Wet Aerosol Research Articles

Quantifying exposure risk: Surgical masks and respirators

The interaction between the source of respiratory infectious aerosols and the receiver has not been investigated. Using a bench model, we measured the effects of filtration and deflection achieved with surgical masks and N95 respirators. We constructed a chamber designed to produce radiolabeled wet aerosols simulating contaminated particles exhaled during tidal breathing (source). Particles within the chamber were exposed to either 6 or 0 air exchanges/hr. Aerosols were defined by cascade impaction. Source aerosols were exhaled via a ventilated mannequin head suitable for mask protection. A similar ventilated head within the chamber assessed recipient exposure (receiver). A filter within the receiver quantified exposure. Two types of masks, an N95 respirator and surgical mask, were tested. Data were presented as percent of nebulized particles on the receiver filter (exposure) and simulated workplace protection factor (sWPF). In the presence of chamber air exchange, applying a mask on the source (primarily deflection) resulted in significant reduction in exposure to the receiver (sWPF170-320). Masks on receiver (filtration) did not significantly reduce exposure from that of no masks (sWPF1.37-2.21), except with a Vaseline seal (sWPF118). With 0 air exchanges/hr, only Vaseline seal was effective in reducing exposure (sWPF 16-101). In a ventilated space, deflection of exhaled particles with a mask worn at the source achieved far greater levels of protection than any mask on the receiver. Mask filtration at source or receiver did not play a significant role in reducing exposure.

A closure study of aerosol hygroscopic growth factor during the 2006 Pearl River Delta Campaign

Measurements of aerosol physical, chemical and optical parameters were carried out in Guangzhou, China from 1 July to 31 July 2006 during the Pearl River Delta Campaign. The dry aerosol scattering coefficient was measured using an integrating nephelometer and the aerosol scattering coefficient for wet conditions was determined by subtracting the sum of the aerosol absorption coefficient, gas scattering coefficient and gas absorption coefficient from the atmospheric extinction coefficient. Following this, the aerosol hygroscopic growth factor, f(RH), was calculated as the ratio of wet and dry aerosol scattering coefficients. Measurements of size-resolved chemical composition, relative humidity (RH), and published functional relationships between particle chemical composition and water uptake were likewise used to find the aerosol scattering coefficients in wet and dry conditions using Mie theory for internally- or externally-mixed particle species [(NH4)2SO4, NH4NO3, NaCl, POM, EC and residue]. Closure was obtained by comparing the measured f(RH) values from the nephelometer and other in situ optical instruments with those computed from chemical composition and thermodynamics. Results show that the model can represent the observed f(RH) and is appropriate for use as a component in other higher-order models.

Hygroscopic growth of atmospheric aerosol sampled in Prague 2008 using humidity controlled inlets

Atmospheric aerosol was sampled at different humidity conditions using two 7-stage modified BLPI impactors. Dry particles were obtained at 20% RH. Wet particles were humidified inside diffuse humidifier with output 85–90% RH. 11 parallel intakes of dry and wet aerosol were done during winter campaign and 10 during summer one. The samples were processed by gravimetric method, ion chromatography and WSOC analysis. The average mass concentration sampled in winter was 34.4μg/m3 at dry, whereas the average mass concentration obtained at wet conditions was slightly higher 37.2μg/m3. The average of summer concentration was 21.4μg/m3 at dry conditions, and 21.6μg/m3 at wet conditions. Theoretical mass-size distribution of wet aerosol determined from dry aerosol data was calculated using the most abundant hygroscopic inorganic anions SO42−, NO3−, Cl−, and WSOC fractions were only taken into account. Calculated distribution estimates the growth of particles due to water uptake and predicts the size distribution of wet aerosol. The growth factors based on Stokes and aerodynamic diameters were calculated. Measured differences in dry and wet size distributions of single species pointed to externally mixed particles and/or changes in aerosol composition during sampling.

Organosulfates from glycolaldehyde in aqueous aerosols and clouds: Laboratory studies

Secondary organic aerosol (SOA) formation is enhanced on acidic seed particles; SOA also forms during cloud processing reactions where acidic sulfate is prevalent. Recently several studies have focused on the identification of organosulfates in atmospheric aerosols or smog chamber experiments, and upon the mechanism of formation for these products. We identify several organosulfate products formed during the laboratory OH radical oxidation of dilute aqueous glycolaldehyde in the presence of sulfuric acid. We propose a radical–radical reaction mechanism as being consistent with formation of these products under our experimental conditions. Using a kinetics model we estimate that organosulfates account for less than 1% of organic matter formed from these precursors during cloud processing. However, in wet acidic aerosols, where precursors are highly concentrated and acidic sulfate makes up close to half of the aerosol mass, this radical–radical reaction could account for significant organosulfate production.

