Comparison of HiSorb probes and sorbent tubes for the determination of VOCs emitted by two historical snuffboxes

Recovery and reactivity of polycyclic aromatic hydrocarbons collected on selected sorbent tubes and analyzed by thermal desorption-gas chromatography/mass spectrometry

Quantification of odorants from animal production facilities is difficult. The current technique is to collect airsamples in Tedlar bags and quantify odor using a trained olfactory panel. In this approach, relative differences betweensamples can be determined, but further quantification of odorants is limited. An alternative approach is to quantify odorantsin air emissions using sorbent tubes. A sorbent tube is a glass tube packed with a specific adsorbent material (Tenax TA,Carboxen 1000, Carbosieve SIII, etc.) and has been used to collect volatiles and quantify emissions from various industrialsources. Each adsorbent has a limited range of chemical selectivity. Limited applications of sorbent tubes with single or dualadsorbents have been used to measure odorant emissions from animal production facilities.<br><br>In this study, tripacked sorbent tubes and Tedlar bags were compared in characterizing 19 major odorants found inartificial swine odor. The sorbent tubes were packed with Tenax TA, Carboxen 1000, and Carbosieve SIII. The artificial swineodor was directly desorbed onto the tripacked sorbent tube. For comparison, a 10L Tedlar bag was filled with nitrogen gasand artificial swine odor. The Tedlar bag was then desorbed onto the tripacked sorbent tube. The sorbent tube was thenthermally desorbed into a gas chromatography (GC) system with a flame ionization detector (FID) for quantification. Thetripacked sorbent tube demonstrated recoveries greater than 74% and detection limits less than 0.4 ng for all 19 odorants.Thus, a tripacked sorbent tube may provide an analytical method to measure low concentrations of major odorants foundin air emissions from swine production facilities. Tedlar bags showed limited recoveries of some odorants, less than 12% forindole and skatole. In addition, Tedlar bags immediately sampled after three flushings with nitrogen emitted 3.50 ng L1 hr1of acetic acid (~35% above background levels) and 2.13 ng L1 hr1 phenol (~27% above background levels). These resultssuggest that air samples collected in Tedlar bags may bias olfactory analysis.

Introduction. Variable analytical control methodologies are applied in monitoring over contents of low molecular weight organic compounds in ambient air. Their unification is a vital and serious challenge requiring valid substantiation and selection of optimal air sampling techniques. Our research goal was to substantiate and select an air sampling technique for chemical analysis of furan and methylfuran. Materials and methods. Our research concentrated on developing and optimizing the process of air samples preparation for chemical analysis of furan and methylfuran; examining effectiveness of furan and methylfuran sorption-desorption using various sorbents. Standard furan and methylfuran samples (≥99.0% Sigma-Aldrich), heptane solvents, sorbent tubes with Tenax, Sylochrom C-120, and coal as sorbents were used in the research. All experimental studies were aimed at testing effective procedures for taking and preparing air samples for further furan and methylfuran analysis in them. They were performed on “Kristall-5000” gas chromatographer with mass-selective detection (MSD) and 25-meter long PoraPlotQ-capillary column. Results. We comparatively analyzed the results produced by taking air samples for further detection of furan and methylfuran in them using different techniques. They included low temperature concentration; sorption on filters made of quartz microfiber and a sorbent tube with Nenax TA; sorption on a tube with Tenax TA at t=20-25 °C. The analysis enabled us to reveal an effective procedure for taking ambient air samples for further detection of furan and methylfuran in them. This procedure was low temperature concentration of low molecular weight organic compounds on a sorbent tube with Tenax TA. Limitations. The accomplished study had no limitations. Conclusion. The accomplished study allows us to recommend taking air samples during 10 minutes with consumption being 0.1 l/min for further detection of furan and methylfuran in them using low temperature concentration on a sorbent tube with Tenax TA. The achieved effectiveness is 99.2% for furan and 100% for methylfuran.

