> <p><b>Methods</b>: HPLC-Q-Exactive high-resolution mass spectrometry was adopted to identify the complex components of Mongolian medicine Agsirga, and separated by the high-resolution mass spectrometry Q-Exactive detector. Then the Orbitrap detector was used in tandem high-resolution mass spectrometry, and the related molecular and structural formula were found by using the chemsipider database and related literature, combined with precise molecular formulas (errors ≤ 5 × 10<sup>−6</sup>) , retention time, primary mass spectra, and secondary mass spectra information, The fragmentation regularities of mass spectra of these compounds were deduced. Taking ACE2 as the receptor and deduced compounds as the ligand, all of them were pretreated by discover studio, autodock and Chem3D. The molecular docking between the active ingredients and the target protein was studied by using AutoDock molecular docking software. The interaction between ligand and receptor is applied to provide a choice for screening anti-2019-nCoV drugs.</p> <p><b>Result</b>: Based on the fragmentation patterns of the reference compounds and consulting literature, a total of 96 major alkaloids and stilbenes were screened and identified in Agsirga by the HPLC-Q-Exactive-MS/MS method. Combining with molecular docking, a conclusion was got that there are potential active substances in Mongolian medicine Agsirga which can block the binding of ACE2 and 2019-nCoV at the molecular level.</p>

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