Christopher A. Noble

Real-time single particle mass spectrometry: a historical review of a quarter century of the chemical analysis of aerosols

Real-time single particle mass spectrometry, or continuous aerosol mass spectrometry, was originally developed in the 1970s for the purpose of identifying the chemical composition of airborne particulate matter in real-time. Although this technique has continued to evolve throughout the following decades, the fundamental characteristic of this method remains the same, involving the continuous introduction of solid particle or liquid droplets directly into the ion source region of a mass spectrometer. Continuous sample introduction allows for the chemical analysis of single airborne particles in real-time. A number of mass analyzers have been employed in real-time single particle mass spectrometry. The original real-time single particle mass spectrometer used a magnetic sector mass analyzer. Quadrupole, double-focusing, and ion trap mass spectrometers have also been utilized. The majority of the current real-time single particle mass spectrometry techniques use time-of-flight mass spectrometry. In the literature, a variety of general names have been applied to real-time single particle mass spectrometry methods. These names include direct-inlet mass spectrometry, on-line laser microprobe mass spectrometry, particle analysis by mass spectrometry, particle beam mass spectrometry, and rapid-single particle mass spectrometry. This review covers real-time single particle mass spectrometry techniques that were developed from 1973 through 1998, specifically for analyzing airborne particulate matter, including environmental aerosols, biological aerosols, and clean-room aerosols. Because the majority of the historical and current real-time single particle mass spectrometers have been employed for atmospheric aerosols, this topic is the primary focus of this review. This review does not include on-line mass spectrometry methods that are employed as a detector for other instrumental methods, such as liquid chromatography.

Aerodynamic Particle Sizing versus Light Scattering Intensity Measurement as Methods for Real-Time Particle Sizing Coupled with Time-of-Flight Mass Spectrometry.

Measurement of scattered light intensity and aerodynamic particle sizing are two methods that have recently been coupled with time-of-flight mass spectrometry for real-time determination of aerosol particle size and composition. An aerosol analysis technique recently developed in our laboratory, aerosol time-of-flight mass spectrometry, offers a unique experimental platform to evaluate both of these sizing techniques. This paper presents a comparison of results obtained with these two methods.

Aerosol characterization using mass spectrometry

Abstract Mass spectrometry serves as a particularly useful technique in the analysis of environmental samples. Recent advances in aerosol characterization techniques now allow for in situ particle analysis in real time, determining both particle size and chemical composition simultaneously for single particles.

Single Particle Characterization of Albuterol Metered Dose Inhaler Aerosol in Near Real-Time

ABSTRACT Metered dose inhalers produce a fine spray of aerosol particles that are used as an inhalation drug delivery system for a variety of therapeutic purposes. Common analytical methods employed for characterizing the aerosol dosage are typically off-line analyses for both chemical information and particle size distributions, and focus on the bulk aerosol rather than on single particles. Aerosol time-of-flight mass spectrometry offers the capability to analyze the aerosol dose in near real-time, providing both size and chemical information for single particles. Though aerosol time-of-flight mass spectrometry has been used primarily to characterize environmental samples, this is the first demonstration of its bioanalytical capabilities. This paper discusses the characterization of an albuterol metered dose inhaler using both high and low laser power for the desorption/ionization process in order to control the amount of fragmentation observed in the mass spectral analysis. Using high laser power, signi...

Real‐time single particle monitoring of a relative increase in marine aerosol concentration during winter rainstorms

During the months of December 1996 and January 1997, aerosol characterization was performed in real-time at Riverside, CA, an inland location approximately 100 km east of the Los Angeles coast. Analysis was performed on a single particle basis with measurements of both particle size and composition. Data were collected throughout the course of five rainstorms. Single particle mass spectra demonstrate that obvious composition changes occur in the aerosol systems as the marine air mass is transported inland. While precipitation scavenging of aerosols was observed, there was a significant relative increase of sea salt particles in the non-scavenged aerosol. Compositionally-resolved particle size distributions also demonstrate real-time changes that occur in the atmospheric aerosol sample.

AIR POLLUTION: THE ROLE OF PARTICLES

Although air pollution may seem like a modern concern, governments have been dealing with it since the late 13th century, when a commission was set up to investigate the problem in London. Legislation to regulate pollution sources first appeared in England early in the following century. Indeed, a repeat offender of this law is thought to have been tortured and executed in 1307.

Aerosol Time-of-Flight Mass Spectrometry: A New Method for Performing Real-Time Characterization of Aerosol Particles

Abstract Recently our research group has developed aerosol time-of-flight mass spectrometry, an instrumental method for the real-time characterization of individual aerosol particles. Aerosol time-of-flight mass spectrometry couples two-laser aerodynamic particle sizing with time-of-flight mass spectrometry to measure both the size and composition of single particles. One of the aims of this research is to provide more detailed measurements of atmospheric aerosol particles than are currently available for epidemiological studies. Current aerosol data mainly consist of particle mass concentration measurements, which are employed to correlate particle concentration with effects on mortality and morbidity. Sample spectra of several different particle classifications are shown. Monitoring ambient aerosols over time demonstrates that significant changes in particle chemical composition can occur without correspondingly large changes in the total size distribution. Also, certain metal species (such as iron, lea...