Not all volatile organic compounds (VOCs) are suitable for sampling from air onto sorbent tubes (ST) with subsequent analysis by thermal desorption (TD) with gas chromatography (GC). Some compounds (such as C2 hydrocarbons) are too volatile for quantitative retention by sorbents at ambient temperature, while others are too reactive - either for storage stability on the tubes (post-sampling) or for thermal desorption/GC analysis. Volatile fatty acids (VFAs) are one of the compound groups that present a challenge to sorbent tube sampling. In this study, we evaluated sample losses on the inner wall surface of the sorbent tube sampler. The sorptive losses of five VFA (acetic, propionic, n-butyric, i-valeric, and n-valeric acid) were tested using two types of tubes (stainless steel and quartz), each packed with three sorbent beds arranged in order of sorbent strength from the sampling end of the tube (Tenax TA, Carbopack B, and Carbopack X). It showed significantly higher losses of VFAs in both liquid phase and vapor phase when using stainless steel tube samplers. These losses were also seen if vapor-phase fatty acids were passed through empty stainless steel tubing and increased dramatically with increasing molecular weight, e.g., losses of 33.6% (acetic acid) to 97.5% (n-valeric acid). Similar losses of VFAs were also observed from headspace sampling of cheese products. Considering that stainless steel sampling tubes are still used extensively by many researchers, their replacement with quartz tubes is recommended to reduce systematic biases in collecting VFA samples or in their calibration.

Odor samples collected in field research are complex mixtures of hundreds if not thousands of compounds. Research is needed to know how best to sample and analyze these compounds. The main objective of this research was to compare recoveries of a standard gas mixture of 11 odorous compounds from the Carboxen/PDMS 75 μm SPME fibers, PVF (Tedlar), FEP (Teflon), foil, and PET (Melinex) air sampling bags, sorbent Tenax TA tubes and standard 6 L Stabilizer™ sampling canisters after sample storage for 0.5, 24, and 120 (for sorbent tubes only) hrs at room temperature. The standard gas mixture consisted of 7 volatile fatty acids (VFAs) from acetic to hexanoic, and 4 semi‐VOCs including p‐cresol, indole, 4‐ethylphenol, and 2’‐aminoacetophenone with concentrations ranging from 5.1 ppb for indole to 1, 270 ppb for acetic acid. On average, SPME had the highest mean recovery for all 11 gases of 106.2%, and 98.3% for 0.5 and 24 hrs sample storage time, respectively. This was followed by the Tenax TA sorbent tubes (94.8% and 88.3%) for 24 and 120 hrs, respectively; PET bags (71.7% and 47.2%), FEP bags (75.4% and 39.4%), commercial Tedlar bags (67.6% and 22.7%), in‐house‐made Tedlar bags (47.3% and 37.4%), foil bags (16.4% and 4.3%), and canisters (4.2% and 0.5%), for 0.5 and 24 hrs, respectively. VFAs had higher recoveries than semi‐VOCs for all bags and canisters. New FEP bags and new foil bags had the lowest and the highest amounts of chemical impurities, respectively. New commercial Tedlar bags had measurable concentrations of N, N‐dimethyl acetamide and phenol. Foil bags had measurable concentrations of acetic, propionic, butyric, valeric and hexanoic acids.

Comparison of two common adsorption materials for thermal desorption gas chromatography – mass spectrometry of biogenic volatile organic compounds

Finding rugged and farm-proven sampling methods for odor measurement and mitigation of emissions continues to be a challenge. The objective was to develop a new method to quantify odorous volatile organic compounds (VOCs) in air. The main goal was to transform a fragile lab-based technology into a sampler that can be deployed for longer periods of time in remote locations. The developed method uses improved solid-phase microextraction (SPME) for combined on-site air sampling and sampling preparation. No power source is needed, and the technique is solvent-less. SPME fiber is exposed inside a protective glass liner. Thus, extraction of odorants is controlled by diffusion. Gas chromatography coupled with mass spectrometry is used for sample analysis in the laboratory. Acetic acid was chosen as a model compound to prove the concept. In the new method, extraction of acetic acid had a linear relationship with extraction time (R2<0.99). The Car/PDMS 85 à à µm fiber was shown to have better sensitivity for acetic acid. The effects of glass liner condition and diffusion path length on mass extraction were studied. The new method was evaluated under field conditions by comparing it to the standard method (sorbent tubes) in four different locations. This research shows that SPME fiber retracted inside a glass liner is a low-cost, simple, yet accurate sampling technique for quantification of odorous VOCs.

