Sorbent Tubes Research Articles

Measurement of BTEX (benzene, toluene, ethylbenzene and xylene) concentration at gas stations

Background: Fuel stations are one of the major sources of air pollution with volatile organic compounds, especially the four main petrol compounds benzene, toluene, ethylbenzene, and xylene (BTEX). BTEX in gasoline enters the air of gas stations due to high evaporation of gasoline. Therefore, determining the concentration of these compounds in gas stations in crowded and busy cities is one of the important priorities of environmental health, which is doubly important in terms of its negative effects on health. Methods: In this descriptive cross-sectional study, a total of 39 samples were collected from 13 gas stations. Sampling was performed in autumn 2018 in three working shifts (morning, noon, and night). The method NIOSH-1501 (i.e., using charcoal sorbent tubes and SKC pump with a flow rate of 0.2 L/min) was used for sampling the BTEX compounds. The mean difference and correlation of BTEX compounds based on meteorological parameters and the number of nozzles in gas stations were assessed using one-way ANOVA and correlation tests. Results: The mean and standard deviation of benzene, toluene, ethylbenzene, and xylene concentrations in the air of fuel stations were 2.784±1.461, 3.495±1.390, 2.091±0.811, and 1.140±0.419 mg/m3, respectively. The relationship between BTEX compounds and meteorological parameters such as humidity and exposure time is very important. There is a strong correlation between the concentrations of BTEX compounds. The highest correlation was observed between benzene and toluene and the lowest one was observed between benzene and xylene. In this study, no significant relationship was observed between air temperature and concentration of BTEX compounds, but there was a relationship between relative humidity and the concentration of BTEX compounds. Conclusion: The average benzene concentration in the air at the fuel stations was about 5.5 times the standard limit. Authorities should improve fuel quality and reduce its evaporation through engineering measures to overcome the issue.

Application of hydroxyapatite adsorbent packed in needle trap device for sensitive determination of trace levels of phenolic compounds in the air

Hydroxyapatites have been known as high adsorption capacity, inexpensive, and available absorbents. In this study, nano-hydroxyapatite (n-HA) adsorbent was synthesized, characterized, and employed as an efficient absorbent packed inside Needle Trap Device (NTD) as an environmentally friendly technique for sampling and analysis of phenolic compounds (phenol, 2-chlorophenol, o -cresol, and p -cresol) in the air. The effect of important parameters including the carryover, storage capability, repeatability, and reproducibility was investigated by Response Surface Methodology (RSM). The obtained results by the nano-hydroxyapatite packed NTD (nHAP-NTD) showed that the limit of detection and quantification of the studied analytes were in the range of 0.001–0.01 and 0.004–0.023 ng mL −1 , respectively. Also, the storage stability of the studied compounds in the nHAP-NTD was above 98% after 60 days at 4 °C. The finding results indicated a high correlation (R 2 = 0.98) between the proposed method (nHAP-NTD) and the XAD-7 sorbent tube (standard method NIOSH 2546). Finally, the proposed NTD-GC-FID method was successfully used to sample and determine the levels of the phenolic compounds in the real samples. The proposed nHAP-NTD method can be an eco-friendly, reliable, and efficient method for sampling and determination of the phenolic compounds compared to the National Institute for Occupational Safety and Health (NIOSH) method. The proposed graphical abstract .

Measurement of Diacetyl and Related Compounds in Coffee Roasteries and Breweries.

