Cyclone Sampler Research Articles

Influencing factors analysis of infectious SARS-CoV-2 aerosols sampling

Assessing the potential infectivity of airborne viruses is critical for evaluating the risk of their transmission through air. This study investigated the factors influencing the collection of infectious SARS-CoV-2 aerosols using three common aerosol samplers: the impactor sampler AGI-30, the SKC Biosampler, and a cyclone sampler WA-400III. It was found that the sampling process over time significantly impacted the infectivity of SARS-CoV-2 captured in the sampler, and the infectivity loss of different SARS-CoV-2 variants in the process varied. Additionally, adding newborn calf serum in the collection suspension could effectively preserve viral infectivity in the sampler. Further tests conducted under various ventilation occasions indicated that ventilation can reduce the virus concentration in the environment and rapidly clear viral particles after aerosol generation. Although the flow rate of WA-400III is higher, it only could collect higher concentrations of viral RNA instead of live viruses than AGI-30 or SKC Biosampler when aerosol was generated constantly in the environment. After aerosol generation stopped, the WA-400III collected more infectious viruses and viral RNA. This study highlights the impact of the sampling process on captured virus should be assessed and protective agent is needed to preserve viral viability. And it is crucial to select appropriate sampler based on environmental characteristics and research objectives for obtaining optimal results. The AGI-30 and SKC Biosampler are preferable for collecting infectious viruses in environments with high aerosol concentrations, while the cyclone sampler WA-400III is more effective for collecting viral nucleic acids and enriching virus samples in confined spaces with lower viral loads.

Comparison of experimental, empirical, and CFD pressure losses of lab-scale sampling cyclones

Significant efforts remain to be undertaken to achieve efficient separation of particulate matter. Devices widely used for this purpose are cyclone separators. This study investigates the pressure loss phenomena and flow structures within cyclone devices, aiming to elaborate and optimize their performance. Traditional cyclone models: (i) Muschelknautz, (ii) Stairmand, and (iii) PM1 Sharp Cut, are evaluated alongside the innovative vortex limiter cyclone (VL) to distinguish their advantages and limitations. The focus is on describing the relation between pressure loss and flow characteristics of the different cyclones with the same design separation diameter of 1μm. Empirical pressure loss correlations analyze how pressure losses vary within different cyclone devices. It was proven that predictions depend on cyclone size and operational parameters. Computational Fluid Dynamics (CFD) simulations further elucidate pressure loss mechanisms, highlighting the complexities inherent in modeling cyclonic behavior accurately. In conclusion, this study contributes to advancing the understanding of cyclone performance by elucidating the intricate interplay between pressure loss phenomena and flow structures. Such insights hold profound indications for optimizing cyclone separator design and operation in diverse industrial applications.

Global Spore Sampling Project: A global, standardized dataset of airborne fungal DNA

Novel methods for sampling and characterizing biodiversity hold great promise for re-evaluating patterns of life across the planet. The sampling of airborne spores with a cyclone sampler, and the sequencing of their DNA, have been suggested as an efficient and well-calibrated tool for surveying fungal diversity across various environments. Here we present data originating from the Global Spore Sampling Project, comprising 2,768 samples collected during two years at 47 outdoor locations across the world. Each sample represents fungal DNA extracted from 24 m3 of air. We applied a conservative bioinformatics pipeline that filtered out sequences that did not show strong evidence of representing a fungal species. The pipeline yielded 27,954 species-level operational taxonomic units (OTUs). Each OTU is accompanied by a probabilistic taxonomic classification, validated through comparison with expert evaluations. To examine the potential of the data for ecological analyses, we partitioned the variation in species distributions into spatial and seasonal components, showing a strong effect of the annual mean temperature on community composition.

