Analysis of volatile organic compounds in a waste collection centre using multisorbent adsorption and GC/MS thermal desoprtion system

Volatile organic compounds (VOCs) released by waste treatment systems may lead to major impacts such as toxic air levels, discomfort incidents and annoying odours. The main objectives of this work were to identify and quantify selected VOCs, emitted during waste collection and processing, to control exposure hazards. An analytical method, previously developed and validated in our laboratory, for the determination of VOCs within a wide range of volatility and polarity and with variable concentrations was used.Peer ReviewedPostprint (author’s final draft

Continuous monitoring of volatile organic compounds through sensorization. Automatic sampling during pollution/odour/nuisance episodic events

Volatile organic compounds (VOCs) are a highly diverse class of chemical contaminants and between 50 and 300 of them may be found in ambient air. In urbanized areas, VOCs are emitted from industrial activities, as well as from vehicle-related and combustion sources. VOCs outdoors can be detected in a broad range of concentrations, usually varying seasonally. The presence of VOCs at relatively high concentrations has been related to poor air quality, discomfort and odorous nuisances. Additionally, they can have negative health effects to the human organism. Hence, in locations where recurrent sporadic situations of high VOCs levels take place, episodic samples' evaluation is necessary instead of 24 h or longer sampling period's evaluations. The use of commercially available metal oxide semiconductor gas sensors for a continuous monitoring of VOCs concentrations in outdoor air is an interesting and innovative technology. Additionally, the use of these sensors for the activation of a VOCs sampler when episodic events of nuisance/odorous annoyance occur was successfully evaluated. The sensor activation is induced by higher VOCs concentrations from a wide number of VOC chemical families. Two sensor stations, developed at our laboratory and provided with sampling pumps, were located in the municipality of Santa Margarida i els Monjos (Catalunya, Spain) in January 2021. The stations started recording data continuously from two different types of VOCs sensors, temperature, relative humidity and pressure in 1.5-min periods. Automatic VOCs sampling was conducted, using multi-sorbent bed tubes, during the months of June–July when the sensors electronic values exceeded a set point value. Samples were analysed through TD-GC/MS. TVOC concentrations in episode samples ranged between 78-669 and 12–159 µg m-3 in Site 1 and Site 2, respectively. Although TVOC concentrations were not high in all cases, relevant concentrations of chloroform were observed, especially in Site 1, with concentrations ranging from 19 to 159 µg m-3.Postprint (published version

Calidad de aire interior: Filtros de carbón activo para su mejora

norma NTP 989Preprin

Chemical characterization of odorous emissions: A comparative performance study of different sampling methods

A comparison among different sampling methods (3 types of sorbent tubes and polymeric bags) commonly adopted in chemical analyses of odorous emissions was performed. To investigate the different performances, a lignocellulosic biomass storage plant was selected to obtain preliminary information about the chemical nature of odorous emissions. Samples of odorous emissions were collected at different biomass piles and analysed by dynamic olfactometry and TD-GC-MS. By comparing the two adopted sampling methods (tubes and bags), different performances are shown, depending on their specificity. By the comparison among the three types of sorbent tubes (Multi-sorbent bed (Carbotrap, Carbopack X and Carboxen 569), Tenax and Sulphur), Sulphur and Multi-sorbent bed present similar performance, while Tenax TA tubes show a different trend in terms of type and numerosity of detected compounds. In addition, from the comparison between tubes and polymeric bags, the number and types of compounds detected in bags are more comparable to those observed in the Multi-sorbent bed and Sulphur tubes. However, a difference between the two methods appears, especially in the detection of low-molecular weight organic compounds. In this study, it is possible to highlight that, due to the complexity of odorous emissions, the selection of the sampling material may affect the obtained chemical results. The detection of different classes of compounds, is a crucial point, to obtaining the most complete characterization of mixtures and comparing the chemical profile with olfactometric results: care must be taken in the choice of sampling material and procedure.Peer ReviewedPostprint (author's final draft

Comparative of the adsorption performance of a multi-sorbent bed (Carbotrap, Carbopack X, Carboxen 569) and a Tenax TA adsorbent tube for the analysis of volatile organic compounds (VOCs)