α-Diketones such as diacetyl (2,3-butanedione) and 2,3-pentanedione are generated during the roasting and fermentation of foods and are also used as flavoring compounds. Exposure to these compounds has been associated with obliterative bronchiolitis in workers. We report indoor air concentrations of diacetyl and 2,3-pentanedione, as well as acetoin (3-hydroxy-2-butanone), in several small coffee roasteries and breweries using standard integrated air sampling sorbent tubes followed by gas chromatography tandem mass spectrometry as well as the first use of on-site continuous real-time proton-transfer reaction time-of-flight mass spectrometry (PTR-ToF-MS). Diacetyl and 2,3-pentanedione were detected in most of the sorbent samples at concentrations between 0.02 and 8 ppbv, and in general were higher in coffee roasteries compared with breweries. Three integrated air samples, all from the barista area at one facility, exceeded the NIOSH recommended exposure limit (REL) of 5 ppbv for diacetyl. 2,3-Pentanedione concentrations in these three samples were greater than 50% of its REL, but did not exceed it. Acetoin, a precursor to diacetyl, was also detected at concentrations between 0.03 and 5 ppbv in most sorbent tube samples, with concentrations generally higher in breweries. PTR-ToF-MS measurements exhibited similar trends and provided continuous real-time volatile organic compound data that showed episodic excursions with peak concentrations of diacetyl and 2,3-pentanedione between 15 and 20 ppbv. Examination of the time series data identified specific activities associated with peak diketone emissions, including transfer of freshly roasted coffee beans to the cooling tray, or the opening of a brew kettle. Additional indoor air quality parameters including CO2, NO2, and PM2.5 were also assessed on-site. Airway inflammation was assessed in 19 workers before and after each work shift using online measurements of fractional exhaled nitric oxide (FENO). The pre-shift mean FENO was 3.7 (95% confidence interval: -3.6, 11.0) ppbv higher and the post-shift FENO was 7.1 (-1.9, 16.1) ppbv higher for workers at coffee roasteries compared with breweries. The cross-shift change in FENO was 3.4 (-2.8, 9.6) ppbv higher for workers at coffee roasteries compared with breweries. However, none of these differences were statistically significant, and the cross-shift change in FENO was not statistically different from zero for either group of workers. The findings from this pilot study demonstrate that α-diketones and related compounds are present in the indoor air of both breweries and coffee roasteries and may exceed health protective guidelines in coffee roasteries. Additional studies are required to fully characterize worker exposures in these settings and to identify specific work activities and processes associated with high exposures. Engineering controls, including targeted exhaust ventilation and the use of low-cost sensors, are recommended as an approach to protect workers from exposure to hazardous levels of α-diketones.

Evaluation of Passive Diffusive‐Adsorptive Samplers for Use in Assessing Time‐Varying Indoor Air Impacts Resulting from Vapor Intrusion

AbstractPassive diffusive‐adsorptive samplers are being considered for vapor intrusion (VI) pathway assessment, particularly where multi‐week time‐weighted average concentrations are desired. Recent studies have shown that passive samplers can produce accurate results under well‐controlled steady concentration conditions, and field performance was also demonstrated at several sites. The objective of this study was to examine passive sampler performance in settings with time‐varying indoor air concentrations, through a comparison of passive sampler results to concentrations determined by 24‐h active sorbent tube sampling in a series of multi‐week deployments. Sampling was performed in a well‐instrumented residential building as well as industrial buildings, over periods of time ranging from 1 to 7 weeks. Strong linear correlations were noted between passive and active sampling concentration results for some passive samplers, with passive sampling results being similar to or lower than measured active sampling results by about 50% for those samplers in the residential study and about 25% higher in the industrial building study. Other samplers produced poor agreement. The conclusion from this study is that some passive samplers have great potential for use in multi‐week indoor air quality monitoring. It was further determined that there is need for accepted procedures to validate and calibrate passive samplers for use in the field.

Trietyloamina. Metoda oznaczania w powietrzu na stanowiskach pracy z zastosowaniem chromatografii gazowej z detekcją płomieniowo-jonizacyjną