Identifying key environmental factors to model Alt a 1 airborne allergen presence and variation

Fungal spores, commonly found in the atmosphere, can trigger important respiratory disorders. The glycoprotein Alt a 1 is the major allergen present in conidia of the genus Alternaria and has a high clinical relevance for people sensitized to fungi. Exposure to this allergen has been traditionally assessed by aerobiological spore counts, although this does not always offer an accurate estimate of airborne allergen load. This study aims to pinpoint the key factors that explain the presence and variation of Alt a 1 concentration in the atmosphere in order to establish exposure risk periods and improve forecasting models. Alternaria spores were sampled using a Hirst-type volumetric sampler over a five-year period. The allergenic fraction from the bioaerosol was collected using a low-volume cyclone sampler and Alt a 1 quantified by Enzyme-Linked ImmunoSorbent Assay. A cluster analysis was executed in order to group days with similar environmental features and then analyze days with the presence of the allergen in each of them. Subsequently, a quadratic discriminant analysis was performed to evaluate if the selected variables can predict days with high Alt a 1 load. The results indicate that higher temperatures and absolute humidity favor the presence of Alt a 1 in the atmosphere, while time of precipitation is related to days without allergen. Moreover, using the selected parameters, the quadratic discriminant analysis to predict days with allergen showed an accuracy rate between 67 % and 85 %. The mismatch between daily airborne concentration of Alternaria spores and allergen load can be explained by the greater contribution of medium-to-long distance transport of the allergen from the major emission sources as compared with spores. Results highlight the importance of conducting aeroallergen quantification studies together with spore counts to improve the forecasting models of allergy risk, especially for fungal spores.

Detection of severe acute respiratory syndrome coronavirus 2 in bioaerosols using digital droplet polymerase chain reaction and loop-mediated isothermal amplification.

In the present study, we simulated human passive breathing, sampled severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) bioaerosols, and compared the detection ability of quantitative polymerase chain reaction (qPCR), digital droplet polymerase chain reaction (ddPCR), and loop-mediated isothermal amplification (LAMP). The specificity of the primer set for the LAMP-based detection of SARS-CoV-2 was evaluated, and its sensitivity using the detection threshold in the amplification curve plots was determined. Next, we used an aerosol collection environment and collected solutions containing predetermined concentrations of plasmid containing SARS-CoV-2 N gene, which were dispersed into the environment, using a cyclone sampler. Finally, we compared the ability of qPCR, ddPCR, and LAMP in detecting SARS-CoV-2 in aerosols and stock solutions. After sampling, qPCR, LAMP and ddPCR can amplify the micro viral samples exponentially. By comparing the three assays, it was judged from the results that qPCR had a slightly higher detection limit, detecting 102 copies per μL, and therefore could not be used as a test for trace samples. qPCR, LAMP, and ddPCR were able to detect aerosol samples of 101 copies per μL. LAMP was able to qualitatively detect the samples, and ddPCR was able to quantitatively detect samples of this order of magnitude. There were 23.2 that could be used as a quantitative assay. This method can be used in public places or hospitals with limited air circulation to detect aerosol-borne viruses in trace quantities and to provide a rapid early warning.

Strong surface winds in Storm Eunice. Part 1: storm overview and indications of sting jet activity from observations and model data

Strong surface winds in Storm <i>Eunice</i>. Part 1: storm overview and indications of sting jet activity from observations and model data

Comparison of two methods for bioaerosol sampling and characterization in a low-biomass chamber environment

Bioaerosols are emitted from various sources into the indoor environment and can positively and negatively impact human health. Humans are the major source of bioaerosol emissions indoors, specifically for bacteria. However, efficient sampling to guarantee successful downstream analyses can be challenging due to the relatively low bioaerosol concentrations in many indoor spaces and variable susceptibility of bioaerosols to sampling stress. Establishing standard procedures for collecting bacteria in low biomass indoor environments can help advance the field. We compared the performance of two approaches (sampling with a personal environmental monitor (PEM) and a two-stage dry cyclone sampler) to capture the bacterial emission from human participants in a controlled chamber environment. The comparison was based on quantifying the DNA yield and characterizing the bacterial community diversity by metabarcoding of the 16S rRNA gene. We found notable differences in the performance of the samplers. The cyclone sampler collected significantly more DNA and 16S rRNA gene copies including Gram-negative bacteria than the PEM sampler (p < 0.001). The bacterial barcode sequencing revealed a significant difference in the diversity of bacteria captured by the two samplers (p < 0.05), with a higher diversity of Gram-negative bacteria captured by PEM than the cyclone sampler. Overall, this study showed that both sampling approaches efficiently sampled in low biomass indoor environments, however with substantial differences in captured DNA concentrations, bacterial concentrations, and bacterial diversity. Our results indicate that bioaerosol sampler choice is highly research question dependent, and this study provides data support to make informed choices.