A comparison of dry and wet season aerosol number fluxes over the Amazon rain forest

Abstract. Vertical number fluxes of aerosol particles and vertical fluxes of CO2 were measured with the eddy covariance method at the top of a 53 m high tower in the Amazon rain forest as part of the LBA (The Large Scale Biosphere Atmosphere Experiment in Amazonia) experiment. The observed aerosol number fluxes included particles with sizes down to 10 nm in diameter. The measurements were carried out during the wet and dry season in 2008. In this study focus is on the dry season aerosol fluxes, with significant influence from biomass burning, and these are compared with aerosol fluxes measured during the wet season. Net particle deposition fluxes dominated in daytime in both seasons and the deposition flux was considerably larger in the dry season due to the much higher dry season particle concentration. The particle transfer velocity increased linearly with increasing friction velocity in both seasons. The difference in transfer velocity between the two seasons was small, indicating that the seasonal change in aerosol number size distribution is not enough for causing any significant change in deposition velocity. In general, particle transfer velocities in this study are low compared to studies over boreal forests. The reasons are probably the high percentage of accumulation mode particles and the low percentage of nucleation mode particles in the Amazon boundary layer, both in the dry and wet season, and low wind speeds in the tropics compared to the midlatitudes. In the dry season, nocturnal particle fluxes behaved very similar to the nocturnal CO2 fluxes. Throughout the night, the measured particle flux at the top of the tower was close to zero, but early in the morning there was an upward particle flux peak that is not likely a result of entrainment or local pollution. It is possible that these morning upward particle fluxes are associated with emission of primary biogenic particles from the rain forest. Emitted particles may be stored within the canopy during stable conditions at nighttime, similarly to CO2, and being released from the canopy when conditions become more turbulent in the morning.

Low power cross-flow atmospheric pressure Ar + He plasma jet : Spectroscopic diagnostic and excitation capabilities

A cross-flow atmospheric plasma jet with distilled water or analyte solution nebulization has been investigated. The plasma gas flows perpendicularly to the RF powered electrode (11.21 MHz) and a grounded electrode was added for plasma stabilization. The working parameters of the plasma generator can be controlled in order to maximize either the plasma power (75 W) or the voltage on the RF powered electrode (plasma power, 40 W). The plasma gas, pure argon (0.4 l min − 1) or a mixture of argon (0.3–0.4 l min − 1) and helium (0–0.2 l min − 1), was also used for liquid nebulization. Optical emission of the plasma, collected in the normal viewing mode, was used for plasma diagnostics and for evaluating its excitation capabilities. The influence of helium content in the mixed-gas plasma on the plasma characteristics and on the emission axial profiles of the plasma gas constituents and of the analytes originate from the wet aerosol was studied. The addition of helium to the argon plasma, generally determines decreases in the emission of the plasma gas constituents (with the exception of molecular nitrogen), in the rotational temperature and in the electron number density and increases in the excitation temperatures and in the emission of easily excitable analytes. Based on the determined electron number densities, it was concluded that in the plasma zone which presents interest from analytical point of view the plasma is not very far from the partial thermodynamic equilibrium. In function of the helium content in the plasma gas and of the axial distance from the powered electrode the excitation temperatures are in the range of 2420–3340 K for argon, 2500–5450 K for oxygen and 900–2610 K for ionic calcium and the electron number densities are in the range of 1.2 10 12–1.25 10 13 cm − 3. Some elements with excitation energy lower than 6 eV were excited in the plasma. The plasma excitation capability depends on the working conditions of the plasma generator (maximum power or maximum voltage on the RF powered electrode) and on the helium content in the mixed-gas plasma. The estimated detection limits for the studied elements (Na, Li, K, Ca, Cu, Ag, Cd, Hg and Zn) are in the range of 7 ng ml − 1 to 28 μg ml − 1.