Triethylamine (TEA) is a tertiary aliphatic amine. At room temperature it is a colourless liquid with a strong ammonia odor. TEA is used as a substrat in production of quaternary ammonium compound, as a catalyst in polymerization process, as a solvent in organic synthesis and as an emulsifier in the production of dyes and pesticides. Occupational exposure to TEA can cause many adverse effects like skin, respiratory tract or eye irritation. TEA may cause also vision disorder like blurred vision or red-blue vision. The aim of this study was to develop and validate a method for determining TEA in workplace air. The developed method is based on the collection of TEA on sorbent tube filed with two sections of silica gel coated with hydrochloric acid. Silica gel is extracted with methanol:water mixture and resulted solution is analysed with capillary gas chromatography with flame-ionization detector. The study was performed using gas chromatograph equipped with DB-5ms column. The developed method is linear in the concentration range of 7.5–150 μg/ml, which is equivalent to the range of 0.03–6 mg/m3 for 100-L air sample. The analytical method described in this paper makes it possible to determine TEA in workplace air in the presence of other substances. The method is precise, accurate and it meets the criteria for procedures for determining chemical agents listed in Standard No. PN-EN 482. The developed method for determining TEA in workplace air has been recorded as an analytical procedure (see Appendix). This article discusses the problems of occupational safety and health, which are covered by health sciences and environmental engineering.

Determination of 1,3-Butadiene Migrated from Butadiene-Based Polymers to Air and Water Using Sorbent Tubes and Purge-and-Trap

Determination of 1,3-Butadiene Migrated from Butadiene-Based Polymers to Air and Water Using Sorbent Tubes and Purge-and-Trap

Promises of a new versatile field-deployable sorbent tube thermodesorber by application to BTEX analysis in CH4

Characterizing trace compounds in gaseous matrices such as natural gas is challenging owing to the low concentrations and the intricate interactions between compounds and matrices present. In contrast to whole gas sampling methods, direct in situ gas sampling with preconcentration of trace compounds on adsorbent tubes followed by thermal desorption and gas chromatography coupled to mass spectrometry (TD-GC–MS) is a powerful method enabling to screen unknown and targeted trace compounds with low detection limits and where moreover sample transfer and associated loss and contamination risks are avoided. Here, a new versatile, field-deployable thermodesorber prototype (‘nCx-TD’, nCx Instrumentation, Garlin, France) fitted with self-assembled purpose-built Tenax TA adsorbent tubes is presented. Its desorption and GC-injection performances are investigated using a 10 ppmv BTEX in CH4 synthetic gas and by contrasting the results to those obtained by solid phase microextraction (SPME) and direct injection of the synthetic gas. Unlike most commercial thermodesorbers, the nCx-TD is characterized by a fast “plug” injection without re-focusing trap, leading to high chromatographic peak resolutions. Between the closely eluting ethylbenzene and m- and p-xylene isomers, the Gaussian resolution obtained at a concentration of 10 ppmv with the nCx-TD was 2.9 while that obtained by SPME and direct injection was respectively 1.7 and 1.9. The nCx-TD-obtained peak resolutions increased significantly with the concentration (1 to 10 ppmv) while the SPME- and direct injection resolutions remained at a low constant level across concentrations tested. A real natural gas sample was sampled through the Tenax TA adsorbent tubes and analyzed via TD-GC–MS using the nCx-TD. More than 50 distinct trace compounds were detected, opening exciting perspectives of adsorbent tube multibed configurations and direct in situ field sampling on adsorbent tubes with in situ analysis through the nCx-TD and field-portable GC's.

Stability of volatile organic compounds in sorbent tubes following SARS-CoV-2 inactivation procedures

COVID-19 is a highly transmissible respiratory illness that has rapidly spread all over the world causing more than 115 million cases and 2.5 million deaths. Most epidemiological projections estimate that the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) virus causing the infection will circulate in the next few years and raise enormous economic and social issues. COVID-19 has a dramatic impact on health care systems and patient management, and is delaying or stopping breath research activities due to the risk of infection to the operators following contact with patients, potentially infected samples or contaminated equipment. In this scenario, we investigated whether virus inactivation procedures, based on a thermal treatment (60 °C for 1 h) or storage of tubes at room temperature for 72 h, could be used to allow the routine breath analysis workflow to carry on with an optimal level of safety during the pandemic. Tests were carried out using dry and humid gaseous samples containing about 100 representative chemicals found in exhaled breath and ambient air. Samples were collected in commercially available sorbent tubes, i.e. Tenax GR and a combination of Tenax TA, Carbograph 1TD and Carboxen 1003. Our results showed that all compounds were stable at room temperature up to 72 h and that sample humidity was the key factor affecting the stability of the compounds upon thermal treatment. Tenax GR-based sorbent tubes were less impacted by the thermal treatment, showing variations in the range 20%–30% for most target analytes. A significant loss of aldehydes and sulphur compounds was observed using carbon molecular sieve-based tubes. In this case, a dry purge step before inactivation at 60 °C significantly reduced the loss of the target analytes, whose variations were comparable to the method variability. Finally, a breath analysis workflow including a SARS-CoV-2 inactivation treatment is proposed.

