Online Nanoparticle Mass Measurement by Combined Aerosol Particle Mass Analyzer and Differential Mobility Analyzer: Comparison of Theory and Measurements

Abstract

A combination of a differential mobility analyzer (DMA) and aerosol particle mass analyzer (APM) is used to measure the mass of NIST Standard Reference Materials (SRM R ) PSL spheres with 60 and 100 nm nominal diameter, and NIST traceable 300 nm PSL spheres. The calibration PSL spheres were previously characterized by modal diameter and spread in particle size. We used the DMA to separate the particles with modal diameter in a narrow mobility diameter range. The mass of the separated particles is measured using the APM. The measured mass is converted to diameter using a specific density of 1.05. We found that there was good agreement between our measurements and calibration modal diameter. The measured average modal diameters are 59.23 and 101.2 nm for nominal diameters of 60 and 100 nm (calibration modal diameter: 60.39 and 100.7 nm) PSL spheres, respectively. The repeatability uncertainty of these measurements is reported. For 300 nm, the measured diameter was 305.5 nm, which is an agreement with calibration diameter within 1.8%.The effect of spread in particle size on the APM transfer function is investigated. Two sources of the spread in "mono-dispersed" particle size distributions are discussed: (a) spread due to the triangular DMA transfer function, and (b) spread in the calibration particle size. The APM response function is calculated numerically with parabolic flow through the APM and diffusion broadening. As expected from theory, the calculated APM response function and measured data followed a similar trend with respect to APM voltage. However, the theoretical APM transfer function is narrower than the measured APM response.

Electrospray–differential mobility analysis of bionanoparticles

“…Gold nanoparticles (Ted Pella) prepared in ammonium acetate buffer or 60 nm polystyrene latex particles (NIST SRM ® 1963) were used as system suitability standards to confirm operation of the instrumentation [15,78,143].…”

“…It can be easily hyphenated with DMAs to measure mass of particles preselected by the DMA as has been demonstrated before [78]. In principle, depending on the resolution of the APM it can also be used to measure the mass of ligand adsorbed to nanoparticles and thus eliminates the shortcoming of the ES-DMA that may arise because of configuration changes in the protein.…”

“…A more detailed study of the lower limit of ES-DMA will also be provided in chapter 7 (in context of viruses) and chapter 8 (in context of proteins). b) The uncertainty in measurements of ES-DMA is typically ± 0.3 nm from a size range of a few nanometers to at least ~ 100 nm [75] and appears to be independent of resolution [78]. However, this uncertainty sometimes may not be adequate to distinguish proteins with slight differences in molecular weight.…”

Design Considerations and Performance Evaluation of a Compact Aerosol Particle Mass Analyzer

“…When the number of charges on a particle is known, the APM can determine the particle mass. The APM has been used, often in combination with a differential mobility analyzer (DMA), for evaluation of various particle properties such as "effective" density (McMurry et al 2002;Geller et al 2006;Malloy et al 2009;Liu et al 2012), morphology through estimation of the mass-mobility exponent (Park et al 2003a; Ku et al 2006;Kim et al 2009;Nakao et al 2011;Scheckman and McMurry 2011;Torvela et al 2011;Eggersdorfer et al 2012;Guha et al 2012;Ku and Evans 2012), the mixing ratio of internally-mixed particles (Sakurai et al 2003;Park et al 2008;Khalizov et al 2009;Ma and Zachariah 2009), material density (Park et al 2004;Kuwata et al 2012), particulate mass concentration (Park et al 2003b;Saito et al 2008), mass (Kuwata et al 2009;Lall et al 2009), volume (Lall et al 2008), and porosity (Lee et al 2011). The APM can also be used as a generator of particles having a specified mass (Malik et al 2011;Moteki et al 2011;Laborde et al 2012;Beranek et al 2012).…”

The Nano-Particle Mass Classifier (Nano-PMC): Development, Characterization, and Application for Determining the Mass, Apparent Density, and Shape of Particles with Masses Down to the Zeptogram Range

“…Diffusion is described in the model with a stochastic algorithm, analogous to that used for the original APM design (Hagwood et al 1995;Lall et al 2009). …”