Progress in understanding key aerosol issues

The 6th FWP SARNET project launched a set of studies to enhance understanding and predictability of relevant-risk scenarios where uncertainties related to aerosol phenomena were still significant: retention in complex structures, such as steam generator by-pass SGTR sequences or cracks in concrete walls of an over-pressurised containment, and primary circuit deposit remobilization, either as vapours (revaporisation) or aerosols (resuspension). This paper summarizes the major advances achieved. Progress has been made on aerosol scrubbing in complex structures. Models based on empirical data (ARISG) and improvements to previous codes (SPARC) have been proposed, respectively, for dry and wet aerosol retention, but, further development and validation remains, as was noted during the ARTIST international project and potential successors. New CFD models for particle-turbulence interactions have been developed based on random walk stochastic treatments and have shown promise in accurately describing particle deposition rates in complex geometries. Aerosol transport in containment concrete cracks is fairly well understood, with several models developed but validation was limited. Extension of such validation against prototypic data will be feasible through an ongoing joint experimental program in the CEA COLIMA facility under the 6th Framework PLINIUS platform. Primary deposit revaporisation has been experimentally demonstrated on samples from the Phebus-FP project. Data review has pinpointed variables affecting the process, particularly temperature. Available models have been satisfactorily used to interpret separate-effect tests, but performing integral experiments, where revaporisation is likely combined with other processes, still pose a difficult challenge. Further experimental data as well as modelling efforts seem to be necessary to get a full understanding. Resuspension, sometimes referred to as mechanical remobilization, has been recently addressed in SARNET and although a set of models were already available in the literature (i.e., Rock'n Roll model, CESAR, ECART), further work is needed to extend current capabilities to multi-layer deposits and to produce simplified, but sufficiently accurate, models. A major remaining uncertainty is the particle-to-particle/wall adhesion and its dependence on microscale roughness. Data from the previous EU STORM project have been retrieved and further experiments designed for code validation are being used to benchmark the models.

Effects of Precursor Concentration and Acidic Sulfate in Aqueous Glyoxal−OH Radical Oxidation and Implications for Secondary Organic Aerosol

Previous experiments demonstrated that aqueous OH radical oxidation of glyoxal yields low-volatility compounds. When this chemistry takes place in clouds and fogs, followed by droplet evaporation (or if it occurs in aerosol water), the products are expected to remain partially in the particle phase, forming secondary organic aerosol (SOA). Acidic sulfate exists ubiquitously in atmospheric water and has been shown to enhance SOA formation through aerosol phase reactions. In this work, we investigate how starting concentrations of glyoxal (30−3000 μM) and the presence of acidic sulfate (0−840 μM) affect product formation in the aqueous reaction between glyoxal and OH radical. The oxalic acid yield decreased with increasing precursor concentrations, and the presence of sulfuric acid did not alter oxalic acid concentrations significantly. A dilute aqueous chemistry model successfully reproduced oxalic acid concentrations, when the experiment was performed at cloud-relevant concentrations (glyoxal <300 μM), but predictions deviated from measurements at increasing concentrations. Results elucidate similarities and differences in aqueous glyoxal chemistry in clouds and in wet aerosols. They validate for the first time the accuracy of model predictions at cloud-relevant concentrations. These results suggest that cloud processing of glyoxal could be an important source of SOA.

Laboratory measurements of the optical properties of sea salt aerosol

Abstract. The extinction spectra of laboratory generated sea salt aerosols have been measured from 1 μm to 20 μm using a Bruker 66v/S FTIR spectrometer. Concomitant measurements include temperature, pressure, relative humidity and the aerosol size distribution. The refractive indices of the sea salt aerosol have been determined using a simple harmonic oscillator band model (Thomas et al., 2004) for aerosol with relative humidities at eight different values between 0.4% to 86%. The resulting refractive index spectra show significant discrepancies when compared to existing sea salt refractive indices calculated using volume mixing rules (Shettle and Fenn, 1979). Specifically, an additional band is found in the refractive indices of dry sea salt aerosol and the new data shows increased values of refractive index at almost all wavelengths. This implies that the volume mixing rules, currently used to calculate the refractive indices of wet sea salt aerosols, are inadequate. Furthermore, the existing data for the real and imaginary parts of the refractive indices of dry sea salt aerosol are found not to display the Kramers-Kronig relationship. This implies that the original data used for the volume mixing calculations is also inaccurate.