Characterization of Naturally Occurring Alpha-Diketone Emissions and Exposures at a Coffee Roasting Facility and Associated Retail Café.

Alpha-diketones such as diacetyl and 2,3-pentanedione have been used as artificial flavorings in a variety of industries and are produced naturally when food products such as coffee beans are roasted. Exposure to these compounds has been associated with bronchiolitis obliterans, a rare and severe respiratory disease. In the current paper, we (i) evaluate which steps in the coffee production process are associated with the highest alpha-diketone emissions at a small craft coffee roaster and associated café, (ii) determine the extent to which direct-reading measurements of CO, CO2, and total volatile organic compounds (VOCs) can serve as lower-cost surrogate indicators for diacetyl concentrations, and (iii) conduct a limited emissions study to quantify the effect that the process variable of roast type has on diacetyl emissions from grinding beans. Exposure and area concentration data for diacetyl and 2,3-pentanedione were collected over 4 days of sampling at a single coffee roaster and associated café. Additional measurements of café patrons' exposure to diacetyl were collected in seven other craft roastery/cafes in Seattle, WA. For the emissions experiments, integrated area air samples for diacetyl were collected using sorbent tubes over 30-min intervals for each roast type with the sorbent tubes positioned next to a grinder placed in an exposure chamber. Sorbent tubes were analyzed for alpha-diketones using gas chromatography-mass spectrometry. A photoionization detector (PID) was also used to measure continuous total VOC concentrations at the coffee roastery, and during each grinding experiment. Diacetyl concentrations in five of the seven personal samples from the craft roastery were above the United States National Institute of Occupational Safety and Health (NIOSH) Recommended Exposure Limit (REL) of 5 ppb as an 8-h time-weighted average (TWA)-and one of the seven personal samples exceeded the NIOSH REL for 2,3-pentanedione-9.3 ppb as an 8-h TWA. Median diacetyl and 2,3-pentanedione emissions were highest at the bagging machine followed by the grinder, roaster, barista, and background areas. The arithmetic mean diacetyl concentrations from the seven personal samples collected from café patrons was 3.96 ppb, suggesting that diacetyl exposure poses a negligible health risk to café patrons. Correlations between diacetyl and total VOCs, CO, and CO2 showed that diacetyl was well correlated with total VOCs, but poorly correlated with CO and CO2. Based on our limited emissions study, French roast was associated with the highest mass emission factor of diacetyl. Results from the exposure assessment study indicated that coffee production workers at this facility had elevated exposures to diacetyl and 2,3-pentanedione compared to recommended guidelines, whereas baristas and café patrons received lower exposures. Area sampling showed that the areas with the highest alpha-diketone emissions were the grinder and the bagging machine, which are both areas associated with tasks involving ground roasted coffee. Future research could focus on designing and evaluating effective engineering controls, in the form of local exhaust ventilation, with the goal of reducing alpha diketone exposures, as well as conducting similar studies at other small-scale craft coffee roasters and cafés to better understand the variability in these emissions and exposures within these types of facilities.

