Coincidence in Time-of-Flight Aerosol Spectrometers: Phantom Particle Creation

Heitbrink, William A.; Baron, Paul A.; Willeke, Klaus

doi:10.1080/02786829108959476

Cited by 42 publications

(29 citation statements)

References 5 publications

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“…This was the case for size channels with average or high number of spore counts; but not for size channels with low spore counts ( Table 2). This could be explained as resulting from the influence of particle coincidence (phantom) (Heitbrink and Baron, 1991;Holm et al, 1997) and the slower recovery of the UV laser compared to the recovery of the APS laser of the UVAPS (Agranovski et al, 2003a), which leads to lower estimates of the real fluorescent percentage. The effect of the last phenomenon was obvious when the fluorescent particle number was low i.e.…”

Section: The Effect Of Age On Fungal Spore Fluorescent Percentagementioning

confidence: 99%

Performance assessment of UVAPS: Influence of fungal spore age and air exposure

Kanaani

Hargreaves

Ristovski

et al. 2007

Journal of Aerosol Science

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This work focused on two main outcomes. The first was the assessment of the response of the Ultraviolet Aerodynamic Particle Sizer Spectrometer (UVAPS) for two different fungal spore species.The UVAPS response was investigated as a function of fungal age and the frequency of air current that their colonies exposure to. This outcome was achieved through the measurement of fungal spore fluorescent percentage and fluorescent intensity throughout a period of culturing time (three weeks), and the study of their fluorescent percentage as a function of exposure to air currents. The second objective was to investigate the change of fungal spore size during this period, which may be of use as a co-factor in this differentiation. Fungal spores were released by blowing the surface of the culture colonies with continuous filtered flow air. The UVAPS was used to detect and measure autofluorescing biomolecules such as riboflavin and nicotinamide adenine dinucleotide phosphate (NAD(P)H) present in the released fungal spores.The study demonstrated an increase in aerodynamic diameter for fungal spores under investigation (Aspergillus niger and Penicillium species) over a period of time. The fluorescent percentage of spores was found to decrease for both fungal genera as they aged. It was also found that the fluorescent percentage for tested fungi decreased with frequency of air exposure. The results showed that, while the UVAPS could discriminate between Aspergillus and Penicillium species under well-controlled laboratory conditions, it is unlikely to be able to do so in the field.

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Section: The Effect Of Age On Fungal Spore Fluorescent Percentagementioning

confidence: 99%

Performance assessment of UVAPS: Influence of fungal spore age and air exposure

Kanaani

Hargreaves

Ristovski

et al. 2007

Journal of Aerosol Science

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“…Using the TSI software, the APS data were corrected for coincidence, which occurs when particles are erroneously counted by the detector of the instrument (Heitbrink and Baron 1991;Heitbrink and Baron 1992;TSI 1993;TSI 1995). Particle number concentrations were converted to mass concentrations using the density of the particles (see Table 1).…”

Section: Determination Of Mass Concentrationsmentioning

confidence: 99%

Evaluation of the Measurement Performance of the Scanning Mobility Particle Sizer and Aerodynamic Particle Sizer

Sioutas¹

1999

Aerosol Science and Technology

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Findings from the monodisperse aerosol tests indicate that the mass concentrations obtained by the APS compared similarly to those obtained using the gravimetric method for particle sizes between 0.5-9.2 m m. Similarly, SMPS measurements were in good agreement with the gravimetric analysis for particle sizes between 0.3-0.5 m m. However, for particles less than 0.30 m m, the SMPS overestimated their mass concentrations by a factor of 1.5-1.6. Tests using polydisperse aerosols showed that at particle size ranges from 0.09-0.18 m m and from 0.18-0.29 m m, the SMPS also overestimated mass concentrations.

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“…The ability of the APS in making accurate mass-weighted size distribution measurements was improved over the past decade. In fact the old APS 3320, used in Shen et al (2002), featuring double-crest optics and improved signal processing, eliminated the effect of false counts due to coincidence and phantom particles measured in the previous 3300 and 3310 APS Models (Heitbrink et al 1991) providing better distribution measurements of more concentrated aerosols. However, the accuracy in calculating mass distribution was still limited by a very low-level background of false, large-particle counts revealed when the effect of the coincidence and phantom particles was eliminated.…”

mentioning

confidence: 99%

Uncertainty Budget of the SMPS–APS System in the Measurement of PM₁, PM_2.5, and PM₁₀

Buonanno

Dell’Isola

Stabile

et al. 2009

Aerosol Science and Technology

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The effects of particulate matter on environment and public health have been widely studied in recent years. In spite of the presence of numerous studies about this topic there is no agreement on the relative importance of the particles' size and origin with respect to health effects among researchers. Nevertheless, air quality standards are moving, as the epidemiological attention, towards greater focus on the smaller particles. The most reliable method used in measuring particulate matter (PM) is the gravimetric method since it directly measures PM concentration, guaranteeing an effective traceability to international standards. This technique, however, neglects the possibility to correlate short term intraday atmospheric parameter variations that can influence ambient particle concentration and size distribution as well as human activity patterns. Besides, a continuous method to determine PM concentrations through the measurement of the number size distribution is the system constituted by a Scanning Mobility Particle Sizer (SMPS) and an Aerodynamic Particle Sizer (APS). In this article, the evaluation of the uncertainty budget in measuring PM through the SMPS-APS system, as well as a metrological comparison with the gravimetric reference method in order to analyze the compatibility, was carried out and applied with reference to an experimental campaign developed in a rural site. This choice allowed to assume the hypothesis of spherical particle morphology. The average PM 10 , PM 2.5 , and PM 1 uncertainties obtained for the SMPS-APS system are equal to 27%, 29%, and 31%, respectively. Here the principle influence parameter is the particle density that has to be directly measured with low uncertainty in order to reduce the PM uncertainty.

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Coincidence in Time-of-Flight Aerosol Spectrometers: Phantom Particle Creation

Cited by 42 publications

References 5 publications

Performance assessment of UVAPS: Influence of fungal spore age and air exposure

Performance assessment of UVAPS: Influence of fungal spore age and air exposure

Evaluation of the Measurement Performance of the Scanning Mobility Particle Sizer and Aerodynamic Particle Sizer

Uncertainty Budget of the SMPS–APS System in the Measurement of PM₁, PM_2.5, and PM₁₀

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Coincidence in Time-of-Flight Aerosol Spectrometers: Phantom Particle Creation

Cited by 42 publications

References 5 publications

Performance assessment of UVAPS: Influence of fungal spore age and air exposure

Performance assessment of UVAPS: Influence of fungal spore age and air exposure

Evaluation of the Measurement Performance of the Scanning Mobility Particle Sizer and Aerodynamic Particle Sizer

Uncertainty Budget of the SMPS–APS System in the Measurement of PM1, PM2.5, and PM10

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Uncertainty Budget of the SMPS–APS System in the Measurement of PM₁, PM_2.5, and PM₁₀