The superiority of thermal desorption-gas chromatography (TD-GC) applications is well known for the analysis of biogenic volatile organic compounds (BVOC). Despite the recognition of potential biases associated with sorptive loss reaction, the interaction of reactive BVOC with a sorbent tube (ST) sampler has not been sufficiently investigated. In this study, the extent of such a loss on a sampling device was studied against the sorbent holder materials by comparing stainless steel (SS; main target) and quartz (QZ; reference). To this end, three bed STs (Tenax TA, Carbopack B, and Carbopack X) were prepared using both holding materials (SS vs. QZ). The extent of BVOC loss was then tested for each material against two different phases (liquid and vapor) of ten monoterpenes. Accordingly, the soptive loss on the SS holder ranged from 10 % (vapor) to 20 % (liquid). If a vapor phase BVOC was forced to pass through an empty SS tube, the extent of their loss increased further in a range of 21.1 % (β-P) to 43.5 % (α-T). Likewise, similar loss rates (about 10 % reductions) were also observed when analyzing some environmental samples (pine needle) from the SS holder relative to QZ. Thus, a QZ tube is recommended over a SS tube to avoid sample loss in the collection of BVOC.

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 (&gt; 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 &lt; +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.

Finding farm-proven, robust sampling technologies for measurement of odorous volatile organic compounds (VOCs) and evaluating the mitigation of nuisance emissions continues to be a challenge. The objective of this research was to develop a new method for quantification of odorous VOCs in air using time-weighted average (TWA) sampling. The main goal was to transform a fragile lab-based technology (i.e., solid-phase microextraction, SPME) into a rugged sampler that can be deployed for longer periods in remote locations. The developed method addresses the need to improve conventional TWA SPME that suffers from the influence of the metallic SPME needle on the sampling process. We eliminated exposure to metallic parts and replaced them with a glass tube to facilitate diffusion from odorous air onto an exposed SPME fiber. A standard gas chromatography (GC) liner recommended for SPME injections was adopted for this purpose. Acetic acid, a common odorous VOC, was selected as a model compound to prove the concept. GC with mass spectrometry (GC–MS) was used for air analysis. An SPME fiber exposed inside a glass liner followed the Fick’s law of diffusion model. There was a linear relationship between extraction time and mass extracted up to 12 h (R2 > 0.99) and the inverse of retraction depth (1/Z) (R2 > 0.99). The amount of VOC adsorbed via the TWA SPME using a GC glass liner to protect the SPME was reproducible. The limit of detection (LOD, signal-to-noise ratio (S/N) = 3) and limit of quantification (LOQ, S/N = 5) were 10 and 18 µg·m−3 (4.3 and 7.2 ppbV), respectively. There was no apparent difference relative to glass liner conditioning, offering a practical simplification for use in the field. The new method related well to field conditions when comparing it to the conventional method based on sorbent tubes. This research shows that an SPME fiber exposed inside a glass liner can be a promising, practical, simple approach for field applications to quantify odorous VOCs.

The volatile organic compounds in seized cocaine hydrochloride were analyzed using Gas Chromatography Mass Spectrometry (GC/MS). Two different methods of sampling volatile compounds were investigated. In the first method, 20, 50, and 100 mg samples of seized cocaine hydrochloride were loaded into 2-inch glass tubes. The headspace of each tube was then purged with ultra high purity (UHP) helium and the gas exiting the tube was directed through a cryogenic loop filled with glass beads and maintained at liquid nitrogen temperature. The volatile organic compounds were collected onto the glass beads while the helium gas was vented. The organic compounds were subsequently thermally desorbed onto the column and analyzed by GC/MS. In the second method, 10 mg and 100 mg samples of seized cocaine hydrochloride were loaded into glass tubes fitted with glass frits at one end. UHP helium was purged through each sample and the purge gas containing organic compounds was collected onto a sorbent tube packed with Tenax TA. The concentrated organic compounds were then thermally desorbed onto a 4 m section of a split GC capillary column maintained at -70 degrees C with flow rates of 20-28 ml/min. Flow was returned to 2.8 ml/min during analysis. By sampling the seized samples of cocaine hydrochloride using a cryogenic loop, methanol, methyl ethyl ketone, acetic acid, 2,2,4-trimethyl pentane, 2-methyl pentane, dichloromethane, 2-propanol, and 2-propanol, and 2-propane (acetone) were found in three different seized cocaine hydrochloride samples. The observed quantities of these volatile organic compounds were different for each of the three seized cocaine hydrochloride samples. THe observed quantities of these volatile organic compounds were different for each of the three seized samples labeled A, B, and C. By sampling the seized samples of cocaine hydrochloride using sorbent tubes, cocaine was consistently observed. Although volatile components other than cocaine were observed, the number and amount of volatile components were not consistent with the cryogenic loop results.

