Tenax TA Research Articles

Diagnosis of Lung Cancer Through Exhaled Breath: A Comprehensive Study.

Exhaled breath analysis is an attractive lung cancer diagnostic tool. However, various factors that are not related to the disease status, comorbidities, and other diseases must be considered to obtain a reliable diagnostic model. Exhaled breath samples from 646 individuals including 273 patients with lung cancer (LC), 90 patients with cancer of other localizations (OC), 150 patients with noncancer lung diseases (NLD), and 133 healthy controls (HC) were analyzed using gas chromatography-mass spectrometry (GC-MS). The samples were collected in Tedlar bags. Volatile organic compounds (VOCs) were preconcentrated on Tenax TA sorbent tubes with subsequent two-stage thermal desorption followed by GC-MS analysis. The influence of age, gender, smoking status, time since last food consumption, and comorbidities on exhaled breath were evaluated. Also, the effect of histology, TNM, tumor localization, treatment status, and the presence of a tumor on VOC profile of patients with lung cancer were assessed. Intergroup statistics were estimated, diagnostic models were created using artificial neural networks (ANNs) and gradient boosted decision trees (GBDTs). Smoking status and food consumption affect exhaled breath VOC profile: benzene, ethylbenzene, toluene, 1,3-pentadiene 1,4-pentadiene acetonitrile, and some ratios are significantly different in exhaled breath of smokers and nonsmokers; the ratios 2,3-butandione/2-pentanone, 2,3-butandione/dimethylsulfide, and 2-butanone/2-pentanone are affected by time since last food consumption. Exhaled breath of LC is affected by the form of the disease and comorbidities. One-pentanol and 2-butanone were different in exhaled breath of patients with various tumor localization; 2-butanone was different in exhaled breath of patients before and during treatment. Diabetes as a comorbidity affects the pentanal level in exhaled breath; obesity affects the ratios of 2,3-butanedione/dimethylsulfide and 2-butanone/isoprene. Sensitivity and specificity of diagnostic models aimed to discriminate LC and HC, OC, and NLD were 78.7% and 51.0%, 62.2% and 53.4%, and 60.4% and 58.0%, respectively. HC and patients, regardless of the disease, can be classified with sensitivity of 76.6% and specificity of 68.2%. The models created to diagnose lung cancer can also classify OC and NLD as patients with lung cancer. Additionally, the influence of comorbidities and factors not related to the disease status must be considered before the creation of diagnostic models to avoid false results.

Failure of the three-way catalyst (TWC) introduces “super emitters”

Vehicle exhaust is one of the major organic sources in urban areas. Old taxis equipped with failed three-way catalysts (TWCs) have been regarded as “super emitters”. Compressed natural gas (CNG) is a regular substitution fuel for gasoline in taxis. The relative effect of fuel substitution and TWC failure has not been thoroughly investigated. In this work, vehicle exhausts from gasoline and CNG taxis with optimally functioning and malfunctioning TWCs are sampled by Tenax TA tubes and then analyzed by a comprehensive two-dimensional gas chromatography-mass spectrometer (GC×GC–MS). A total of 216 organics are quantified, including 80 volatile organic compounds (VOCs) and 132 intermediate volatility organic compounds (IVOCs). Failure of TWC introduces super emitters with 30 – 70 times emission factors (EFs), 60 – 112 times ozone formation potentials (OFPs), and 34 – 92 times secondary organic aerosols (SOAs) more than normal vehicles. Specifically, for the taxi with failed TWC, the total organic EF of CNG is 16 times that of gasoline, indicating that the failure of TWC exceeds the emission reduction achieved by CNG-gasoline substitution. A significant but unbalanced reduction of ozone and SOA is observed after TWC, whereas a notable “enrichment” in IVOCs was observed. Naphthalene is a typical IVOC component strongly associated with CNG-gasoline substitution and TWC failure, which is lacking in current VOC measurement. We especially emphasize that there is an urgent need to scrap vehicles with failed TWCs in order to significantly reduce air pollution.

