Development and characterization of a single particle laser ablation mass spectrometer (SPLAM) for organic aerosol studies

A single particle instrument was developed for real-time analysis of organic aerosol. This instrument, named Single Particle Laser Ablation Mass Spectrometry (SPLAM), samples particles using an aerodynamic lens system for which the theoretical performances were calculated. At the outlet of this system, particle detection and sizing are realized by using two continuous diode lasers operating at λ = 403 nm. Polystyrene Latex (PSL), sodium chloride (NaCl) and dioctylphtalate (DOP) particles were used to characterize and calibrate optical detection of SPLAM. The optical detection limit (DL) and detection efficiency (DE) were determined using size-selected DOP particles. The DE ranges from 0.1 to 90% for 100 and 350 nm DOP particles respectively and the SPLAM instrument is able to detect and size-resolve particles as small as 110–120 nm. During optical detection, particle scattered light from the two diode lasers, is detected by two photomultipliers and the detected signals are used to trigger UV excimer laser (λ = 248 nm) used for one-step laser desorption ionization (LDI) of individual aerosol particles. The formed ions are analyzed by a 1 m linear time-of-flight mass spectrometer in order to access to the chemical composition of individual particles. The TOF-MS detection limit for gaseous aromatic compounds was determined to be 0.85 × 10<sup>−15</sup> kg (∼4 × 10<sup>3</sup> molecules). DOP particles were also used to test the overall operation of the instrument. The analysis of a secondary organic aerosol, formed in a smog chamber by the ozonolysis of indene, is presented as a first application of the instrument. Single particle mass spectra were obtained with an effective hit rate of 8%. Some of these mass spectra were found to be very different from one particle to another possibly reflecting chemical differences within the investigated indene SOA particles. Our study shows that an exhaustive statistical analysis, over hundreds of particles, and adapted reference mass spectra are further needed to understand the chemical meaning of single particle mass spectra of chemically complex submicrometer-sized organic aerosols

Development of a portable reference aerosol generator (PRAG) for calibration of particle mass concentration measurements

International audienceThe tapered element oscillating microbalance with filter dynamics measurement system (TEOM-FDMS) is an instrument commonly employed by the French air quality monitoring network. This instrument is currently calibrated with calibration weights traceable to SI but having value and mass differences between each of them that are not representative of real atmospheric particle mass measurements. Moreover, these calibration weights do not allow detection of any technical problems associated with either the TEOM-FDMS sampling system upstream of the mass measurement or the intrinsic TEOM-FDMS filtration system. Therefore, a calibration method was developed using a portable reference aerosol generator (PRAG) that produces known and stable particle mass concentrations over time. Here, we present the characterization of the PRAG system in terms of a reference range of particle masses between 30 ± 10 and 3456 ± 83 μg at three sampling times. Its coupling with the TEOM-FDMS and a global comparison between the defined reference range of particle masses and the measured masses obtained with each TEOM-FDMS implicated in this study are also presented. © 2017 Chinese Society of Particuology and Institute of Process Engineering, Chinese Academy of Science

Characterization of aerosols generated from nine nanomaterial powders reliability with regard to in vivo inhalation toxicology studies

International audienceIn experimental toxicology, when simulating human exposure to aerosols in the working environment, inhalation is the route of administration of choice for evaluating the toxicity of a given material (in aerosol form) in animals. In this context, this work aimed to contribute to the establishment of recommendations concerning the characterization of aerosol tests in inhalation toxicology studies. In particular, the work consisted of experimentally characterizing test aerosols using a given generation method to be used for inhalation toxicology studies. Nine nanomaterial powders have been investigated (four types of TiO2, two types of SiO2, ZnO, CeO, and BaSO4). The aerosols produced cover the particle size range from a few tens of nanometers up to several micrometers and are mainly composed of aggregates and/or agglomerates. The work carried out shows that generation and characterization of test aerosols for inhalation toxicology studies is a complex but essential element of inhalation studies, for which the conditions required (stability, repeatability, level of concentration) are sometimes difficult to obtain. Moreover, this study highlights the necessity to carry out preliminary tests to ascertain the performances of the chosen devices and their suitability for inhalation toxicology. © 2018, Springer Nature B.V

In vivo evaluation of the potential neurotoxicity of aerosols released from mechanical stress of nano-TiO2 additived paints in mice chronically exposed by inhalation