Immunomagnetic separation coupled with flow cytometry for the analysis of Legionella pneumophila in aerosols

Legionella pneumophila are pathogenic bacteria that can be found in high concentrations in artificial water systems like evaporative cooling towers, which have been the source of frequent outbreaks in recent years. Since inhaled L. pneumophila can lead to Legionnaires’ disease, the development of suitable sampling and rapid analysis strategies for these bacteria in aerosols is therefore of great relevance. In this work, different concentrations of viable L. pneumophila Sg 1 were nebulized and sampled by the cyclone sampler Coriolis® µ under defined conditions in a bioaerosol chamber. To quantify intact Legionella cells, the collected bioaerosols were subsequently analyzed by immunomagnetic separation coupled with flow cytometry (IMS-FCM) on the platform rqmicro.COUNT. For analytical comparison, measurements with qPCR and cultivation were performed. Limits of detection (LOD) of 2.9 × 103 intact cells m−3 for IMS-FCM and 7.8 × 102 intact cells m−3 for qPCR indicating a comparable sensitivity as in culture (LOD = 1.5 × 103 culturable cells m−3). Over a working range of 103 − 106 cells mL−1, the analysis of nebulized and collected aerosol samples with IMS-FCM and qPCR provides higher recovery rates and more consistent results than by cultivation. Overall, IMS-FCM is a suitable culture-independent method for quantification of L. pneumophila in bioaerosols and is promising for field application due to its simplicity in sample preparation.Graphical abstract

Using qPCR and microscopy to assess the impact of harvesting and weather conditions on the relationship between Alternaria alternata and Alternaria spp. spores in rural and urban atmospheres

Alternaria is a plant pathogen and human allergen. Alternaria alternata is one of the most abundant fungal spores in the air. The purpose of this study was to examine whether Alternaria spp. spore concentrations can be used to predict the abundance and spatio-temporal pattern of A. alternata spores in the air. This was investigated by testing the hypothesis that A. alternata dominates airborne Alternaria spp. spores and varies spatio-temporally. Secondarily, we aimed at investigating the relationship between airborne Alternaria spp. spores and the DNA profile of A. alternata spores between two proximate (~ 7 km apart) sites. These were examined by sampling Alternaria spp. spores using Burkard 7-day and cyclone samplers for the period 2016–2018 at Worcester and Lakeside campuses of the University of Worcester, UK. Daily Alternaria spp. spores from the Burkard traps were identified using optical microscopy whilst A. alternata from the cyclone samples was detected and quantified using quantitative polymerase chain reaction (qPCR). The results showed that either A. alternata or other Alternaria species spores dominate the airborne Alternaria spore concentrations, generally depending on weather conditions. Furthermore, although Alternaria spp. spore concentrations were similar for the two proximate sites, A. alternata spore concentrations significantly varied for those sites and it is highly likely that the airborne samples contained large amounts of small fragments of A. alternata. Overall, the study shows that there is a higher abundance of airborne Alternaria allergen than reported by aerobiological networks and the majority is likely to be from spore and hyphal fragments.