Emission characteristics of volatile organic compounds from consumer spray products based on product type, spray method, and distance

Consumer spray products (CSPs) are widely used in daily life, yet it is challenging to find products that fully disclose all components posing health risks. Existing studies primarily focus on product components or VOC quantities emitted during use. Therefore, this study aimed to measure the VOC concentrations emitted by CSPs at varying distances. 47 CSPs available in the Korean market were selected, spanning three spray groups: antiseptics/insecticides (11), aromatic deodorants (16), and coating/polishing agents (20). VOC in air samples were collected using Tenax TA tube at a distance of 1 and 3 m from the sprayed CSPs and then analyzed by thermal desorption–gas chromatography–mass spectrometry system. Discrepancies were found between labeled and actual product components. Aromatic deodorants exhibited the highest total VOCs (TVOCs), while antiseptic/insecticide sprays exhibited the lowest. In the antiseptic/insecticide group and coating/polishing agent group, benzene as a propellant had a maximum concentration (30.9 ± 25.6 ppb), and as trigger, its concentration was 33.7 ± 30.7 ppb. Quantitative analysis using advanced analytical instruments only explained 26.1 ± 20.4% of toluene-equivalent TVOCs, suggesting the presence of additional substances. Concentrations varied by distance due to substance volatility and usage. Maintaining a distance of at least 1 m from CSPs is recommended.

Investigation of indoor air quality in painting studios and health risk assessment

ABSTRACT Indoor pollutants risk the health of people who spend about 90% of their time indoors. Studies have shown that volatile organic compounds (VOCs), which are among these pollutants, can cause asthma and allergies as well as various types of cancer. This study aimed to evaluate the indoor air quality of painting studios and determine the health risk factors for human health. In the survey conducted for 6 weeks, indoor pollutants were measured for three painting studios. In addition, VOC types were determined by Thermal Desorber-Gas Chromatography (TD-GC-MS) analysis in the samples taken on Tenax TA sorbent by active sampling method. The results showed that TVOC and CO₂ values indoors are up to 1.5 and 2.2 times higher than outdoors, respectively. The total cancer risk was found to be higher than the acceptable limit, with a value of 1.60E–06.

A fast thermal desorption unit for micro thermal desorption tubes, Part I: Development of the system and proof of concept measurements with hyper-fast gas chromatography

A system consisting of a thermal desorption unit (TDU) and micro thermal desorption tubes (μTD-tubes, 1.4 mm I.D., 10mg Tenax TA) for fast desorption of analytes was developed for the efficient combination of hyper fast gas chromatography with thermal desorption. The fast desorption is achieved by a significantly reduced thermal mass compared to conventional thermal desorption tubes. Therefore, extremely fast heating and cooling cycles are possible. Proof of concept measurements combining the new setup with a flow-field thermal gradient gas chromatograph (FF-TG-GC) and FID detection show good precision and linearity with R2≥0.995 in the analysis of an n-alkane mix (C8-C20). Thermal desorption occurs within 12s. The impact of reduced μTD-tube dimensions on desorption time, full width at half maximum (FWHM), breakthrough volumes, tube flow rates ergo linear velocities, porosity and back pressure is discussed.

Determination of emission factors from a landfill through an inverse methodology: Experimental determination of ambient air concentrations and use of numerical modelling

The application of numeric modelling for determining the impact of landfills needs for reliable emission source data. In this study, a methodology for the characterization of the emission profiles of the different sources present in landfills for emission factors determination, applying an indirect methodology, is presented. Ambient air concentrations of volatile organic compounds (VOCs), hydrogen sulphide (H2S) and ammonia (NH3) were determined in three potentially emission sources in Can Mata landfill (Hostalets de Pierola, Catalonia, Spain): dumping areas, pre-closed zone and leachate reservoir as well as in biogas, for the determination of emission factors. Multi-sorbent bed and Tenax TA tubes were used for a wide range of VOCs sampling, and analysis was conducted through TD-GC/MS. H2S and NH3 were sampled and analysed using Radiello passive samplers. The highest total VOC (TVOC) concentrations were found in dumping areas (0.7–3.5 mg m−3), followed by leachate reservoir (0.3–0.6 mg m−3) and pre-closed area (77–165 μg m−3). On the other hand, the highest H2S and NH3 concentrations were found in leachate reservoir, presenting values of 0.8–1.1 mg m−3 and 1.7–1.8 mg m−3, respectively. With the application of odour thresholds to the concentrations obtained, the most critical compounds regarding odour annoyances were determined. The highest odour units (O.U.) were found in leachate reservoir due to H2S concentrations, whereas VOCs contributed mainly to O.U. in the dumping areas. The obtained ambient air concentrations were used for the indirect determination of the emission factors through numerical modelling using a Eulerian dispersion model. The emission factors obtained for the landfill for TVOC, H2S and NH3 were in the range of 0.44–10.9 g s-1, 0.16–1.02 g s−1 and 0.23–1.82 g s−1, respectively, depending on the emission source. Reliable emission factors are crucial to obtain landfill impact maps, which are essential for the correct management of these facilities.