Heterogeneous loss of HO 2 by KCl, synthetic sea salt, and natural seawater aerosol particles

The HO 2 uptake to aerosol particles is potentially significant sink for the HO 2 radical in the marine atmosphere. To assess the heterogeneous loss of HO 2 on marine aerosol particles, we have investigated the uptake coefficients ( γ) of HO 2 for submicron aerosol particles of KCl, synthetic sea salt, and natural seawater under ambient conditions (760 Torr and 296 ± 2 K) using an aerosol flow tube (AFT) coupled with a chemical conversion/laser-induced fluorescence (CC/LIF) technique. γ values determined for dry and wet aerosols of KCl were 0.02 ± 0.01 and 0.07 ± 0.03 at 66% and 75% RH, respectively, while γ values for those doped with CuSO 4 was 0.55 ± 0.19 at 75% RH. γ values determined for synthetic sea-salt particles were 0.07 ± 0.03, 0.12 ± 0.04 and 0.13 ± 0.04 at 35%, 50%, 75% RH, respectively, while γ values for natural seawater particles were 0.10 ± 0.03, 0.11 ± 0.02 and 0.10 ± 0.03 at 35%, 50%, 75% RH, respectively. We recommend a HO 2 uptake coefficient in marine areas of 0.1 for modeling and estimated the contribution of heterogeneous loss of HO 2 by sea-salt aerosol particles in marine areas using a box model. Our box-model simulations suggested that daytime maximum HO 2 concentrations decreased to 87–94% of the values without heterogeneous loss.

V / Q-Szintigrafie zur Diagnostik der Lungenembolie – I. Durchführung und Beurteilung

V / Q scintigraphy remains even today exceptionally well-suited for diagnosis of pulmonary embolism. The combination of ventilation and perfusion scintigraphy in this sequence is standard. Suitable tracers for ventilation scintigraphy are Technegas and Krypton-81m, with wet aerosols as second-choice alternatives. Acquisition in SPECT-technique is optimal. Regional perfusion defects with maintained ventilation (V / Q mismatch) correlate to pulmonary embolism without diagnostic limitations. Evaluation by means of PIOPED criteria should be rejected. Increased attention should be paid to partially-occluding embolisms, since they also influence the prognosis. Relevant alternative diagnoses refer to respiratory tract obstruction (V / Q match with intact v. Euler-Liljestrand reflex) and functional right-left shunt (V / Q reverse mismatch with impaired v. Euler-Liljestrand reflex).

Differentiation of the drying time of paints by dynamic speckle interferometry

This work is part of studies of drying of paints using dynamic speckle interferometry (DSI), a technique based on the use of laser light. DSI is a non-invasive method that does not disturb the drying process. The sample is illuminated by a laser light from a source and the images corresponding to a phenomenon of interference called speckle are registered. If the surface shows activity, the interference pattern changes in time. Following this evolution, we can analyze the drying process by means of an image-processing algorithms. Therefore, it is possible to determine the temporal evolution of surfaces with different drying times. In this work the application of DSI to follow the drying process of paints with different drying times and drying velocities is presented. Different types of paints applied in different thicknesses of wet film and aerosol spray were analyzed. Quantitative measurements were obtained by analysis of the inertia moment of the co-occurrence matrix. Also, qualitative measurements were obtained by sample activity. A new approach for monitoring simultaneously zones with different drying times is discussed and applied. As in previous work, results were compared with those from conventional techniques such as gravimetric analysis providing a good correlation between both techniques.

Investigation of Droplet Size Distributions and Drizzle Formation Using a New Trajectory Ensemble Model. Part I: Model Description and First Results in a Nonmixing Limit

Abstract A novel trajectory ensemble model of a stratocumulus cloud is described. In this model, the boundary layer (BL) is fully covered by a great number of Lagrangian air parcels that during their motion can contain either wet aerosols or aerosols and droplets. The diffusion growth of aerosols and droplets, as well as drop collisions, is accurately described in each parcel. Droplet sedimentation is taken into account, which allows simulation of precipitation formation. The Lagrangian parcels are advected by the velocity field generated by the turbulent-like flow model obeying turbulent correlation laws. The output of the numerical model includes droplet and aerosol size distributions and their moments, such as droplet concentration, droplet spectrum width, cloud water content, drizzle content, radar reflectivity, etc., calculated in each parcel. Horizontally averaged values are calculated as well. Stratocumulus clouds observed during two research flights (RF01 and RF07) in the Second Dynamics and Chemistry of Marine Stratocumulus (DYCOMS II) field campaign are simulated. A good agreement between the dynamical and microphysical structures simulated by the model with observations is obtained even in the nonmixing limit. A crucial role of sedimentation for the creation of a realistic cloud microphysical structure is demonstrated. In sensitivity studies, the statistical stability of the model is analyzed. Applications of the model for the investigation of droplet size distribution and drizzle formation are discussed, as is the possible utilization of the model for remote sensing applications.