104 Application of CFD Simulation for Development Cyclone Samplers

Abstract Aerosol sampling is one of the largest and growing application areas of small-scale cyclone separators. A series of limit values are already or will be reduced in the future and therefore there is a need for samplers operating at larger flow rates that can collect the required amount of particles for analysis at lower aerosol concentrations. Therefore, the main goal of this work was to develop and validate a Computational Fluid Dynamics (CFD) model that can be used for simulation and optimisation of cyclone samplers. For aerosol flow modelling the Euler-Lagrange method was applied where the continuous phase is treated in an Eulerian manner, whereas the dispersed phase is treated in a Lagrangian approach. For a proper simulation of the flow field, the Large Eddy Simulation (LES) technique was used. A dynamic Smagorinsky-Lilly model was applied to calculate subgrid-scale turbulence. The developed model was validated on two cyclone samplers, a 9.5 mm in diameter sampling cyclone of the HD design and a 23 mm in diameter FSP 10 cyclone. For that, the simulated performance characteristics, such as a cut-size, a slope of the penetration curve, and the pressure drop, were compared with the experimental measurements. The simulation results agree well with experimental data. The deviation in cut-size, the slope of the penetration curve, and the pressure drop between the experimental data and LES simulations of the HD cyclone do not exceed 7%, 18.4%, and 10.3% respectively. Regarding the FSP10 cyclone, the deviations in cyclone performance characteristics are even lower.

83 Development of a New Xrd Method to Evaluate Exposure to Respirable TiO2 in Workplace Air

Abstract ECHA classified TiO2 particles with an aerodynamic diameter ≤10 μm as carcinogen. Although the OELV for TiO2 is still related to inhalable particles in many jurisdictions, NIOSH recommended a REL of 2.4 mg/m3 for fine TiO2, and 0.3 mg/m3 for ultrafine TiO2. The latter implies the development of a more robust method for measuring TiO2 in workplace air. X-ray diffraction (XRD) is a powerful laboratory method for quantifying crystalline matter and is frequently used to measure respirable crystalline silica in workplaces. Rutile and anatase powders were obtained from a commercial vendor and a size fraction smaller than 10 µm was separated from these powders and used to prepare a calibration series in a calm-air dust chamber. The methodology for quantifying the rutile or anatase is performed as described in ISO 16258-1:2015 for measuring respirable crystalline silica. The limit of detection and quantification (LOD/LOQ) were for rutile 0.8/1.4 µg and anatase 0.6/1.1 µg, respectively. From these measurements, we conclude that direct on filter XRD is a powerful method for analyzing respirable TiO2 samples. Further validation of the XRD method was performed by comparing the results of 177 respirable personal samples collected on 25 mm MCE filters using Casella-HD cyclone samplers at nine TiO2 production plants with ICP-MS data gained from the same samples. Excellent correlations were obtained between the XRD and ICP-MS data for each sampling site but observed consistent site-dependent deviations explained by differences in crystallinity of the TiO2 phases and the presence of titanium-containing minerals other than rutile and anatase.

Estimation of particle size distributions in the atmosphere—analysis of Fe and Ca particles as the representative examples

Atmospheric aerosols, including primary aerosols emitted directly into the atmosphere and secondary aerosols generated in the atmosphere from various chemically complex particles, cause a variety of environmental problems such as climate change, photochemical smog formation, and a decrease in incoming solar radiation. Therefore, it is important to understand the causes of aerosol particles and their impact on human society. In particular, particle size is an important indicator of lung penetration depth, aerosol transport, and optical properties. Hence, we mathematically estimated the airborne particle size distributions of each chemical component by collecting aerosol samples from the atmosphere using two types of cyclone samplers, large and small cyclone samplers. This study’s findings also suggest that calculated changes in particle size distribution can reflect changes in particle sources. The higher resolution of the continuous functions will enable the detection of the subtle changes in particle size distributions of each chemical component, which is helpful to understand the temporal changes in the chemical properties of the airborne aerosol particles.

Quiescence of Escherichia coli Aerosols to Survive Mechanical Stress during High-Velocity Collection.