A comparison between two types of adsorbent tubes, the commonly used Tenax TA and a multi-sorbent bed (Carbotrap, Carbopack X, Carboxen 569) tube developed in our laboratory, has been done to evaluate their usefulness in the analysis of VOCs in ambient air. Duplicate indoor and outdoor samples of Tenax TA and multi-sorbent tubes of 10, 20, 40, 60 and 90 litres were taken in Barcelona city (Spain) on July and October of 2009. Breakthrough values (defined as %VOCs found in the back tube) were determined for all sampling volumes connecting two sampling tubes in series. The analysis was performed by automatic thermal desorption (ATD) coupled with capillary gas chromatography (GC)/mass spectrometry detector (MSD). Significant differences between the concentrations obtained form multi-sorbent bed and Tenax TA tubes are observed for the very volatile compounds (56ºC<boiling point<100ºC and 4kPa<vapour pressure (20ºC)<47kPa) (e.g. acetone, isopropanol, n-hexane) and for alcohols and chlorinated compounds (e.g. 1-butanol, carbon disulphide, dichloromethane, chloroform, carbon tetrachloride, trichloroethylene, tetrachloroethylene), being the concentrations higher in multi-sorbent bed than in Tenax TA tubes. On the other hand, mainly all compounds with boiling points higher than 100ºC (except α-pinene, chlorinated and polar compounds) do not show significant differences between the obtained multi-sorbent bed and Tenax TA tubes concentrations. For the concentrations obtained, Tenax TA present high breakthrough values (from 0 to 77%) for mainly all compounds and sampling volumes studied. On the other hand, multi-sorbent bed tubes do not exhibit important breakthrough values for these compounds, except the VVOCs ethanol (for all sampled volumes), and acetone, dichloromethane and isopropanol (for sampling volumes over 40 litres). The concentration differences observed between Tenax TA and multi-sorbent bed tubes are directly related to the high breakthrough values determined for Tenax TA adsorbent.Peer ReviewedPostprint (published version

Methodology for determining indoor air quality and identifiying the origin of odour episodes in indoor environments through dynamics VOC sampling and TD-GC/MS analysis

A methodology for identifying volatile organic compounds (VOCs) and determining air quality of indoor air has been developed. The air samples are collected using pump samplers by the inhabitants when they perceive odorous and/or discomfort episodes. Glass multi-sorbent tubes are connected to the pump samplers for the retention of VOC. The analysis is performed by automatic thermal desorption (ATD) coupled with gas chromatography-mass spectrometry (GC/MS). This methodology can be applied in cases of sick building syndrome (SBS) evaluation, in which building occupants experience a series of varied symptoms that appear to be linked to time spent in the building. Chemical pollutants concentrations (e.g., VOC) have been described to contribute to SBS. To exemplify the methodology, a qualitative determination and an evaluation of existing VOC were performed in a dwelling where the occupants experienced the SBS symptoms. Higher total VOC (TVOC) levels were detected during episodes in indoor air (1.33 ± 1.53 mg/m3) compared to outdoor air (0.71 ± 0.46 mg/m3). The concentrations of individual VOCs, such as ethanol, acetone, isopropanol, 1-butanol, acetic acid, acetonitrile and 1-methoxy-2-propanol, were also higher than the expected for a standard dwelling. The external source of VOC was found to be an undeclared activity of storage and manipulation of solvents located at the bottom of a contiguous building.Peer ReviewedPostprint (author’s final draft

