Aerosol Mass Spectrometer for Simultaneous Detection of Polyaromatic Hydrocarbons and Inorganic Components from Individual Particles

Passig, Johannes; Schade, Julian; Oster, Markus; Fuchs, Matthias; Ehlert, Sven; Jäger, Cornelia; Sklorz, Martin; Zimmermann, Ralf

doi:10.1021/acs.analchem.7b01207

Cited by 32 publications

(20 citation statements)

References 36 publications

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“…PALMS and other SPMS instruments that use single-step laser desorption-ionization (LDI) are not inherently quantitative because ion formation is not a well-controlled process and gives rise to 15 considerable particle-to-particle variability in both total and relative ion signals (Hinz and Spengler, 2007;Murphy, 2007). Many bulk aerosol mass spectrometers (Canagaratna et al, 2007;Tobias et al, 2000) and some SPMS instruments (Passig et al, 2017;Simpson et al, 2009;Sykes et al, 2002) use a two-step particle desorption and ionization process that can more readily quantify particle sub-components. Very high laser irradiances generate plasmas that can also improve consistency in ion signals but at the expense of losing all molecular information (Wang and Johnston, 2006).…”

Section: Introductionmentioning

confidence: 99%

A new method to quantify mineral dust and other aerosol species from aircraft platforms using single particle mass spectrometry

Froyd¹,

Murphy²,

Brock³

et al. 2019

Preprint

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Abstract. Single-particle mass spectrometer (SPMS) instruments characterize the composition of individual aerosol particles in real time. Their fundamental ability to differentiate the externally mixed particle types that constitute the atmospheric aerosol population enables a unique perspective into sources and transformation. However, quantitative measurements by SPMS systems are inherently problematic. We introduce a new technique that combines collocated measurements of aerosol composition by SPMS and size-resolved absolute particle concentrations on aircraft platforms. Quantitative number, surface area, volume, and mass concentrations are derived for climate-relevant particle types such as mineral dust, sea salt, and biomass burning smoke. Additionally, relative ion signals are calibrated to derive mass concentrations of internally mixed sulfate and organic material that are distributed across multiple particle types. The NOAA Particle Analysis by Laser Mass Spectrometry (PALMS) instrument measures size-resolved aerosol chemical composition from aircraft. We describe the identification and quantification of nine major atmospheric particle classes, including sulfate/organic/nitrate mixtures, biomass burning, elemental carbon, sea salt, mineral dust, meteoric material, alkali salts, heavy fuel oil combustion, and a remainder class. Classes can be sub-divided as necessary based on chemical heterogeneity, accumulated secondary material during aging, or other atmospheric processing. Concentrations are derived for sizes that encompass the accumulation and coarse size modes. A statistical error analysis indicates that particle class concentrations can be determined within a few minutes for abundances above ~ 10 ng m−3. Rare particle types require longer sampling times. We explore the instrumentation requirements and the limitations of the method for airborne measurements. Reducing the size resolution of the particle data increases time resolution with only a modest increase in uncertainty. The principal limiting factor to fast time response concentration measurements is statistically relevant sampling across the size range of interest, in particular, sizes D 2 μm for coarse mode analysis. We demonstrate the use of a virtual impactor to enhance sampling statistics for the inherently sparse coarse mode. Performance is compared to other airborne and ground-based composition measurements, and examples of atmospheric mineral dust concentrations are given. The wealth of information afforded by composition-resolved size distributions for all major aerosol types represents a new and powerful tool to characterize atmospheric aerosol properties in a quantitative fashion.

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Section: Introductionmentioning

confidence: 99%

A new method to quantify mineral dust and other aerosol species from aircraft platforms using single particle mass spectrometry

Froyd¹,

Murphy²,

Brock³

et al. 2019

Preprint

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“…For online gas phase REMPI-MS measurements [24][25][26] or direct REMPI-MS analysis of liquid samples with either membrane inlet [27][28][29] or direct inlet techniques [30], a native or isotope labeled internal standard (e.g., toluene or D3-toluene) can be added to semi-quantify the polycyclic aromatic compounds via relPICS. Additionally, for REMPI-based analytical techniques, which do not allow a straight forward internal standardization approach, such as laser desorption REMPI-MS online analysis of PAHs on a single aerosol particle [31], the relPICS allow the determination of the pattern of the aromatic compounds.…”

Section: Introductionmentioning

confidence: 99%

Determination of Relative Ionization Cross Sections for Resonance Enhanced Multiphoton Ionization of Polycyclic Aromatic Hydrocarbons

et al. 2018

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Resonance enhanced multiphoton ionization (REMPI) is a powerful method for the sensitive determination of polycyclic aromatic hydrocarbons (PAHs) in gaseous mixtures via mass spectrometry (MS). In REMPI, ions are produced by the absorption of at least two photons including defined electronic intermediate states. As a result—unlike other laser-based ionization techniques—spectroscopic selectivity is involved into the ionization process. Nevertheless, these wavelength-dependent ionization rates impede the quantification using REMPI. For this purpose, relative photoionization cross sections (relPICS) give an easy-to-use approach to quantify REMPI-MS measurements. Hereby, the ionization behavior of a single compound was compared to that of a reference substance of a given concentration. In this study, relPICS of selected single-core aromatics and PAHs at wavelengths of 266 nm and 248 nm were determined using two different time-of-flight mass spectrometric systems (TOFMS). For PAHs, relPICS were obtained which showed a strong dependence on the applied laser intensity. In contrast, for single-core aromatics, constant values of relPICS were determined. Deviations of relPICS between both TOFMS systems were found for small aromatics (e.g., benzene), which can be assigned to the differences in UV generation in the particular system. However, the relPICS of this study were found to be in good agreement with previous results and can be used for system-independent quantification.

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“…Although a two-step approach separating laser ablation and laser ionization bears several advantages for identifying specific molecules (Passig et al, 2017) many instruments currently still use single-step laser desorption and ionization. Single-particle mass spectrometers currently in use by different groups worldwide have very similar designs (Gaie-Levrel et al, 2012;Johnston, 2000;Murphy and Thomson, 1995;Zelenyuk et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

Exploring femtosecond laser ablation in single-particle aerosol mass spectrometry

et al. 2018

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Abstract. Size, composition, and mixing state of individual aerosol particles can be analysed in real time using singleparticle 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 (10 7 -10 10 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, SiO 2 , NH 4 NO 3 , 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 freefiring 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 (∼ 10 9 to ∼ 10 13 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 fslaser 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.

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Aerosol Mass Spectrometer for Simultaneous Detection of Polyaromatic Hydrocarbons and Inorganic Components from Individual Particles

Cited by 32 publications

References 36 publications

A new method to quantify mineral dust and other aerosol species from aircraft platforms using single particle mass spectrometry

A new method to quantify mineral dust and other aerosol species from aircraft platforms using single particle mass spectrometry

Determination of Relative Ionization Cross Sections for Resonance Enhanced Multiphoton Ionization of Polycyclic Aromatic Hydrocarbons

Exploring femtosecond laser ablation in single-particle aerosol mass spectrometry

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