Analysis of volatile organic compounds in Korean-bred strawberries: insights for improving fruit flavor.

The strawberry industry in South Korea has witnessed a significant 65% growth over the past decade, surpassing other fruits and vegetables in production value. While sweetness and acidity are well-recognized flavor determinants, the role of volatile organic compounds (VOCs) in defining the desirable flavor profiles of strawberries is also crucial. However, existing research has predominantly concentrated on a limited range of commercial cultivars, neglecting the broader spectrum of strawberry varieties. This study embarked on developing a comprehensive VOC database for a diverse array of strawberry cultivars sourced both domestically and internationally. A total of 61 different strawberry cultivars from Korea (45), the USA (7), Japan (8), and France (1) were analyzed for their VOC content using Tenax TA Thermo Desorption tubes and Gas Chromatography-Mass Spectrometry (GC-MS). In addition to VOC profiling, heritability was assessed using one-way ANOVA to compare means among multiple groups, providing insights into the genetic basis of flavor differences. The analysis identified 122 compounds categorized into esters, alcohols, terpenes, and lactones, with esters constituting the majority (46.5%) of total VOCs in Korean cultivars. 'Arihyang', 'Sunnyberry', and 'Kingsberry' exhibited the highest diversity of VOCs detected (97 types), whereas 'Seolhong' showed the highest overall concentration (57.5mg·kg-1 FW). Compared to the USA cultivars, which were abundant in γ-decalactone (a peach-like fruity aroma), most domestic cultivars lacked this compound. Notably, 'Misohyang' displayed a high γ-decalactone content, highlighting its potential as breeding germplasm to improve flavor in Korean strawberries. The findings underscore the importance of a comprehensive VOC analysis across different strawberry cultivars to understand flavor composition. The significant variation in VOC content among the cultivars examined opens avenues for targeted breeding strategies. By leveraging the distinct VOC profiles, particularly the presence of γ-decalactone, breeders can develop new strawberry varieties with enhanced flavor profiles, catering to consumer preferences for both domestic and international markets.

Effect of spraying air freshener on particulate and volatile organic compounds in vehicles

People in these days spend approximately 6 % of their time in a means of transport. Air fresheners are frequently used in vehicles to mask odors; however, they can cause adverse health effects such as cardiovascular disease, systemic inflammation and autonomic dysfunction. This study aimed to identify the effects of air fresheners on the concentrations of particulate and volatile organic compounds (VOCs) in different vehicle cabins. Scanning mobility and optical particle sizers were used for the particle measurements. VOCs (e.g., BTEX and d-limonene) were collected using a Tenax TA. The products were sprayed for less than a minute. The study assessed three spray products (all trigger types), vehicle size (small, medium, and large), cabin temperature (10 °C, 20 °C, and 25 °C), and in-vehicle ventilation mode (all-off, recirculation, and external inflow modes). The particle concentration increased rapidly during the 1-min spraying of the products. The proportion of nanoparticles in the front seat (67.2 % ± 2.2 %) was 11.1 % ± 2.2 % lower than that in the rear seat (75.6 % ± 2.1 %). The spray product and vehicle size did not significantly affect the particle or VOC concentrations. With an increase in the temperature of the front seat, the proportion of nanoparticles increased by 25.3 % ± 3.2 %. Moreover, the maximum total VOC concentrations (front seat: 364.3 μg/m3; back seat: 241.3 μg/m3) were observed at 20 °C. Under in-vehicle ventilation, recirculation effectively reduced the overall particle concentration within the cabin; however, the generated VOCs circulated. The external inflow proved effective in cabin air purification by reducing the total VOC concentration to 56.0–57.2 % compared with other ventilation modes. These findings provide substantial insight into the persistence of particles and the dynamics of their dispersion, thereby enabling informed decision-making for particle-related risk management.

