On-line single-particle analysis by laser desorption mass spectrometry

McKeown, Patrick J.; Johnston, Murray V.; Murphy, D. M.

doi:10.1021/ac00018a033

Cited by 152 publications

(95 citation statements)

References 25 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Another approach uses an aerodynamic particle time-of-flight to select the particle size range, followed by thermal vaporization and analysis using molecular mass spectrometry (Kolb et al, 2000). Other instruments perform single-particle composition analysis using mass spectrometry (McKeown et al, 1991;Carson et al, 1995;Marijinissen et al, 1988;Liu et al, 1999;Middlebrook et al, 2001;Prather et al, 1994). Single particle mass spectrometry measurements are generally not quantitative, although they provide valuable single-particle composition information.…”

Section: Introductionmentioning

confidence: 99%

Semi-continuous PM2.5 inorganic composition measurements during the Pittsburgh Air Quality Study

Wittig

Takahama

Khlystov

et al. 2004

Atmospheric Environment

View full text Add to dashboard Cite

A method for semi-continuous (10 min time resolution) PM 2.5 nitrate and sulfate measurements, based on the humidified impaction with flash volatilization design of Stolzenburg and Hering (Environ. Sci. Technol. 34 (2000) 907), was evaluated during the Pittsburgh Air Quality Study (PAQS) from July 2001 to August 2002. The semi-continuous measurements were corrected for several operating parameters. The overall corrections were less than 10% on average, but could be quite large for individual 10 min measurements. These corrections resulted in an improvement in the agreement of the measurements with the filter-based measurements, with a major axis regression relationship of y ¼ 0:83x þ 0:20 mg m À3 and R 2 of 0.84 for nitrate and y ¼ 0:71x þ 0:42 mg m À3 and R 2 of 0.83 for sulfate. The corrected semi-continuous measurements were calibrated over the entire year using collocated denuder/filterpack-based measurements. These calibrated semi-continuous measurements are used in conjunction with temporally resolved gas-phase measurements of total (gas-and aerosol-phase) nitrate and meteorological measurements to investigate short-term phenomena at the Pittsburgh Supersite. The gas-to-particle partitioning of nitrate varied daily and seasonally, with a majority of the nitrate in the particle phase at night and during the winter months. r

show abstract

Section: Introductionmentioning

confidence: 99%

Semi-continuous PM2.5 inorganic composition measurements during the Pittsburgh Air Quality Study

Wittig

Takahama

Khlystov

et al. 2004

Atmospheric Environment

View full text Add to dashboard Cite

show abstract

“…Similar to LAMMS, single particle mass spectrometers also ablate and ionize particles with high-energy laser pulses, but particles are suspended in the center of the source region and analyzed less than a millisecond after entering the vacuum [7].…”

mentioning

confidence: 99%

Ion formation mechanism in laser desorption ionization of individual nanoparticles