Comparison of automated mixer-assisted mini-scale liquid-liquid extraction coupled with full evaporation dynamic headspace extraction with United States Environmental Protection Agency methods for the gas chromatography-mass spectrometric analysis of chlorinated benzenes

Three modes of facilitating mini-scale-liquid-liquid-extraction (msLLE) prior to automated integration with full evaporation dynamic headspace (FEDHS) extraction were evaluated in this work. For msLLE, 1.2 mL of dichloromethane (DCM) was added to a conical-bottomed vial containing 7 mL of aqueous sample. The solution was then subjected to three different mixing modes, namely vortex-assistance (where a “whirlpool” was created in the solution), agitation-assistance (where the vial was rotated in circular motion) and quickMix-assistance (where the vial was shaken at a high speed). Vortex-assistance was performed manually while the other two modes were automated using a commercial autosampler. Following this, the DCM extract was transferred automatically to another vial and was then vaporized and sent through a Tenax TA sorbent tube in the FEDHS step. Due to the stronger π interaction between the sorbent and the analytes of interest, the analytes were selectively concentrated while the DCM vapor passed through unhampered. After FEDHS, the analytes were thoroughly desorbed into a gas chromatography-mass spectrometric system for analysis. The applicability of this procedure was validated in the extraction of six chlorinated benzenes (CBs) (1,2-dichlorobenzene, 1,3-dichlorobenzene, 1,4-dichlorobenzene, 1,2,4-trichlorobenzene, 1,2,4,5-tetrachlorobenzne and hexachlorobenzene) from aqueous samples. The quickMix-assisted msLLE-FEDHS approach achieved good absolute extraction recoveries (between 74.2% and 88.7%), low limits of detection (between 0.0006 and 0.0116 µg/L), good linearity (r2≥0.9920), good repeatability (between 1.9% and 8.4%, and good reproducibility (between 9.0% and 13.6%). It was found to be superior to the methods published by the United States Environmental Protection Agency. Five consecutive fully automated quickMix-assisted-msLLE-FEDHS-GC-MS runs spanned only ca. 4 hr.

Health Misinformation about Toxic-Site Harm: The Case for Independent-Party Testing to Confirm Safety.

Health misinformation can cause harm if regulators or private remediators falsely claim that a hazardous facility is safe. This misinformation especially threatens the health of children, minorities, and poor people, disproportionate numbers of whom live near toxic facilities. Yet, perhaps because of financial incentives, private remediators may use safety misinformation to justify reduced cleanup. Such incentives exist in nations like the United States, where most toxic-site testing/remediation is semi-privatized or voluntary, conducted by private parties, commercial redevelopers, who can increase profits by underestimating health harm, thus decreasing required testing/remediation. Our objective is to begin to determine whether or not interested parties misrepresent health harm (at hazardous facilities that they test/remediate/redevelop) when they use traditional and social media to claim that these sites are safe. Our hypothesis is that, contrary to the safety claims of the world’s largest commercial developer, Coldwell Banker Real Estate/Trammell Crow (CBRE/TCC), the authors’ screening assessment, especially its lab-certified, toxic-site, indoor-air tests, show violations of all three prominent government, cancer-safety benchmarks. If so, these facilities require additional testing/remediation, likely put site renters at risk, and may reveal problems with privatized hazardous cleanup. To our knowledge, we provide the first independent tests of privatized, toxic-site assessments before cancer reports occur. Our screening assessment of this hypothesis tests indoor air in rental units on a prominent former weapons-testing site (the US Naval Ordnance Testing Station, Pasadena, California (NOTSPA) that is subject to carcinogenic vapor intrusion by volatile organic compounds, VOCs), then compares test results to the redeveloper’s site-safety claims, made to government officials and citizens through traditional and social media. Although NOTSPA toxic soil-gas concentrations are up to nearly a million times above allowed levels, and indoor air was never tested until now, both the regulator and the remediator (CBRE/TCC) have repeatedly claimed on social media that “the site is safe at this time.” We used mainly Method TO-17 and two-week sampling with passive, sorbent tubes to assess indoor-air VOCs. Our results show that VOC levels at every location sampled—all in occupied site-rental units—violate all three government-mandated safety benchmarks: environmental screening levels (ESLs), No Significant Risk Levels (NSRLs), and inhalation risks based on the Inhalation Unit Risk (IUR); some violations are two orders of magnitude above multiple safety benchmarks. These results support our hypothesis and suggest a need for independent assessment of privatized cleanups and media-enhanced safety claims about them. If our results can be replicated at other sites, then preventing health misinformation and toxic-facility safety threats may require new strategies, one of which we outline.