Engineered Nanomaterials (ENM) provide technical and specific benefits due to theirphysical-chemical properties at the nanometer scale. For instance, many ENM are used to improveproducts in the building industry. Nanoscaled titanium dioxide (TiO2) is one of the most used ENM inthis industry. Incorporated in different matrix, cement, glass, paints… TiO2 nanoparticles (NPs) providethe final product with anti-UV, air purification and self-cleaning properties, thanks to theirphotocatalytic activity. However, ageing processes of such products, as photocatalytic paints, during amechanical stress have been shown to release TiO2 NPs from this matrix associated with sanding dust.Thus, workers who sand painted walls could be exposed to TiO2 NPs through inhalation. As inhalationmay lead to a translocation of particulate matter to the brain via olfactory or trigeminal nerves, there isan urgent need for evaluating a potential neurotoxicity. In order to provide new knowledge on this topic,we developed a dedicated experimental set-up using a rodent model exposed via inhalation. The aerosolreleased from a mechanical stress of photocatalytic paints containing TiO2 NPs was characterized andcoupled to an exposition chamber containing group of mice free to move and chronically exposed(2 hours per day for 5 days a week during 8 weeks)

VUV photoionization of gas phase adenine and cytosine: A comparison between oven and aerosol vaporization

International audienceWe studied the single photon ionization of gas phase adenine and cytosine by means of vacuum ultraviolet synchrotron radiation coupled to a velocity map imaging electron∕ion coincidence spectrometer. Both in-vacuum temperature-controlled oven and aerosol thermodesorption were successfully applied to promote the intact neutral biological species into the gas phase. The photoion yields are consistent with previous measurements. In addition, we deduced the threshold photoelectron spectra and the slow photoelectron spectra for both species, where the close to zero kinetic energy photoelectrons and the corresponding photoions are measured in coincidence. The photoionization close and above the ionization energies are found to occur mainly via direct processes. Both vaporization techniques lead to similar electronic spectra for the two molecules, which consist of broadbands due to the complex electronic structure of the cationic species and to the possible contribution of several neutral tautomers for cytosine prior to ionization. Accurate ionization energies are measured for adenine and cytosine at, respectively, 8.267 ± 0.005 eV and 8.66 ± 0.01 eV, and we deduce precise thermochemical data for the adenine radical cation. Finally, we performed an evaluation and a comparison of the two vaporization techniques addressing the following criteria: measurement precision, thermal fragmentation, sensitivity, and sample consumption. The aerosol thermodesorption technique appears as a promising alternative to vaporize large thermolabile biological compounds, where extended thermal decomposition or low sensitivity could be encountered when using a simple oven vaporization technique

VUV spectroscopy and photochemistry of five interstellar and putative prebiotic molecules

For many years, our group has been investigating the VUV spectroscopy and photochemistry of molecules of astrophysical (Jochims et al. 200

An intercomparison exercise of good laboratory practices for nano-aerosols sizemeasurements by mobility spectrometers

International audienceAn intercomparison campaign on nanoparticle size measurement was organized in the frame of the French nanoMetrology club. The aim of this study is to make an inventory of the metrological capabilities of all measurement techniques in France involved in the “nano” size range, including the SMPS (Scanning Mobility Particle Sizer) concerning aerosol metrology. For this study, four samples have been proposed, namely (1) - a SiO2 colloidal suspension (FD304) consisting of a monomodal population, (2) - two samples consisting of two nanoparticle populations of SiO2 having proportions to be determined and (3) - a TiO2 colloidal suspension. Ten SMPS associated to five participants around a common experimental setup were performed in link with a control SMPS to have simultaneous measurements with a same instrument in each laboratory in parallel with the SMPS used by each partner. This article presents SMPS results of this study associated with the description of the experimental set-up and the sample preparation protocol with an identified schedule and comparison with SEM measurements. The present paper does not focus on the actual capability of the tested mobility spectrometers, but aims to highlights the good laboratory practices using their own but common resources in terms of aerosol generation and measurement set-ups

Impact of batch variability on physicochemical properties of manufactured TiO2 and SiO2 nanopowders