The role of boundary layer aerosol particles for the development of deep convective clouds: A high-resolution 3D model with detailed (bin) microphysics applied to CRYSTAL-FACE

This paper reproduces aircraft microphysical measurements using a three-dimensional model with bin resolved microphysics and is then used to analyze in particular the role of boundary layer aerosol particles in the anvil and the ice phase. The simulated case is a convective cloud which develops a large anvil of around 10 km height, which was sampled during the Cirrus Regional Study of Tropical Anvils and Cirrus Layers — Florida Area Cirrus Experiment (CRYSTAL-FACE). The model couples the 3D dynamics of a cloud scale model with a detailed mixed phase microphysical code. The microphysical package considers the evolution of the wet aerosol particles, drop and ice crystal spectra on size grids with 39 bins. With this model hereafter called DESCAM 3D, we are able to simulate the cloud with features close to those observed and to provide explanations of the observed phenomena concerning cloud microphysics as well as cloud dynamics. The same CRYSTAL-FACE cloud has already been simulated by other groups using a similar model. They investigated the role of mid-tropospheric aerosol particles versus boundary layer aerosol on the microphysical properties of the anvil. Similar simulations with our DESCAM 3D lead to quite different results. Reducing the number of mid-tropospheric aerosol particles causes only minor changes in the cloud anvil. However, changing the aerosol particle spectrum in the boundary layer from clean to polluted conditions modifies strongly the dynamical evolution of the convective clouds and thus impacts significantly on the microphysical properties of the anvil. Possible reasons for the differences are discussed.

Optical properties of single mixed-phase aerosol particles

We examine the light scattering from wet aerosol particles whose core morphology is a random Gaussian sphere coated by different amounts of water. We compare the results with those calculated from a concentric-sphere particle and from a homogeneous-sphere particle whose refractive index is determined from the Bruggeman mixing rule. In nearly all cases the differences between those of the Gaussian-core and the concentric-sphere particles are small. The most significant differences are seen in calculations of the asymmetry parameters and the intensity and polarization phase functions. The results of the homogeneous-sphere particles vary significantly from those of the Gaussian-core particles, typically an order of magnitude greater than for the concentric-sphere particles. It is not uncommon to see differences of 10% in the efficiencies of large, homogeneous-sphere particles; whereas, in the intensity and polarization phase functions, differences of several tens of percent are not uncommon.

Kinetics of Heterogeneous Reactions of HO2 Radical at Ambient Concentration Levels with (NH4)2SO4 and NaCl Aerosol Particles

The HO2 uptake coefficient (gamma) for inorganic submicrometer wet and dry aerosol particles ((NH4)2SO4 and NaCl) under ambient conditions (760 Torr and 296 +/- 2 K) was measured using an aerosol flow tube (AFT) coupled with a chemical conversion/laser-induced fluorescence (CC/LIF) technique. The CC/LIF technique enabled experiments to be performed at almost the same HO2 radical concentration as that in the atmosphere. HO2 radicals were injected into the AFT through a vertically movable Pyrex tube. Injector position-dependent profiles of LIF intensity were measured as a function of aerosol concentration. Measured gamma values for dry aerosols of (NH4)2SO4 were 0.04 +/- 0.02 and 0.05 +/- 0.02 at 20% and 45% relative humidity (RH), respectively, while those of NaCl were <0.01 and 0.02 +/- 0.01 at 20% and 53% RH, respectively. For wet (NH4)2SO4 aerosols, measured gamma values were 0.11 +/- 0.03, 0.15 +/- 0.03, 0.17 +/- 0.04, and 0.19 +/- 0.04, at 45%, 55%, 65%, and 75% RH, respectively, whereas for wet NaCl aerosols the values were 0.11 +/- 0.03, 0.09 +/- 0.02, and 0.10 +/- 0.02 for 53%, 63%, and 75% RH, respectively. Wet (NH4)2SO4 and NaCl aerosols doped with CuSO4 showed gamma values of 0.53 +/- 0.12 and 0.65 +/- 0.17, respectively. These results suggest that compositions, RH, and phase for aerosol particles are significant to HO2 uptake. Potential HO2 loss processes and their atmospheric contributions are discussed.