Measurements of atmospheric C10–C15 biogenic volatile organic compounds (BVOCs) with sorbent tubes

Abstract. Biogenic volatile organic compounds (BVOCs; e.g. terpenes) are highly reactive compounds typically present at sub-parts-per-billion mole fractions in the air. Due to this, their measurements are challenging and they may suffer losses during sampling, storage and analyses. Even though online measurements of BVOCs are becoming more common, the use of sorbent tubes is expected to continue because they offer greater spatial coverage compared to online measurements, and no infrastructure (e.g. electricity, housing/shelter with stable temperature and humidity, sampling lines) is required for sampling. In this study, the performance of an offline technique for the measurement of BVOCs based on sorbent tube sampling was evaluated. Tested compounds included eight monoterpenes, five sesquiterpenes and five oxygenated BVOCs, which are generally either directly emitted (1,8-cineol, linalool, bornyl acetate) or oxidation products (nopinone and 4-acetyl-1-methylcyclohexene). Two sorbent materials (Tenax TA and Carbopack B) and four tube materials (stainless steel (SS), SilcoNert 1000, glass and glass-coated SS) were used. The laboratory evaluations determined the storage stability, breakthrough volumes, suitable tube materials, recovery from ozone scrubbers and particulate filters, and sampling efficiency. In addition, an intercomparison between two laboratories was conducted. No multibed configurations were tested. Of the sorbent materials Tenax TA showed acceptable results for these BVOCs, while with Carbopack B losses and increases in some compounds were detected. Studied compounds were found to be stable in Tenax TA tubes for at least 1 month at −20 and at +20 ∘C. Breakthrough tests indicated that α- and β-pinene have clearly lower breakthrough volumes in the Tenax TA tubes used (4–7 and 8–26 L, respectively) than other terpenes (> 160 L). SS, SilcoNert 1000 and glass were all shown to be suitable tube materials. Results from Tenax TA sorbent tube sampling agreed with online sampling for most compounds. Heated SS tubes, sodium thiosulfate filters and KI/Cu traps were found to be suitable ozone scrubbers for the studied BVOCs. Tested particle filters had a greater impact on limonene (relative difference < +7 %) than on α- and β-pinene (relative difference ±2 %). The laboratory intercomparison of α- and β-pinene measurements showed that in general, measured values by the two laboratories were in good agreement with Tenax TA.

Impact of thermal desorption tubes on the variability of exhaled breath data

Due to the overall low abundance of volatile compounds in exhaled breath, it is necessary to preconcentrate the sample prior to traditional thermal desorption (TD) gas chromatography mass spectrometry analysis. While certain aspects of TD tubes, such as volatile storage, have been evaluated, many aspects remain uncharacterized. Two common TD tubes, Tenax TA and Biomonitoring 5TD tubes, were evaluated for background content and flow rate variability. The data illustrate that the Biomonitoring 5TD tubes have the highest number (23) and abundance of background contamination greater than 3x the mean noise when compared to Tenax TA (13) and empty tubes (9). Tentative identifications of the compounds in the background contamination experiment show that greater than 59% (16/27) of the compounds identified have been reported in the breath literature. The data illustrate the TD tube background abundance could account for more than 70% of the chromatographic signal from exhaled breath for these select compounds. Flow rate measurements of 200 Tenax TA and 200 Biomonitoring 5TD tubes show a large range in measured flow rates among the TD tubes (Tenax: 252.9–284.0 ml min−1, 5TD: 220.6–255.1 ml min−1). Finally, TD tubes of each type, Tenax TA and Biomonitoring 5TD, previously established to have high, medium, and low flow rates, show insignificant differences (p > 0.05) among the tubes of different flow rates, using both gas standards and an exhaled breath from a peppermint experiment. Collectively, these results establish overall background compounds attributed to each TD tube type tested. Additionally, while measured flow rate variability is present and plausibly impacts exhaled breath results, the data demonstrate no statistically significant difference was observed between tubes showing high, medium, and low flow rates from two separate sample types.

Synthetic leathers as a possible source of chemicals and odorous substances in indoor environment

Abstract This article deals with volatile organic substances (VOCs) and odours that can be released into the indoor environment from synthetic leathers that are part of upholstered furniture. The primary task of this study was to provide a detailed analysis of selected synthetic leathers and assess their emission characteristics, including odour substances. VOC emissions were determined using the test chamber method (ČSN EN ISO 16000-9) at a temperature of 23°C and a relative humidity of 50%. The emitted compounds were adsorbed by standard stainless steel tubes with Tenax TA sorbent. VOCs were analysed by thermal desorption and gas chromatography with mass spectrometry The properties of odours were tested using a Sniffer 9000 device, which was directly connected to a gas chromatograph with a flame ionization detector. The dominant substances (with the highest concentration) that were emitted by samples of tested synthetic leathers include toluene (118.2 µg·m−3), 1,2-propanediol (46.2 µg·m−3), and limonene (153.0 µg·m−3). Ohio synthetic leather produced the most unpleasantness hedonic tone (-4) from all evaluated materials.