Comparison of different models to calculate the viscosity of biogas and biomethane in order to accurately measure flow rates for conformity assessment

The study presents an optimised method to correct flow rates measured with a LFE flowmeter pre-set on methane while used for gas mixtures of unknown composition at the time of the measurement. The method requires the correction of the flow rate using a factor based on the viscosity of the gas mixtures once the composition is accurately known. The method has several different possible applications inclusive for the sampling of biogas and biomethane onto sorbent tubes for conformity assessment for the determination of siloxanes, terpenes and VOC in general. Five models for the calculation of the viscosity of the gas mixtures were compared and the models were used for ten binary mixtures and four multi-component mixtures. The results of the evaluation of the different models showed that the correction method using the viscosity of the mixtures calculated with the model of Reichenberg and Carr showed the smallest biases for binary mixtures. For multi-component mixtures, the best results were obtained when using the models of Lucas and Carr.

Real-time versus thermal desorption selected ion flow tube mass spectrometry for quantification of breath volatiles.

Selected ion flow tube mass spectrometry (SIFT-MS) is versatile, rapidly provides result output and determines a wide range of volatiles, making it suitable for biomedical applications. When direct sampling into the SIFT-MS instrument is impractical, combining thermal desorption (TD) and SIFT-MS might offer a solution as it allows sample storage on sorbent tubes for later analysis. This work compares off-line TD SIFT-MS and real-time SIFT-MS for the quantification of selected breath volatiles. Ten healthy non-smoking individuals provided 60 breath samples per method. For off-line analysis, breath was collected onto sorbent tubes via a breath sampler provided with filtered inspiratory air. After TD, samples were re-collected in Tedlar bags which were then connected to the SIFT-MS instrument. For real-time analysis, breath was sampled directly into the instrument. In both cases the analytical method included a total of 155 product ions, and 14 selected volatiles were quantified. The agreement between the methods was assessed using Pearson correlation coefficients and Bland-Altman plots. Overall, correlations between real-time and off-line analysis were moderate to very strong (r = 0.43-0.92) depending on the volatile of interest, except for 2,3-butanedione and styrene. The difference between real-time and off-line measured breath concentrations (average bias) ranged between -14.57 and 20.48 ppbv. For acetone and isoprene, it was 251.53 and 31.9 ppbv, respectively. Real-time SIFT-MS and off-line TD SIFT-MS for quantification of selected breath volatiles did not show optimal agreement. Analyzing a multitude of analytes in breath via direct exhalation into a SIFT-MS instrument for real-time analysis is challenging. On the other hand, off-line analysis using a breath collection device also has its issues such as possible sample losses due to selective absorption depending on the sorbent used or during desorption and transfer to the instrument. Despite these drawbacks, both methods were moderately well correlated.

Biomatrix of health risk assessment of benzene-exposed workers at Thai gasoline stations.

ObjectiveThis study assessed the health risk of benzene exposure among Thai gasoline station workers through biomarker detection and experience of adverse symptoms.MethodsTrans, trans‐muconic acid (tt‐MA) metabolites of benzene were analyzed from spot urine sampled among gasoline station workers after shift work using HPLC‐UV. Air benzene monitoring was done with an active sampler connected to a charcoal sorbent tube, and analyzed by GC‐FID. The health risk was calculated by using the biomatrix of the likelihood of benzene exposure and the severity of adverse symptoms.ResultsThe tt‐MA concentration, among 235 workers, ranged from less than 10–2159 µg/g Cr, which corresponded to the air benzene concentration range of <0.1 to 65.8 ppb. In total, 32.3% of workers had a higher than acceptable risk level and there was a significant association between gasoline station work zones and the likelihood of benzene exposure as well as the health risk of workers. The health risk levels estimated from the biomarker monitoring were consistent with the risk matrix of air benzene monitoring.ConclusionThis tt‐MA biomarker monitoring and biomatrix of health risk assessment is suggested as useful for health surveillance of gasoline station workers exposed to benzene.