A low cutpoint wetted wall bioaerosol sampling cyclone (LCP-WWC), with an aerosol sampling flow rate of 300 L/min at 55″ H2O pressure drop and a continuous liquid outflow rate of about 0.2 mL/min, was developed by upgrading an existing system. The laboratory strain Escherichia coli MG1655 was aerosolized using a six-jet Collison Nebulizer and collected at high velocity using the LCP-WWC for 10 min with different collection liquids. Each sample was quantitated during a 15-day archiving period after aerosolization for culturable counts (CFUs) and gene copy numbers (GCNs) using microbial plating and whole-cell quantitative polymerase chain (qPCR) reaction. The samples were analyzed for protein composition and antimicrobial resistance using protein gel electrophoresis and disc diffusion susceptibility testing. Aerosolization and collection were followed by an initial period of quiescence or dormancy. After 2 days of archiving at 4 °C and RT, the bacteria exhibited increased culturability and antibiotic resistance (ABR), especially to cell wall inhibitors (ampicillin and cephalothin). The number of resistant bacteria on Day 2 increased nearly four-times compared to the number of cells at the initial time of collection. The mechanical stress of aerosolization and high-velocity sampling likely stunned the cells triggering a response of dormancy, though with continued synthesis of vital proteins for survival. This study shows that an increase in intensity in environmental conditions surrounding airborne bacteria affects their ability to grow and their potential to develop antimicrobial resistance.

London Plane Tree Pollen and Pla A 1 Allergen Concentrations Assessment in Urban Environments

The London plane tree is frequently used in gardens, parks, and avenues in European urban areas for ornamental purposes with the aim to provide shade, and given its tolerance to atmospheric pollution. Nevertheless, unfortunately, over recent decades, bioaerosols such as Platanus pollen grains cause increasing human health problems such as allergies or respiratory tract infections. An aerobiological sampling of airborne Platanus pollen and Pla a 1 allergen was performed using two volumetric traps placed on the roof of the Science Faculty building of the city of Ourense from 2009 to 2020. A volumetric sampler Hirst–type Lanzoni VPPS 2000 (Lanzoni s.r.l. Bologna, Italy) was used for pollen sampling. Pla a 1 aeroallergen was sampled by using a Burkard Multi-Vial Cyclone Sampler (Burkard Manufacturing Co., Ltd., Hertfordshire, UK) and by means of the enzyme-linked immunosorbent assay (ELISA) technique. Data mining algorithms, C5.0 decision trees, and rule-based models were assessed to evaluate the effects of the main meteorological factors in the pollen or allergen concentrations. Plane trees bloom in late winter and spring months in the Northwestern Spain area. Regarding the trends of the parameters that define the Platanus pollen season, the allergen values fitted the concentrations of pollen in the air in most cases. In addition, it was observed that a decrease in maximum temperatures causes a descent in both pollen and allergen concentrations. However, the presence of precipitations only increases the level of allergens. When the risk of allergy symptomatology was jointly assessed for both the concentration of pollen and allergens in the study area, the number of days with moderate and high risk for pollen allergy in sensitive people increased with respect to traditional alerts considering only the pollen values.

Environmental DNA reveals diversity and abundance of Alternaria species in neighbouring heterogeneous landscapes in Worcester, UK

Alternaria is a pathogenic and allergenic fungus affecting 400 plant species and 334 million people globally. This study aimed at assessing the diversity of Alternaria species in airborne samples collected from closely located (7 km apart) and heterogeneous sites (rural, urban and unmanaged grassland) in Worcester and Lakeside, the UK. A secondary objective was to examine how the ITS1 subregion varies from ITS2 in Alternaria species diversity and composition. Airborne spores were collected using Burkard 7-day and multi-vial Cyclone samplers for the period 5 July 2016–9 October 2019. Air samples from the Cyclone were amplified using the ITS1and ITS2 subregions and sequenced using Illumina MiSeq platform whereas those from the Burkard sampler were identified and quantified using optical microscopy. Optical microscopy and eDNA revealed a high abundance of Alternaria in the rural, urban and unmanaged sites. ITS1 and ITS2 detected five and seven different Alternaria species at the three sampling sites, respectively. A. dactylidicola, A. metachromatica and A. infectoria were the most abundant. The rural, urban and unmanaged grassland sites had similar diversity (PERMANOVA) of the species due to similarity in land use and proximity of the sites. Overall, the study showed that heterogeneous and neighbouring sites with similar land uses can have similar Alternaria species. It also demonstrated that an eDNA approach can complement the classical optical microscopy method in providing more precise information on fungal species diversity in an environment for targeted management. Similar studies can be replicated for other allergenic and pathogenic fungi.