A Compact Monitor for Ethylene and Other Plant-Produced Volatile Organic Compounds for NASA Space Missions.

In this work, we discuss the development of a compact analytical instrument for monitoring ethylene in compact greenhouses utilized by NASA to grow fresh vegetables in space. Traditionally, ethylene measurements are conducted by GC-MS systems. However, in space, they are not applicable due to their bulky size, heavy weight, special carrier gas requirement and high maintenance. Our group developed a compact and robust battery-powered ethylene monitor based on the principles of analytical gas chromatography. The device utilizes purified ambient air as a carrier gas and a metal oxide sensor as a GC detector. Implementation of a CarboWax 20 M packed column from Restek together with a Tenax TA pre-concentrator allowed us to achieve a 20 ppb limit of detection for ethylene. Full automation of measurements and reporting of concentrations was accomplished via the implementation of a Raspberry Pi 4 computer and a 7″ 720P LED capacitive touchscreen utilized for data output. Based on a feasibility study, a fully automated, industrial-grade ethylene monitoring and removal system for greenhouses was developed.

Volatile anticancer drug determination by thermal desorption technique with polydimethylsiloxane-coated macroporous silica adsorbent in gas chromatography-mass spectrometry.

An analytical method for quantifying the volatile anticancer drugs ifosfamide (IF) and cyclophosphamide (CP) in air was developed on the basis of thermal desorption (TD)-gas chromatography-mass spectrometry. Polydimethylsiloxane-coated macroporous silica was used as the adsorbent. The extraction tube was prepared by packing 0.2g of adsorbent particles into a glass tube. The extraction and desorption efficiencies of the proposed method were quantitatively investigated in this study. The limits of detection of the proposed method for IF and CP were 3.3ngL-1 at an air sampling volume of 3.0 L (30min). The sensitivity of the proposed method was compared with using a Tenax TA packed tube that is widely used as the extraction medium in TD analysis. Finally, detection of IF and CP that evaporated from aqueous standard solution was investigated.

Addressing new chemicals of emerging concern (CECs) in an indoor office

Indoor pollutants change over time and place. Exposure to hazardous organics is associated with adverse health effects. This work sampled gaseous organics by Tenax TA tubes in two indoor rooms, i.e., an office set as samples, and the room of chassis dynamometer (RCD) set as backgrounds. Compounds are analyzed by a thermal desorption comprehensive two-dimensional gas chromatography-quadrupole mass spectrometer (TD-GC × GC-qMS). Four new chemicals of emerging concern (CECs) are screened in 469 organics quantified. We proposed a three-step pipeline for CECs screening utilizing GC × GC including 1) non-target scanning of organics with convincing molecular structures and quantification results, 2) statistical analysis between samples and backgrounds to extract useful information, and 3) pixel-based property estimation to evaluate the contamination potential of addressed chemicals. New CECs spotted in this work are all intermediate volatility organic compounds (IVOCs), containing mintketone, isolongifolene, β-funebrene, and (5α)-androstane. Mintketone and sesquiterpenes may be derived from the use of volatile chemical products (VCPs), while (5α)-androstane is probably human-emitted. The occurrence and contamination potential of the addressed new CECs are reported for the first time. Non-target scanning and the measurement of IVOCs are of vital importance to get a full glimpse of indoor organics.

Volatile organic compounds in school environments of Hawassa city, Ethiopia and assessment of possible human health risks

Volatile organic compounds (VOCs) have become a major human wellbeing and environmental concern worldwide. However, evidence on VOC concentrations in primary school environments in Africa, including Ethiopia, is scarce. The goal of this research was to examine VOCs in primary schools in Hawassa, Ethiopia, and to evaluate possible health threats. Concentrations of 76 VOCs were investigated in air samples from classrooms and playgrounds of eight primary schools in Hawassa, Ethiopia. Air samples were taken via passive sampling method using Tenax TA as a sorbent and analyzed by using thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS). Highest total VOCs (TVOCs) concentration (83 μg/m3) was observed in the classroom of School 2 followed by the classroom of School 1 (76 μg/m3), while the smallest TVOC concentration, 37 μg/m3 in the playground of School 8. Among the BTEX, toluene was the most dominant in all samples, ranging from 33% in School 4–38% in School 1 of ∑BTEX. I/O ratios of individual VOC in the schools ranged from 0.44 in School 4 to 9.21 in School 2. The highest cumulative cancer risk (CCR × 106) and the total hazard ratio indicator (THRI) values were 126 and 1.58E-01 respectively, in the classroom of School 4. The CCR and THRI values indicated that the exposure of children to the measured concentrations of benzene may have potentially harmful effects.