A Low-Cost Open-Source Air Sampler for the Sorbent Tube Sampling for TD-GC/MS Analysis

In this study, we provide full descriptions of how to make a low-cost and completely open-source laboratory-made air sampler that will be used for sample adsorption for thermal desorption-gas chromatography mass spectrometry (TD-GC/MS) analysis. It is well known that harmful gases cause bad effects on human bodies, so it is necessary to identify the types and amounts of gases in industrial sites. One of the most commonly used methods for gas sampling is to utilize a sorbent tube using an air sampler. Commercially available air samplers are expensive, typically priced between $1,000 and $2,000, and their design often cannot be modified to fit the experiment. To address these shortcomings, we have developed a do-it-yourself (DIY) air sampler that is not only cheap enough, but also completely open-source. Furthermore, the performance of the fabricated air sampler was validated in conjunction with TD-GC/MS for the analysis of volatile compounds.

Custom pyrolyzer for the pyrolysis of chemical warfare agents

Thermal decomposition studies on a chemical warfare agent (CWA) simulant was performed using a custom built pyrolyzer. The goals of this study were to design, build and evaluate a simple pyrolyzer to meet the safety and security requirements necessary to obtain consistent CWA and CWA simulant pyrolysis data from multiple laboratories around the world. A custom made tubular flow reactor was built, the pyrolysis effluent was collected on solid sorbent tubes, and was analyzed by thermal desorption (TD) gas chromatography/mass spectrometry (GC/MS). Experiments were conducted with triethyl phosphate (TEP), a well-studied CWA simulant, to determine the activation energy (Ea) and rate constant (k) for the unimolecular decomposition of TEP under the designed experimental conditions and to validate pyrolyzer performance. Experiments with TEP were conducted at five different temperatures (375–440 °C) with samples collected at five flow rates. The activation energy for TEP decomposition was determined to be 32.0 ± 7.6 kcal/mol which is consistent with previous reported literature data.

Detection and quantification of exhaled volatile organic compounds in mechanically ventilated patients - comparison of two sampling methods.

Exhaled breath analysis is a promising new diagnostic tool, but currently no standardised method for sampling is available in mechanically ventilated patients. We compared two breath sampling methods, first using an artificial ventilator circuit, then in "real life" in mechanically ventilated patients on the intensive care unit. In the laboratory circuit, a 24-component synthetic-breath volatile organic compound (VOC) mixture was injected into the system as air was sampled: (A) through a port on the exhalation limb of the circuit and (B) through a closed endo-bronchial suction catheter. Sorbent tubes were used to collect samples for analysis by thermal desorption-gas chromatography-mass spectrometry. Realistic mechanical ventilation rates and breath pressure-volume loops were established and method detection limits (MDLs) were calculated for all VOCs. Higher yields of VOCs were retrieved using the closed suction catheter; however, for several VOCs MDLs were compromised due to the background signal associated with plastic and rubber components in the catheters. Different brands of suction catheter were compared. Exhaled VOC data from 40 patient samples collected at two sites were then used to calculate the proportion of data analysed above the MDL. The relative performance of the two methods differed depending on the VOC under study and both methods showed sensitivity towards different exhaled VOCs. Furthermore, method performance differed depending on recruitment site, as the centres were equipped with different brands of respiratory equipment, an important consideration for the design of multicentre studies investigating exhaled VOCs in mechanically ventilated patients.