An ultrasensitive and rapid “sample-to-answer” microsystem for on-site monitoring of SARS-CoV-2 in aerosols using “in situ” tetra-primer recombinase polymerase amplification

Airborne transmissibility of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has highlighted the urgent need for aerosol monitoring of SARS-CoV-2 to prevent sporadic outbreaks of COVID-19. The inadequate sensitivity of conventional methods and the lack of an on-site detection system limited the practical SARS-CoV-2 monitoring of aerosols in public spaces. We have developed a novel SARS-CoV-2-in-aerosol monitoring system (SIAMs) which consists of multiple portable cyclone samplers for collecting aerosols from several venues and a sensitive “sample-to-answer” microsystem employing an integrated cartridge for the analysis of SARS-CoV-2 in aerosols (iCASA) near the sampling site. By seamlessly combining viral RNA extraction based on a chitosan-modified quartz filter and “in situ” tetra-primer recombinase polymerase amplification (tpRPA) into an integrated microfluidic cartridge, iCASA can provide an ultra-high sensitivity of 20 copies/mL, which is nearly one order of magnitude greater than that of the commercial kit, and a short turnaround time of 25 min. By testing various clinical samples of nasopharyngeal swabs, saliva, and exhaled breath condensates obtained from 23 COVID-19 patients, we demonstrate that the positive rate of our system was 3.3 times higher than those of the conventional method. Combining with multiple portable cyclone samplers, we detected 52.2% (12/23) of the aerosol samples, six times higher than that of the commercial kit, collected from the isolation wards of COVID-19 patients, demonstrating the excellent performance of our system for SARS-CoV-2-in-aerosol monitoring. We envision the broad application of our microsystem in aerosol monitoring for fighting the COVID-19 pandemic.

Airborne Pollen, Allergens, and Proteins: A Comparative Study of Three Sampling Methods

Nowadays, there is a wide range of different methods available for the monitoring of pollen and allergens, but their relative efficiency is sometimes unclear, as conventional pollen monitoring does not thoroughly describe pollen allergenicity. This study aims to evaluate airborne pollen, allergen, and protein levels, associating them with meteorological and chemical parameters. The sampling was performed in Bologna (Italy) during the grass flowering period, with three different devices: a Cyclone sampler (CS), a Dicothomous sampler (DS), and a Berner impactor (BI). Total proteins were extracted from aerosol samples, and grass allergens Phl p 1 and Phl p 5 were quantified by ELISA. Airborne Poaceae pollen concentrations were also evaluated, using a Hirst-type trap. Proteins and allergens collected by CS resulted about ten times higher than those collected by the other two instruments, possibly due to their different cut-offs, while DS and BI results appeared consistent only for the total proteins collected in the fine fraction (1.3 vs. 1.6 μg/m3). Airborne proteins correlated neither with Poaceae pollen nor with its aeroallergens, while aeroallergens correlated with pollen only in the coarse particulate, indicating the presence of pollen-independent aeroallergens in the fine particulate, promoted by high wind speed.

Comparison of the Chemical Characteristics and Toxicity of PM2.5 Collected Using Different Sizes of Cyclones