Reinard

Johnston

2008

J. Am. Soc. Mass Spectrom.

View full text Add to dashboard Cite

Covariance mapping is used to study ion formation mechanisms in laser desorption ionization of individual 50 or 220 nm diameter particles having compositions similar to ambient aerosol. Single particle mass spectra are found to vary substantially from particle to particle. This variation is systematic-the energetically preferred ions (e.g., lowest ionization energy, highest electron affinity) are positively correlated with each other and negatively correlated with less preferred ions. For the compositions studied, the average positive ion yield is two to five times greater than the negative ion yield, indicating that free electrons are the main negatively charged species. For many particles, typically 20% to 40% of those analyzed, only positive ions are detected. Smaller particles give fewer negative ions, presumably because the plume is less dense and electron capture is less likely. The results suggest that ion formation occurs by a two stage process. In the first stage, photoionization of laser desorbed neutrals gives cations and free electrons. In the second stage, collisions in the plume cause electron capture and competitive charge transfer. When the particle ablates in a manner giving a dense plume with many collisions, the energetically preferred positive and negative ions are dominant. When the particle ablates in a manner giving a less dense plume with fewer collisions, the less preferred ions are able to survive and the energetically preferred ions constitute a lower fraction of the total ion signal. Systematic particle to particle variations of relative signal intensities can complicate ambient particle classification efforts by spreading a single particle composition over several classes. . In our laboratory, RSMS uses a single 193 nm laser pulse to ablate and ionize material from the particle [4]. Intense ion signals can be obtained from most particle compositions: refractory and semivolatile, organic and inorganic. A common feature of this and other laser desorption ionization sequences is that the ionization mechanism is not fully understood [2].The LDI mass spectra from single particle mass spectrometers are similar to those obtained with laser microprobe mass spectrometry (LAMMS), a decades old method capable of analyzing particles and bulk materials deposited on a substrate [5,6]. Similar to LAMMS, single particle mass spectrometers also ablate and ionize particles with high-energy laser pulses, but particles are suspended in the center of the source region and analyzed less than a millisecond after entering the vacuum [7].Some effort has been made to elucidate the mechanisms of LDI in single particle mass spectrometry. Measurements of the kinetic energy distribution of ions formed by LDI has provided some information regarding the physical processes that occur during ionization [8,9]. Computational models have characterized the disintegration of particles irradiated with a short laser pulse [10 -12]. Most studies of the ion formation mechanism in LDI, though, have been performed on solids and...

show abstract

“…In this first apparatus, full spectra could not be acquired from single particles due to the use of a quadrupole mass spectrometer, and only monodisperse aerosols could be efficiency analyzed. In 1988, Marijnissen et al proposed the use of a time-of-flight mass spectrometer (TOFMS) [8], but McKeown et al in 1991 were the first to build and describe an on-line system [9]. Prather et al added aerodynamic sizing to a TOFMS to enable the accurate sizing and efficient analysis of polydisperse aerosols in 1994 [10].…”

mentioning

confidence: 99%

Parameters contributing to efficient ion generation in aerosol MALDI mass spectrometry

McJimpsey

Jackson

Lebrilla

et al. 2008

J. Am. Soc. Mass Spectrom.

View full text Add to dashboard Cite

The Bioaerosol Mass Spectrometry (BAMS) system was developed for the real-time detection and identification of biological aerosols using laser desorption ionization. Greater differentiation of particle types is desired; consequently MALDI techniques are being investigated. The small sample size (ϳ1 m 3 ), lack of substrate, and ability to simultaneously monitor both positive and negative ions provide a unique opportunity to gain new insight into the MALDI process. Several parameters known to influence MALDI molecular ion yield and formation are investigated here in the single particle phase. A comparative study of five matrices (2,6-dihydroxyacetophenone, 2,5-dihydroxybenzoic acid, ␣-cyano-4-hydroxycinnamic acid, ferulic ␣ acid, and sinapinic acid) with a single analyte (angiotensin I) is presented and reveals effects of matrix selection, matrix-to-analyte molar ratio, and aerosol particle diameter. The strongest analyte ion signal is found at a matrix-to-analyte molar ratio of 100:1. At this ratio, the matrices yielding the least and greatest analyte molecular ion formation are ferulic acid and ␣-cyano-␣ 4-hydroxycinnamic acid, respectively. Additionally, a significant positive correlation is found between aerodynamic particle diameter and analyte molecular ion yield for all matrices. SEM imaging of select aerosol particle types reveals interesting surface morphology and structure.

show abstract

On-line single-particle analysis by laser desorption mass spectrometry

Cited by 152 publications

References 25 publications

Semi-continuous PM2.5 inorganic composition measurements during the Pittsburgh Air Quality Study

Semi-continuous PM2.5 inorganic composition measurements during the Pittsburgh Air Quality Study

Ion formation mechanism in laser desorption ionization of individual nanoparticles

Parameters contributing to efficient ion generation in aerosol MALDI mass spectrometry

Contact Info

Product

Resources

About