Axel Zerrath

• PhD (Dr. rer. nat.)
• New Product Development at TSI Inc.

Counting efficiency of various aerosol materials in a new water-based nanoparticle counter (CPC) was investigated in the laboratory. Quantifying ambient city aerosol largely shows equivalency of water-based to butanol-based ultrafine particle counters. Size distribution measurements with either butanol-or water-based particle sizers are comparable...

The particle size distribution of urban aerosols is typically dominated by ultrafine particles (UFP) originating from local sources such as traffic and industrial emissions. Due to their negligible mass they are clearly underrepresented by legislative PM10 mass measurements. This is one reason why their contribution to urban air quality is better c...

Product purity, including knowledge of degradation and aggregation levels is addressed with various techniques for proteins and polymers. Ion mobility spectrometry of native macromolecules can simplify analysis without the need to work through fragmentation patterns. A macroion mobility spectrometer (MacroIMS) has been applied to routine analysis o...

The analysis of protein aggregates and fragments is an important step in ensuring stable production of protein products. Size exclusion chromatography (SEC) is a widely accepted method for measuring the size and quantity of soluble aggregates that is not without column-related challenges. Here we describe the use of nanoelectrospray ion mobility sp...

The MacroIMS System is an ion mobility spectrometry system that relies on first-principle size analysis to determine the molecular weight of macromolecules and complexes between 8 kDa and > 100 MDa. This technique reduces the breakdown of non-covalent interactions which typically accompany electrospray ionization through charge neutralization, allo...

The MacroIMS System is an ion mobility spectrometry system that relies on first-principle size analysis to determine the molecular weight of macromolecules and complexes between 8 kDa and > 100 MDa. This technique reduces the breakdown of non-covalent interactions which typically accompany electrospray ionization through charge neutralization, allo...

The MacroIMS system uses nanoelectrospray ionization (nano ESI) to convert solution-phase analytes into gas-phase macroions. The multiply-charged ions that are generated in the nano ESI process are charge-reduced to a repeatable, known charge distribution using a safe soft x-ray source. Resulting +1 charge state macroions are transported to the ion...

The MacroIMS System used in this study (Model 3982, TSI, Inc.) employs charge-reduced nanoelectrospray ionization to simplify charge distributions to a single-charged state, fast ion mobility separation, and single-ion counting to achieve high-mass analysis of intact molecules in the molecular mass range from kilodaltons to megadaltons. The front-e...

Nanoparticles are ubiquitous in both outdoor and indoor environments due to a large variety of natural and anthropogenic sources. Key parameters for characterizing nanoparticles include their size distribution and number concentration. A novel, portable and compact nanoparticle sizing instrument, the NanoScan SMPS, has been designed for application...

A novel instrument, the NanoScan SMPS (TSI 3910), is introduced here that provides the capability of employing well-established Scanning Mobility Particle Sizing (SMPS) technology in a format that can be easily utilized in the field. The use of a non-radioactive unipolar charger, radial Differential Mobility Analyzer (rDMA) and isopropanol-based Co...

Resuspended desert dust is an important air pollutant in both local and transboundary levels. Research on the resuspension and properties of desert road dust particulate matter (PM) was performed with dust samples from the provinces of Kandahar, Herat and Ghor in Afghanistan, and the province of Baghdad in Iraq. Measurements of the concentrations o...

A new technology to size nanoparticles in liquids is presented. The technique is based on aerosol technology coupled to a nanoparticle nebulizer. This allows number concentration measurements in the size range ca. 5 to 500 nm with high peak resolution.

Optical Particle Counters are in widespread use for measuring various aerosols including environmental monitoring. Since almost all optical particle counters and spectrometers are factory-calibrated with polystyrene latex (PSL) particles, sizing errors could be significant if the refractive indices of the aerosol are significantly different from th...

In order for the growing significance of nanotechnology to be addressed by occupational safety and health as well as from other aspects, workplace exposure to nanoparticles must be determined and examined. The quantity of measurement most frequently employed for nanoparticles is the particle number concentration. Seven contributions by six manufact...

In order for the growing significance of nanotechnology to be addressed by occupational safety and health as well as from other aspects, workplace exposure to nanoparticles must be determined and examined. The quantity of measurement most frequently employed for nanoparticles is the particle number concentration. Seven contributions by six manufact...

An electrical low pressure impactor (ELPI) was used to study atmospheric aerosol particle number, surface, and mass concentrations and size distributions over a diameter range of 7 nm–10 μm at urban, rural and high-alpine locations along an alpine altitude transect across Southern Germany. The measurements were performed in the city of Munich and a...

Mass spectrometry (MS) has advanced to analyze ever-larger biomolecules with the invention of soft ionization techniques like electrospray ionozation (ESI). Although ESI has provided a method of generating ions of high mass, mass spectrometers generally suffer both lower sensitivity and lower resolution as the mass-to-charge ratio of an ion increas...

Continuous-flow, thermally diffusive condensation particle counters (CPC’s) that use n-butyl alcohol (butanol) as their working fluid have been used to measure aerosol particles for more than 30 years. A new, completely redesigned general-purpose butanol CPC was developed at the end of 2005. Just one year prior to that a continuous, laminar-flow wa...

In this study calibration measurements of new TSI condensation particle counter models, using either butanol or water as working fluid, are described. Experiments were carried our at ambient, laboratory conditions for two particle materials, silver and sodium chloride. The obtained counting efficiency curves are presented.

Condensation particle counters (CPCs) are well suited to measure the number concentration of small airborne particles. Continuous-flow, thermally diffusive CPCs that utilize n-butyl alcohol (butanol) as the condensing vapour have been developed in the late 1970s (Bricard et al., 1976). The first commercial model of this type, the CNC 3020 (TSI Inc....

Stolzenburg and McMurry (1991) developed the first ultrafine condensation particle counter (UCPC). TSI subsequently commercialized the UCPC (model 3025) leading to wide use of the instrument. It was the first CPC specifically developed for detecting ultrafine aerosol particles with particle diameters smaller than 20 nanometers. Recently a new butan...

Urban aerosol is typically dominated by ultrafine particles which often originate from local sources such as traffic and industrial emissions. Ultrafine particles are not well represented by PM10 or PM2.5 measurements. We investigated the physical properties of the urban aerosol in a light industrial area near a freeway and in close proximity to a...

Ausgehend von den Grundlagen der Partikelmessmethoden für Durchmesser, Anzahl und Masse und einer Darstellung der physikalischen Wirkprinzipien werden die wichtigsten Messgeräte zur Bestimmung dieser Partikelemissionen vorgestellt. Im Einzelnen sind dies für die Anzahlverteilungsbestimmung das SMPS, EEPS und das ELPI. Für die Massenbestimmung werde...

Atmospheric aerosol samples from urban, rural and alpine locations have been chemical analyzed. The focus of the analyis was on carbon compounds, especially carbohydrates cellulose and glucose. Cellulose content in the samples could be determined by hydrolysis and anion exchange chromatography and enzymatic tests. The second part of this work shows...

The physical and chemical characterisation of alpine aerosols is one of the central ob- jectives of the research project SCAVEX (Schneefernerhaus Aerosol and Reactive Ni- trogen Experiment), which was started in 2001. The techniques applied during the first comprehensive aerosol measurement campaigns at the GAW observatory Schneefern- erhaus on Mou...

Several studies have shown that carbonaceous components contribute significantly to the composition of tropospheric aerosols and thus influence their chemical, optical and microphysical properties. Climatic effects as well as health effects are related to the chemical composition of the aerosol particles, but only very limited experimental data on...