Paper spray mass spectrometry for the analysis of picoliter droplets

Kohli, Ravleen Kaur; Davies, James F.

doi:10.1039/c9an02534k

Cited by 9 publications

(30 citation statements)

References 54 publications

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“…Two complementary ionization sources are used in these experiments: paper spray ionization 50,54,55 and thermal desorption coupled to helium glow discharge ionization. 50,56 Development and use of these ion sources for detection of single micron-sized droplets is described in detail in Jacbos et al, 51 Kohli & Davies 54,55 and Willis et al 50 Their operation is summarized below.…”

Section: Single Droplet Ambient Ionization Mass Spectrometry All Meas...mentioning

confidence: 99%

Coupled interfacial and bulk kinetics govern the timescales of multiphase ozonolysis reactions

Willis

Wilson

2022

Preprint

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Chemical transformations in aerosol impact the lifetime of particle-phase species, the fate of atmospheric pollutants, and both climate and health-relevant aerosol properties. Timescales for multiphase reactions of ozone in atmospheric aqueous phases are governed by coupled kinetic processes between the gas-phase, the particle interface and its bulk, which respond dynamically to reactive consumption of O3. However, models of atmospheric aerosol reactivity often do not account for the coupled nature of multiphase processes. To examine these dynamics, we use new and prior experimental observations of aqueous droplet reaction kinetics, including three systems with a range of surface affinities and ozonolysis rate coefficients (trans-aconitic acid (C6H6O6), maleic acid (C4H4O4) and sodium nitrite (NaNO2)). Using literature rate coefficients and thermodynamic properties, we constrain a simple two-compartment stochastic kinetic model, which resolves the interface from the particle bulk and represents O3 partitioning, diffusion and reaction as a coupled kinetic system. Our kinetic model accurately predicts decay kinetics across all three systems, demonstrating that both the thermodynamic properties of O3 and the coupled kinetic and diffusion processes are key to making accurate predictions. An enhanced concentration of adsorbed O3, compared to gas and bulk phases, is rapidly maintained and remains constant even as O3 is consumed by reaction. Multiphase systems dynamically seek to achieve equilibrium in response to reactive O3 loss, but this is hampered at solute concentrations relevant to aqueous aerosol by the rate of O3 arrival in the bulk by diffusion. As a result, bulk-phase O3 becomes depleted from its Henry’s Law solubility. This bulk-phase O3 depletion limits reaction timescales for relatively slow-reacting organic solutes with low interfacial affinity (i.e., trans-aconitic and maleic acids, with krxn ~ 10^3 - 104 M-1 s-1), which is in contrast to fast-reacting solutes with higher surface affinity (i.e., nitrite, with krxn ~ 10^5 M-1 s-1) where surface reactions strongly impact observed decay kinetics.

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Section: Single Droplet Ambient Ionization Mass Spectrometry All Meas...mentioning

confidence: 99%

Coupled interfacial and bulk kinetics govern the timescales of multiphase ozonolysis reactions

Willis

Wilson

2022

Preprint

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“…Impact of solvent and spray tip position on single droplet detection PS-MS specific considerations for reproducibility are spray stability and droplet deposition location 37 . Negative ion mode PS-MS has intrinsic challenges related to the high current involved, and addition of CHCl 3 to the spray solvent has been shown to mitigate the formation of corona discharges from fibres at the spray tip 44,55 .…”

Section: Detection Of Single Aqueous Dropletsmentioning

confidence: 99%

“…With negative ion mode PS-MS, positively charged single droplets are ejected from the QET and are attracted toward the spray tip. The deposition location of droplets on the paper substrate impacts both the single droplet event timescale and reproducibility, as described for free-falling neutral droplets by Kaur Kohli and Davies 37 . We observe good reproducibility in droplet signals with the spray tip positioned in line with the edge of the QET outlet, such that droplets likely land slightly behind the spray tip 37 .…”

Section: Detection Of Single Aqueous Dropletsmentioning

confidence: 99%

“…However, experimental challenges arise with this approach when applied to water droplets because of their higher surface tension than methanol. Aqueous droplets, free-falling onto a paper substrate, have been quantitatively analyzed with paper spray ionization MS 37 .…”

mentioning

confidence: 99%

“…However, experimental challenges arise with this approach when applied to water droplets because of their higher surface tension than methanol. Aqueous droplets free-falling onto a paper substrate have been quantitatively analyzed with paper spray ionization MS (PS-MS) . This work demonstrated the quantitative capabilities of paper spray for droplets containing a range of analytes, with limits of detection for citric acid on the order of 0.5 pg.…”

mentioning

confidence: 99%

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Combining Mass Spectrometry of Picoliter Samples with a Multicompartment Electrodynamic Trap for Probing the Chemistry of Droplet Arrays

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Single droplet levitation provides contactless access to the microphysical and chemical properties of micron-sized samples. Most applications of droplet levitation to chemical and biological systems use non-destructive optical techniques to probe droplet properties. To provide improved chemical specificity, we couple a multi-compartment quadrupole electrodynamic trap (QET) to single droplet mass spectrometry. Our QET continuously traps a monodisperse droplet population (∼10's -100's of droplets), and allows for simultaneous sizing of a single droplet using its Mie scattering pattern. Single droplets are subsequently ejected to the ionization region of an ambient pressure inlet mass spectrometer. We optimize two complementary soft ionization techniques for picoliter aqueous droplets: paper spray (PS) ionization and thermal desorption glow discharge (TDGD) ionization. Both techniques detect oxygenated organic acids in single droplets with signal-to-noise ratios >100 and detection limits on the order of

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Recent advances in mass spectrometry techniques for atmospheric chemistry research on molecular‐level

Wen

Zhang

2023

Mass Spectrometry Reviews

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The Earth's atmosphere is composed of an enormous variety of chemical species associated with trace gases and aerosol particles whose composition and chemistry have critical impacts on the Earth's climate, air quality, and human health. Mass spectrometry analysis as a powerful and popular analytical technique has been widely developed and applied in atmospheric chemistry for decades. Mass spectrometry allows for effective detection, identification, and quantification of a broad range of organic and inorganic chemical species with high sensitivity and resolution. In this review, we summarize recently developed mass spectrometry techniques, methods, and applications in atmospheric chemistry research in the past several years on molecular‐level. Specifically, new developments of ion‐molecule reactors, various soft ionization methods, and unique coupling with separation techniques are highlighted. The new mass spectrometry applications in laboratory studies and field measurements focused on improving the detection limits for traditional and emerging volatile organic compounds, characterizing multiphase highly oxygenated molecules, and monitoring particle bulk and surface compositions.

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Paper spray mass spectrometry for the analysis of picoliter droplets

Abstract: Paper spray ionization coupled with high resolution mass spectrometry is shown to be an effective strategy for the analysis of picoliter droplets containing atmospherically-relevant oxygenated organic compounds.

Cited by 9 publications

References 54 publications

Coupled interfacial and bulk kinetics govern the timescales of multiphase ozonolysis reactions

Coupled interfacial and bulk kinetics govern the timescales of multiphase ozonolysis reactions

Combining Mass Spectrometry of Picoliter Samples with a Multicompartment Electrodynamic Trap for Probing the Chemistry of Droplet Arrays

Recent advances in mass spectrometry techniques for atmospheric chemistry research on molecular‐level

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