Sulphur compounds: comparison of different sorbent tubes for their detection

Different techniques have been developed for the analysis of gaseous sulphur pollutants, to maximize the analytical signals. In a complex matrix, such as odorous emissions, the detection of sulphur compounds can be critical in GC analysis, due to the lower concentration of these pollutants and the disturbing effect of co-eluting hydrocarbons. However, their detection is fundamental because they have a non-negligible odour impact. In the field of gaseous emissions analytics, it is common to use sorbent tubes for the sampling step. This technology uses different adsorbent materials, with different selectivity depending on the nature of the gas to be analysed. This work aims to evaluate the ability of three different sorbent tubes to collect different sulphur compounds, belonging to the classes of mercaptans, thioethers and aromatic heterocyclic compounds. A standard solution of 10 sulphur compounds was prepared by diluting in methanol 50 µL of each liquid standard into a 10 mL flask. Subsequently, this solution was diluted in methanol to obtain sulphur standards at five different concentrations (approximately 5-500 ng/µL). The tubes were loaded with the standard solutions with an aliquot of each solution, using a gas chromatograph packed column injector and subsequently analysed by TD-GC-MS. By the results obtained - average Response Factor (RF) and its Relative Standard Deviation (% RSD), it is possible to conduct a comparison among these tubes and evaluate their performance. From the comparison of the tubes, discussing % RSD, it is possible to highlight a slightly better performance, in terms of the number of compounds with % RSD = 30%, for tubes specific for sulphur compounds. Focusing on RF values, multi-sorbent bed tubes show slightly higher RFs for very volatile sulphur compounds, but Sulphur tubes present higher RF values for 6 compounds out of 10 compounds considered. The performance of Tenax TA tubes, instead, appears strictly correlated with the compound’s volatility and therefore they don’t appear useful for sorption of very volatile compounds.Peer ReviewedPostprint (published version

Identification of volatile organic compounds (VOC) emitted from three European orchid species with different pollination strategies : two deceptive orchids (Himantoglossum robertianum and Ophrys apifera) and a rewarding (Gymnadenia conopsea)

Volatile organic compounds (VOC) emission was evaluated in the inflorescences of three species of the family Orchidaceae: Himantoglossum robertianum, Ophrys apifera and Gymnadenia conopsea, that comprise three different pollination strategies: non-rewarding food deceptive, non-rewarding sexually deceptive and nectar rewarding, respectively. VOC were dynamically sampled in custom packed glass multi-sorbent cartridge tubes (Carbotrap, Carbopack X and Carboxen 569). A modified Tedlar® gas sampling bag was placed in vivo covering the inflorescence of the studied orchid, a design that prevents the dilution of the VOC mixture emitted by the flower. Multi-sorbent bed tubes were analysed through automatic thermal desorption coupled with a capillary gas chromatography/mass spectrometry detector. A total of 106 different VOC were found in the scents emitted by the three different studied orchids. A 54% of these compounds had already been identified in floral scents. Generally, only 3 compounds were highly abundant in each species: α-pinene, β-pinene and limonene in Himantoglossum robertianum; 1-butanol, butyl ether and caryophyllene in Ophrys apifera; and phenethyl acetate, eugenol and benzaldehyde in Gymnadenia conopsea. The employment of the presented methodologyPostprint (published version

Evaluation of Radiello diffusive sampler indicated for thermal desorption for measuring VOCs in ambient air.

- One of the key aspects regarding air monitoring is to determine the suitability of the methodology chosen. -The comparison between validated active air multi-sorbent tubes and Radiello diffusive samplers show no significant differences between the two methodologies for several compounds studied. -For the Radiello passive sampler, relevant differences have not been observed between the sum of two shorter sampling periods (4 days + 3 days) and a longer sampling period (7 days). -The Radiello diffusive sampler provides satisfactory quantitative measurements and is suitable for the determination of several VOCs in ambient air. -Radiello passive sampler coupled with ATD-GC/MS is a simple to use, sensible and cheap method to assess ambient air concentrations of VOCs. -More research has to be done to enhance the results obtained in this study.Peer ReviewedPostprint (published version

Background fish feminization effects in European remote sites

Human activity has spread trace amounts of chemically stable endocrine-disrupting pollutants throughout the biosphere. These compounds have generated a background level of estrogenic activity that needs to be assessed. Fish are adequate sentinels for feminization effects as male specimens are more sensitive than humans to exogenous estrogenic compounds. High mountain lakes, the most distant environments of continental areas, only receive semi-volatile compounds from atmospheric deposition. We analyzed the expression levels of estrogen-regulated genes in male fish from these mountain lakes in Europe. Incipient feminization involving expression of estrogen receptor and zona radiata genes revealed a widespread diffuse estrogenic impact. This effect was correlated with the concentrations of some organochlorine compounds in fish and was consistent with the persistent occurrence of these tropospheric pollutants in the most remote planet regions. These results should be of general concern given the increasing endocrine disruption effects in human populationsPostprint (published version