Measuring air borne nanoparticles for characterizing hyphenated RDD-SMPS-ICPMS instrumentation

Scanning Mobility Particle Sizer (SMPS) and Inductively Coupled Plasma Mass Spectrometry (ICPMS), complemented by a Rotating Disk Diluter (RDD) to a hyphenated RDD-SMPS-ICPMS measuring setup, allow online and simultaneous determination of size distribution and elemental composition of gas borne nanoparticles. This coupling strategy offers high flexibility in terms of dealing with different aerosols, loaded with metallic nanoparticles. The capabilities of such an instrument are demonstrated on uniformly composited metal aerosols, as well as an aerosol mixture containing smaller gold and larger silver nanoparticles. The size resolved ICPMS intensity curves correlate very well to the size distributions, determined by the coupled SMPS, and also to those from a non-modified reference SMPS instrument. Particulate iron, gold, and silver are detected with SMPS scan durations of a few minutes, and nanoparticles of different sizes and compositions are successfully distinguished. Sensitivity and limit of detection, related to particle number and mass concentration, are determined for several elements and particle diameters. (C) 2015 Elsevier Ltd. All rights reserved.

Time-resolved size and element analysis of gas-borne nanoparticles

Adrian Hess

Physical and chemical characterization of gas-borne particles in the nanometer to sub-micrometer size range is important in many applications, such as nanoparticle related health studies, the monitoring of powder or dust distribution processes, assessing the release of engineered nanoparticles (ENP) from ENP reinforced materials due to abrasion or combustion, or exposure studies related to ENP containing spray products. Such investigations are also highly valuable in the development of technical processes, e.g. to determine distinct size fractions containing specific elements or isotopes in terms of dealing with nuclear waste, or to evaluate particulate matter in process gases and emissions from thermal waste treatment, gas turbines, or other combustion engines. Such particle speciation includes knowledge about particle size distribution and chemical composition, and if possible obtained with a high time resolution. However, most of the available techniques are offline methods and/or not able to provide such physical and chemical information simultaneously. The Scanning Mobility Particle Sizer (SMPS) is a well-established and widely used equipment for determining size distribution and number concentration of such particles, within scan durations of a few minutes. Inductively Coupled Plasma Mass Spectrometry (ICPMS) is a highly sensitive multi-element technique, which allows determining the elemental composition of normally liquid samples, with excellent detection limits and a wide dynamic concentration range. In this work, SMPS and ICPMS are coupled to one hyphenated system. A Rotating Disk Diluter (RDD) allows directing a well-defined flow of a diluted aerosol into subsequent measuring equipment, which besides is mainly argon based, due to the dilution effect. Therefore an RDD is implemented as sample introduction interface, and the SMPS flow concept is re-designed to fulfil the requirements of both different analytical methods. This coupling strategy allows achieving simultaneous information on particle size and elemental composition, with SMPS-typical time resolutions of a few minutes, and offers high flexibility in terms of dealing with different aerosols, loaded with particles in the nanometer to sub-micrometer size range. Proper SMPS operation under argon atmosphere instead of air is validated. The developed setup is tested with a model aerosol containing air-borne silver nanoparticles. The capabilities are then demonstrated on uniformly composited metal aerosols, as well as an aerosol mixture containing smaller gold and larger silver nanoparticles. Sensitivity and limit of detection, related to particle number and mass concentration, are determined for several elements and particle diameters. After the successful characterization, the instrumentation is applied in two research applications. The first is a study on aerosol particles, released by commercial consumer spray products. In the second application, particulate metal emissions from the thermal treatment of differently impregnated wood samples are investigated, with the focus on alkali metals.

EPFL2016

A hyphenated SMPS-ICPMS coupling setup: Size-resolved element specific analysis of airborne nanoparticles

Adrian Hess, Christian Ludwig, Mohamed Tarik

Physical and chemical characterization of gas borne particles in the nanometer to sub micrometer size range includes knowledge about particle size distribution and chemical composition, possibly with a high time resolution. However, most of the available techniques are offline methods and/or not able to provide such physical and chemical information simultaneously. Scanning Mobility Particle Sizer (SMPS) is a well established and widely used technique for determining size distribution and number concentration of such particles, within scan durations of a few minutes. Inductively Coupled Plasma Mass Spectrometry (ICPMS) is a highly sensitive multi element technique, allowing the determination of elemental composition with excellent defection limits and a wide dynamic concentration range. In this work, SNIPS and ICPMS were coupled to one hyphenated system which allows achieving on-line and simultaneously size and chemical information with SMPS-Lypical time resolutions. A Rotating Disk Diluter was used as sample introduction interface, and the SMPS flow concept was re designed to fulfill the requirements of both different analytical methods. The developed setup was successfully tested with a model aerosol containing airborne silver nanoparticles. Proper SMPS operation under argon atmosphere instead of air was validated. The presented setup was applied to scan the particle size range from 7 to 156 um within 120s, Similar sensitivities and efficiencies compared to that of state-of-the-art SMPS and ICPMS instruments were achieved. (C) 2015 Elsevier Ltd. All rights reserved.

Elsevier Sci Ltd2015

Size-fractionated characterization and quantification of nanoparticle release rates from a consumer spray product containing engineered nanoparticles

Harald Hagendorfer, Christian Ludwig, Andrea Ulrich

This study describes methods developed for reliable quantification of size- and element-specific release of engineered nanoparticles (ENP) from consumer spray products. A modified glove box setup was designed to allow controlled spray experiments in a particle-minimized environment. Time dependence of the particle size distribution in a size range of 10-500 nm and ENP release rates were studied using a scanning mobility particle sizer (SMPS). In parallel, the aerosol was transferred to a size-calibrated electrostatic TEM sampler. The deposited particles were investigated using electron microscopy techniques in combination with image processing software. This approach enables the chemical and morphological characterization as well as quantification of released nanoparticles from a spray product. The differentiation of solid ENP from the released nano-sized droplets was achieved by applying a thermo-desorbing unit. After optimization, the setup was applied to investigate different spray situations using both pump and gas propellant spray dispensers for a commercially available water-based nano-silver spray. The pump spray situation showed no measurable nanoparticle release, whereas in the case of the gas spray, a significant release was observed. From the results it can be assumed that the homogeneously distributed ENP from the original dispersion grow in size and change morphology during and after the spray process but still exist as nanometer particles of size < 100 nm. Furthermore, it seems that the release of ENP correlates with the generated aerosol droplet size distribution produced by the spray vessel type used. This is the first study presenting results concerning the release of ENP from spray products.

Springer Verlag2010

Time-resolved size and element analysis of gas-borne nanoparticles

Adrian Hess

EPFL2016