Impact of breast density on classification of infrared spectroscopy for breath-based breast cancer screening.

e13558 Background: While mammography is currently the standard of care for breast cancer screening, dense breast tissue can significantly degrade results. Alternatively, infrared spectroscopy analysis of breath offers a highly sensitive method for identifying exhaled volatile organic compounds (VOCs), which may circumvent issues with breast density. Methods: Alveolar breath samples were collected onto Tenax TA sorbent tubes using a SohnoXB™ breath sampler. Using four desorb temperatures (75, 150, 225 and 300°C), absorption spectra were measured by infrared cavity ring-down spectroscopy (IR-CRDS), a technique for measuring absorption coefficients due to VOCs in exhaled breath. Missing values in the absorption spectra were backfilled using interpolation, and the spectrum was min-max normalized and quadratic detrended. First and second derivatives of the preprocessed absorption spectra were used as features for a support vector machine machine-learning model. Features were ranked based on minimum redundancy maximum relevance (mRMR). The top 20 ranked features were selected to limit the potential for overfitting and then optimized. Model performance was validated using non-nested leave-one-out cross-validation (LOOCV) and nested LOOCV to provide optimistic and pessimistic results, respectively. Results: Absorption spectra from 111 participants (71 positive, 40 control) were used. Of the positive subjects, 30 had low- and 31 had high-density breast tissue (measures missing for 10). Model performance is outlined. A subgroup analysis compared model performance for subjects with low- and high-density breast tissue for both non-nested and nested LOOCV models. Breast density data was not captured for control subjects thus they were not included in the subgroup analysis. Fisher’s exact test was performed to assess for significant difference between model performance for those with low- vs high-density breast tissue, resulting in a p-value of 1.00. Conclusions: Our results suggest that the classification of alveolar breath using IR-CRDS is a promising technique for the detection of breast cancer that is independent of breast density. Breath analysis may therefore become a new alternative or corroborative to mammography to support clinical decision-making. [Table: see text]

Equilibrium study of benzene, toluene, ethylbenzene, and xylene (BTEX) from gas streams by black pine cones-derived activated carbon

Considering environmental emissions, benzene, toluene, ethylbenzene, and xylene (BTEX) are widely used as raw materials in industrial processes. They also affect humans via inhalation, which must be reduced due to their toxicity before further operation. Notably, the leading technologies have tried to remove BTEX emissions with several methods. Continuous innovation of adsorbents is constantly developing in the adsorption mechanism, which has been developed based on waste biomass. Pinus nigra cones is a lignocellulosic raw material that is fast-growing on various soils and found abundant in nature as a precursor. It may be cheaply found available from some natural product vendors. It was used to prepare activated carbon by chemical activation with phosphoric acid (H3PO4), potassium hydroxide (KOH), sulfuric acid (H2SO4), lithium hydroxide (LiOH), zinc chloride (ZnCl2), sodium hydroxide (NaOH) as the activating agents between at 550–850 °C for 2 h. Fourier transforms infrared spectrometer (FT-IR), thermogravimetric analyzer (TGA), scanning electron microscopy (SEM), and N2 gas adsorption–desorption analyzer were used for KAS-ACs characterization. The high BTEX adsorption capacities by ZnCl2 activated carbons were slightly higher than (SBET: 1849 m2/g for KAS-AC91, and Vtotal: 0.44 cm3/g) others. ANOVA results show a high correlation for the KAS-ACs production with ZnCl2, and there was a statistically significant difference between the mean of Vmicro (cm3/g) with activation temperatures p-values<0.05. The removal capacities at 5 μg/L have been done to evaluate using Tenax TA tubes were 92, 96, 88, and 94.08% for benzene, toluene, ethylbenzene, and xylene, respectively. The maximum adsorption capacity for benzene, toluene, ethylbenzene, and xylene onto the KAS-AC91 in the following order: Xylenes (181 μg/g)>Toluene (206 μg/g)>Benzene (171 μg/g)>Ethylbenzene(201 μg/g). This suggests that the KAS-AC91 is an efficient BTEX adsorbent and represents a promising attempt to enhance BTEX adsorption in indoor air quality.