Phase distribution and risk assessment of PAHs in ambient air of Hamadan, Iran

In the present study, both gaseous and particulate (PM with dae <2.5 µm) phases of polycyclic aromatic hydrocarbons (PAHs) were measured in the ambient air of Hamadan city, Iran. For this reason, two low-volume samplers equipped with glass fiber filters were used for sampling of particulate phase (N = 30) and XAD-2 sorbent tubes were applied for sampling gaseous phase of PAHs (N = 30). The sampling was conducted during warm and cold seasons in 2019. The average of cold/warm season ratios for Σ16PAH and PM concentrations were 1.14 and 0.62, respectively. Summed PAHs concentration were determined to be in the range 0.008–59.46 (mean: 11.61) ng/m3 and 0.05–40.83 (mean: 10.22) ng/m3 for the cold and warm seasons, respectively. A negative Pearson correlation coefficient was obtained for wind speed and relative humidity. The average Benzo (a) Pyrene equivalent carcinogenic (BaPeq) levels in the cold season were lower than the maximum permissible risk level of 1 ng/m3 for BaP. The BaP toxicity equivalency (ΣBaPTEQ) and BaP mutagenicity equivalency (ΣBaPMEQ) appeared to be significantly higher in the cold season (averaging 0.35 and 1.65 ng/m3, respectively) than those in warm season. Health risk assessment was performed for children and adults based on BaPeq, inhalation cancer risk. The diagnostic ratios of individual PAHs concentration showed that the significant sources of PAH emissions may be related to light duty vehicles (LDVs) in Hamadan. Although, some other sources such as pyrogenic source and petrol combustion were also suggested.

Breath Analysis: Comparison among Methodological Approaches for Breath Sampling.

Despite promising results obtained in the early diagnosis of several pathologies, breath analysis still remains an unused technique in clinical practice due to the lack of breath sampling standardized procedures able to guarantee a good repeatability and comparability of results. The most diffuse on an international scale breath sampling method uses polymeric bags, but, recently, devices named Mistral and ReCIVA, able to directly concentrate volatile organic compounds (VOCs) onto sorbent tubes, have been developed and launched on the market. In order to explore performances of these new automatic devices with respect to sampling in the polymeric bag and to study the differences in VOCs profile when whole or alveolar breath is collected and when pulmonary wash out with clean air is done, a tailored experimental design was developed. Three different breath sampling approaches were compared: (a) whole breath sampling by means of Tedlar bags, (b) the end-tidal breath collection using the Mistral sampler, and (c) the simultaneous collection of the whole and alveolar breath by using the ReCIVA. The obtained results showed that alveolar fraction of breath was relatively less affected by ambient air (AA) contaminants (p-values equal to 0.04 for Mistral and 0.002 for ReCIVA Low) with respect to whole breath (p-values equal to 0.97 for ReCIVA Whole). Compared to Tedlar bags, coherent results were obtained by using Mistral while lower VOCs levels were detected for samples (both breath and AA) collected by ReCIVA, likely due to uncorrected and fluctuating flow rates applied by this device. Finally, the analysis of all data also including data obtained by explorative analysis of the unique lung cancer (LC) breath sample showed that a clean air supply might determine a further confounding factor in breath analysis considering that lung wash-out is species-dependent.

Application of a new solid adsorbent tube for the determination of three kinds of epoxy eompounds in air

Objective: To develop a new solid sorbent tube for simultaneously capturing ethylene oxide (EO) , propylene oxide (PO) and epichlorohydrin (ECH) in air, and establish a complete set of method. Methods: In June 2018, EO, PO and ECH in air were captured by the new solid sorbent tube filled with carbon aerogel adsorbent, desorbed with solution of 5% (V/V) methanol-methylene chloride, separated through capillary chromatographic column, and then analyzed by gas chromatography-flame ionization detector. Results: The linear ranges of EO, PO and ECH were 0.24-960.00, 0.60-2384.00 and 0.12-472.40 mg/L respectively, and the related coefficients were between 0.99995-0.99997. The relative standard deviations (RSD) within the group were 1.66%-4.09%, 1.36%-4.43%, and 1.99%-5.65%, respectively, and the RSD between the group were 2.69%-4.95%, 2.77%-5.30%, and 3.27%-6.67%, respectively. The average desorption efficiencies were 88.25%-94.50%, 98.17%-98.60%, and 97.79%-101.04%, respectively. The samples could be stored at 4 ℃ refrigerator for at least 27 days. Conclusion: The newly developed solid sorbent tube filled with carbon aerogel adsorbent and its complete set of gas chromatography method could be used for sampling and quantitative detection of EO, PO and ECH in workplace air.