Cyclone sampling devices have been helpful in assessing the toxic effects of fine particulate matter (PM2.5). The particle collection efficiency of sampling devices is critical. This study investigated the effect of cyclone size on particle size, chemical composition, and particle toxicity. Three cyclones with different inner diameters (12–68 mm) were tested for penetration using an aerodynamic particle sizer, fluorescent polystyrene latex, and a differential mobility analyzer. The elemental and water-soluble ion compositions of the particles collected by different cyclones were compared. An evaluation of the particles’ toxicity was conducted by comparing the results of dithiothreitol (DTT), limulus amebocyte lysate (LAL), and cell exposure assays. The experimental evaluation showed a 50% cut-size of the cyclones between 0.17–0.28, 0.34–0.36, and 0.70 μm for the small, medium, and large cyclones, respectively. To collect PM2.5 and evaluate separation performance in the real environment, the small and large cyclones were selected according to the particle penetration and flow rate. A comparison of chemical composition and enrichment factor values found that the particles in the small cyclone samples contained smaller and more anthropogenic sources than those in the large cyclone samples. The oxidative potential (OP) measured by the DTT assay of the samples collected using the small and large cyclones differed across sampling periods and associated with the transition metals. The viability of human epithelial A549 cells after exposure to the collected particles using the cyclones was different across sampling periods and associated with OP. The endotoxin concentrations measured in the LAL assay were found only in the large cyclone samples; they affected the estimated level of cytokine based on IL(interleukin)-6 release from human leukemia monocytic (THP-1) cells derived macro-phage-like cells. Regardless of the size, the cyclone techniques used in this study to collect aerosol particles would be a powerful tool for a detailed evaluation of particle toxicity.

Development and Testing of the A1 Volumetric Air Sampler, an Automatic Pollen Trap Suitable for Long-Term Monitoring of eDNA Pollen Diversity.

Airborne pollen surveys provide information on various aspects of biodiversity and human health monitoring. Such surveys are typically conducted using the Burkard Multi-Vial Cyclone Sampler, but have to be technically optimized for eDNA barcoding. We here developed and tested a new airborne pollen trap, especially suitable for autonomous eDNA-metabarcoding analyses, called the A1 volumetric air sampler. The trap can sample pollen in 24 different tubes with flexible intervals, allowing it to operate independently in the field for a certain amount of time. We compared the efficiency of the new A1 volumetric air sampler with another automated volumetric spore trap, the Burkard Multi-Vial Cyclone Sampler, which features shorter and fewer sampling intervals to evaluate the comparability of ambient pollen concentrations. In a sterile laboratory environment, we compared trap performances between the automated volumetric air samplers by using pure dry pollen of three species—Fagus sylvatica, Helianthus annuus and Zea mays—which differ both by exine ornamentation and pollen size. The traps had a standard suction flow rate of 16.5 L/min, and we counted the inhaled pollen microscopically after a predefined time interval. Our results showed that though we put three different pollen types in the same container, both the traps inhaled all the pollens in a statistically significant manner irrespective of their size. We found that, on average, both traps inhaled equal an number of pollens for each species. We did not detect any cross-contamination between tubes. We concluded that the A1 volumetric air sampler has the potential to be used for longer and more flexible sampling intervals in the wild, suitable for autonomous monitoring of eDNA pollen diversity.

Determination of Gaseous and Particulate Secondary Amines in the Atmosphere Using Gas Chromatography Coupled with Electron Capture Detection

The aim of this study was to develop and optimize methods for the determination of gaseous and particulate (PM2.5) secondary amines (SAs) in the atmosphere using gas chromatography coupled with electron capture detection (GC-ECD) following chemical derivatization. The methods employed the liquid–liquid extraction (LLE) of pentafluorobenzenesulfonyl derivatives of the SAs before analytical samples were injected into GC-ECD. The optimized methods were applied to the determination of SAs in gaseous and particulate samples at two sites (urban and rural areas) from June to September in 2021. Gaseous samples were collected into an SPE cartridge containing a mixture of silica gel and sulfamic acid at a flow rate of 2 L·min−1 for 48 h. Particulate samples were collected onto 47 mm filters by a cyclone sampler at a flow rate of 16.7 L·min−1 for 48 h. The linearity of calibration curves, accuracy, and precision of the methods were satisfactory. In most of the field samples, dimethylamine (DMA), methylethylamine (MEA), diethylamine (DEA), and dipropylamine (DPA) were found to be the most frequently encountered compounds at the sampling sites.