A low-flow low-power helium microwave induced plasma for optical and mass spectrometry with solution nebulization

A low-flow low-power annular-shaped microwave induced helium plasma operating at atmospheric pressure has been developed for use in optical emission as well as mass spectrometry. The first study on the plasma formation and fundamental investigation of the plasma generated at helium flow rate below 3 L min−1 by the new TEM cavity based MIP system is described. Radial profiles of emission spectra provide He excitation temperature (Texc) of 3000–3300K and electron number density (ne) of 5.5–7.5 × 1014 cm−3. To demonstrate the plasma robustness, both the tolerance for water loading and the excitation capability for metals and nonmetals were investigated using ultrasonic nebulization for wet aerosol introduction into the plasma. Detection limits data are shown for some elements and compared with those obtained using other MIP systems.

A magnetically excited microwave plasma source for atomic emission spectroscopy with performance approaching that of the inductively coupled plasma

A novel magnetically excited microwave plasma emission source was developed and tested. Unlike previous microwave plasma sources which couple energy from the microwave electric field, this source couples energy from the magnetic field. The resultant plasma shape allows easy entrainment of wet sample aerosol, such as is produced by a conventional inductively coupled plasma (ICP) nebulizer and spray chamber, into the core of the plasma. Plasma support gas can be either nitrogen or air although better sensitivity is achieved using nitrogen. Good stability of operation was observed for both aqueous and organic solvents over a wide range of sample flows. The measured performance when used as a spectroscopic source in conjunction with an echelle polychromator showed detection limits approaching those of commercial ICP sources.

In Vitro Performance Testing of the Novel Medspray® Wet Aerosol Inhaler Based on the Principle of Rayleigh Break-up

PurposeA new inhaler (Medspray®) for pulmonary drug delivery based on the principle of Rayleigh break-up has been tested with three different spray nozzles (1.5; 2.0 and 2.5 μm) using aqueous 0.1% (w/w) salbutamol and 0.9% (w/w) sodium chloride solutions.Materials and methodsParticle size distributions in the aerosol were measured with the principles of time of flight (APS) and laser diffraction (LDA).ResultsThe Medspray® inhaler exhibits a highly constant droplet size distribution in the aerosol during dose emission. Droplets on the basis of Rayleigh break-up theory are monodisperse, but due to some coalescence the aerosols from the Medspray® inhaler are slightly polydisperse. Mass median aerodynamic diameters at 60 l.min−1 from APS are 1.42; 1.32 and 1.27 times the theoretical droplet diameters (TD’s) and median laser diffraction diameters are 1.29; 1.14 and 1.05 times TD for 1.5; 2.0 and 2.5 μm nozzles (TD: 2.84; 3.78 and 4.73 μm respectively).ConclusionsThe narrow particle size distribution in the aerosol from the Medspray® is highly reproducible for the range of flow rates from 30 to 60 l.min−1. The mass median aerodynamic droplet diameter can be well controlled within the size range from 4 to 6 μm at 60 l.min−1.

Introducing wet aerosols into the static high sensitivity ICP (SHIP)

A demountable design of the static high sensitivity ICP (SHIP) for optical emission spectrometry is presented, and its use as an excitation source with the introduction of wet aerosols was investigated. Aerosols were produced by standard pneumatic sample introduction systems, namely a cross flow nebulizer, Meinhard nebulizer and PFA low flow nebulizer, which have been applied in conjunction with a double pass and a cyclonic spray chamber. The analytical capabilities of these sample introduction systems in combination with the SHIP system were evaluated with respect to the achieved sensitivity. It was found that a nebulizer tailored for low argon flow rates (0.3-0.5 L min(-1)) is best suited for the low flow plasma (SHIP). An optimization of all gas flow rates of the SHIP system with the PFA low flow nebulizer was carried out in a two-dimensional way with the signal to background ratio (SBR) and the robustness as optimization target parameters. Optimum conditions for a torch model with 1-mm injector tube were 0.25 and 0.36 L min(-1) for the plasma gas and the nebulizer gas, respectively. A torch model with a 2-mm injector tube was optimized to 0.4 L min(-1) for the plasma gas and 0.44 L min(-1) for the nebulizer gas. In both cases the SHIP system saves approximately 95% of the argon consumed by conventional inductively coupled plasma systems. The limits of detection were found to be in the low microgram per litre range and below for many elements, which was quite comparable to those of the conventional setup. Furthermore, the short-term stability and the wash out behaviour of the SHIP were investigated. Direct comparison with the conventional setup indicated that no remarkable memory effects were caused by the closed design of the torch. The analysis of a NIST SRM 1643e (Trace Elements in Water) with the SHIP yielded recoveries of 97-103% for 13 elements, measured simultaneously.