Comparison of generic Tenax and specialized PAH tubes for monitoring polycyclic aromatic hydrocarbons in the ambient air

The thermal desorption (TD) technique has potential advantages for monitoring polycyclic aromatic hydrocarbons (PAHs) in the air, e.g., no need for sample preparation. This study aims to compare the performance of two types of TD tubes: the generic Tenax TA tube and a proprietary PAH tube specifically designed for PAH sampling. Full calibrations were performed on a TD-gas chromatography/mass spectrometry (GC/MS) system for 16 priority PAHs. Co-located field samples were collected with two tubes at a flow rate of 200 mL/min for 24 h in eight rounds. In the laboratory, blank Tenax and PAH tubes had trace-level PAHs ranging from 0 to 0.35 ng/tube and 0−0.83 ng/tube, respectively, after 2-hr conditioning at 330 °C. The calibration with Tenax tubes showed an average precision of 7.5%, R2 from 0.9959 to 1.0000, and method detection limits (MDLs) from 0.056 to 3.64 ng/m3. The calibration of PAH tubes showed an average precision of 7.5%, R2 from 0.9945 to 1.0000, and MDLs from 0.065 to 5.91 ng/m3. In the field, blank Tenax and PAH tubes had trace PAH levels of 0.01–0.34 ng/tube and 0.01−0.42 ng/tube, respectively. Both tubes had negligible breakthroughs (<4%) and good precisions (<20%). Co-located Tenax and PAH tubes displayed a good agreement for light PAHs (differences mostly <30%) but high uncertainty for heavy PAHs (difference 35−70%). Both tubes are applicable for PAH monitoring, but the proprietary PAH tube does not outperform the generic Tenax TA tube. More work is still needed to improve the sensitivity of TD methods for heavy PAHs, e.g., selecting appropriate sorbents and adopting advanced instruments.

Use of PLE-ATD-GC/MSMS for the Quantification of Airborne Pesticides in Active and Passive Samples and in Dust.

An analytical method coupling pressurized liquid extraction (PLE), pre-concentration by thermal desorption (ATD) and analysis by GC/MSMS was developed for the quantification of pesticides in air and dust near vineyards crops to evaluate potential exposure of residents living near these crops. PLE was done using acetonitrile and extracts were concentrated under fume hood to 1mL. 100μL of the extract was spiked in a Tenax TA tube and internal standards and N-tert-butyldimethylsilyl-N-methyltrifluoroacetamide were added before thermal desorption at 300°C for 30min. GC/MSMS analysis was done in MRM mode and limits of quantification and limits of detection were determined for each matrix (passive air sample, active air sample and dust). The method was applied in the field and shows good sensitivity and accuracy.

Non-target scanning of organics from cooking emissions using comprehensive two-dimensional gas chromatography-mass spectrometer (GC×GC-MS)

Cooking emission is a major source influencing human health and air quality. To elucidate the emission pattern of cooking fumes, gaseous and particulate organics were sampled by Tenax TA desorption tubes and quartz filters, respectively. Organics were analyzed by a comprehensive two-dimensional gas chromatography-quadrupole mass spectrometer (GC × GC-qMS) coupled with a thermal desorption system (TDS). A non-target analysis was conducted identifying 166 (gas-phase) and 349 (particle-phase) compounds emitted from cooking fumes. We propose a four-step identification procedure, containing comparison with standards, homologs identification by selected ion chromatograms (SICs), searching spectrums in the National Institute of Standard Technology (NIST) library, and recognitions of unresolved complex mixtures (UCMs). The identified organics are then quantified or semi-quantified by surrogates in the same chemical class with an uncertainty of 27%. Intermediate volatility organic compounds (IVOCs) are extensively detected accounting for 20.5% and 81.4% of the total mass concentration and emission rates (ERs) in gas- and particle-phase samples. Aldehydes (30.6%) and acids (82.7%) dominate the mass concentration of organics in the gas- and particle-phase, respectively. Our work provides a detailed identification procedure in the non-target analysis and emphasizes the importance of IVOC measurement in cooking emissions.