International audienceThe development, manufacturing and commercialization of nanomaterials require traceable characterisation processes for quality control and safety of both the exposed workers and final customers. Even if the production batches are considered to be compliant with the industrial applications intended by manufacturers, it is necessary to study the reproducibility of the manufacturing process of nanomaterials independently, so as to determine the variability of key physico-chemical properties of nano-objects from one batch to another.In this study, a metrological approach was employed, using different traceable analytical techniques (X-Ray Diffraction, Transmission Electron Microscopy, Nitrogen physisorption with Brunauer–Emmett–Teller method, X-Ray Fluorescence, Scanning Mobility Particle Sizer and Aerodynamic Particle Sizer) to develop robust, reproducible and statistical methods to evaluate the impact of batch variability on physico-chemical properties of manufactured titanium dioxide and silicon dioxide nano-powders (crystalline structure, crystallite size, primary particle size, specific surface area, chemical composition and the dustiness of nanopowders).Five references of manufactured titanium dioxide nanoparticles and silicon dioxide nanoparticles were characterized with the developed measurement protocols. The reproducibilities of five batches by reference were overall inferior to 10% for crystalline structures, primary particle sizes, specific surface areas and the chemical composition of major components (TiO2 and SiO2) of the nanopowders studied (k = 1). As for the size distributions of released particles from dustiness tests, reproducibility for the modal and mean diameters ranged between 2% and 27%. Moreover, a large variation of nanopowder dustiness was obtained for the same material type (TiO2 or SiO2). This could point out that the physico-chemical properties of nanopowders, linked to the manufacturing process, have a strong impact on the dustiness parameter

Release of Nano-objects, their aggregates and agglomerates from Masks: ambitions and scientific objectives of the RENAAME project

Le contexte pandémique a mis en avant la nécessité de disposer de masques (chirurgicaux, de protection respiratoire FFPx et à usage non sanitaire). Pour la fabrication de ces différents types de masques, l&#8217;ajout de nanomatériaux représente une voie majeure d&#8217;innovation mais est aussi source de préoccupation sanitaire en lien avec une possible exposition par inhalation aux nano-objets, leurs agrégats et agglomérats (NOAA). Ainsi, plusieurs produits commerciaux déclarant des propriétés biocides/virucides ont soulevé diverses interrogations au niveau national [1] et international [2] quant à leur innocuité, aboutissant à leur retrait dès la mise sur le marché. Plus récemment, la présence de NOAA de TiO2 dans des masques a été démontrée [3] alors qu&#8217;aucune mention n&#8217;était précisée sur leurs emballages. Ce sujet de préoccupation relativement émergent souffre cependant d&#8217;un manque de développement méthodologique en ce qui concerne l&#8217;évaluation de l&#8217;exposition par inhalation aux NOAA lors de l&#8217;utilisation de masques. Le projet RENAAME vise à développer une méthodologie d&#8217;évaluation du relargage potentiel en phase aérosol des nanomatériaux déclarés ou impliqués sans indication commerciale dans la fabrication de masques afin d&#8217;évaluer l&#8217;exposition par inhalation dans des conditions réalistes d&#8217;utilisation. L&#8217;originalité du projet RENAAME consiste à développer et valider une approche couplant analyse des matériaux constitutifs des masques et des aérosols potentiellement émis. Si des travaux prénormatifs sont en cours (ISO/TC229 et ISO/NP TS11353) sur ce sujet, le nombre d&#8217;études scientifiques dédiées s&#8217;avère très limité. La méthodologie proposée vise à quantifier la fraction mobilisable (FM) de NOAA dans les masques puis à caractériser la fraction relarguée (FR) en phase aérosol pour des conditions représentatives d&#8217;utilisation. Cette évaluation sera menée sur des masques déclarant commercialement la présence de nanomatériaux présentant un potentiel risque sanitaire (dans le cas de ce projet NOAA composés de TiO2 et d&#8217;Ag), mais également sur des masques ne mentionnant aucune utilisation explicite de NOAA. La détermination de ces deux fractions permettra in-fine d&#8217;aboutir à un classement des différents types de masques en fonction de leur pouvoir émissif (PE=FR/FM). L&#8217;objectif de cette communication est de présenter les actions visées dans le projet RENAAME ainsi que la méthodologie expérimentale associée et les étapes nécessaires à sa qualification et sa validation. Les premiers résultats, en ce qui concerne l&#8217;identification par spectroscopie de fluorescence des rayons X (XRF), la quantification par spectrométrie de masse/d&#8217;émission atomique de plasma à couplage inductif (ICP-MS/OES) et l&#8217;analyse dimensionnelle par microscopie électronique (MEB/MET) de NOAA potentiellement présents, seront présentés. Ce projet est financé par le Programme National de Recherche Environnement Santé-Travail de l&#8217;ANSES avec le soutien des ministères chargés de l&#8217;environnement, de l&#8217;agriculture et du travail (ANSES-22-EST-023). [1] https://www.anses.fr/fr/system/files/CONSO2021SA0089.pdf [2] https://recalls-rappels.canada.ca/fr/avis-rappel/masques-contenant-du-gr&#8230; [3] https://doi.org/10.1038/s41598-022-06605-w</p