This dataset contains raw area counts and percent recoveries of polycyclic aromatic hydrocarbon (PAH) standards desorbed from selected sorbent tubes and analyzed using thermal desorption-gas chromatography/mass spectrometry (TD-GC/MS). The results of this study were published in the article “Recovery and reactivity of polycyclic aromatic hydrocarbons collected on selected sorbent tubes and analyzed by thermal desorption-gas chromatography/mass spectrometry” in Journal of Chromatography A [1]. The sorbent tubes studied include stainless steel Carbograph 2TD/1TD, glass quartz wool-Carbograph 2TD, inert-coated stainless steel Carbograph 2TD, glass and stainless steel Tenax TA, PAH (chemical weapons), and glass and stainless steel XRO-440 sorbent tubes. Tables listing the experimental conditions, TD methods, and types of sorbent tubes are included in the manuscript. Data for experiments, including the investigation of incomplete desorption of PAHs from Carbograph 2TD/1TD and XRO-440 sorbent tubes, the comparison of PAH recoveries from three different TD methods, the analysis of PAH breakthrough from sorbent tubes, the investigation of the effect of heat on PAH percent recovery from sorbent tubes, and the formation of reaction products during PAH loading and desorption are included in Appendix A. These data can be used to guide sorbent tube selection for PAH analyses in future studies.

Evaluation of potential sample contamination from a self-designed automatic device for volatile organic compounds (VOCs) active air sampling.

Quantification of cancer biomarkers in urine using volatilomic approach

Odorous gases associated with livestock operations are complex mixtures of hundreds if not thousands of compounds. Research is needed to know how best to sample and analyze these compounds. The main objective of this research was to compare recoveries of a standard gas mixture of 11 odorous compounds from the Carboxen/PDMS 75–μm solid–phase microextraction fibers, polyvinyl fluo–ride (PVF; Tedlar), fluorinated ethylene propylene copolymer (FEP; Teflon), foil, and polyethylene terephthalate (PET; Melinex) air sampling bags, sorbent 2,b–diphenylene–oxide polymer resin (Tenax TA) tubes, and standard 6–L Stabilizer sampling canisters after sample storage for 0.5, 24, and 120 (for sorbent tubes only) hrs at room temperature. The standard gas mixture consisted of 7 volatile fatty acids (VFAs) from acetic to hexanoic, and 4 semivolatile organic compounds including p–cresol, indole, 4–ethylphenol, and 2'–aminoacetophenone with concentrations ranging from 5.1 ppb for indole to 1270 ppb for acetic acid. On average, SPME had the highest mean recovery for all 11 gases of 106.2%, and 98.3% for 0.5– and 24–hr sample storage time, respectively. This was followed by the Tenax TA sorbent tubes (94.8% and 88.3%) for 24 and 120 hr, respectively; PET bags (71.7% and 47.2%), FEP bags (75.4% and 39.4%), commercial Tedlar bags (67.6% and 22.7%), in–house–made Tedlar bags (47.3% and 37.4%), foil bags (16.4% and 4.3%), and canisters (4.2% and 0.5%), for 0.5 and 24 hr, respectively. VFAs had higher recoveries than semivolatile organic compounds for all of the bags and canisters. New FEP bags and new foil bags had the lowest and the highest amounts of chemical impurities, respectively. New commercial Tedlar bags had measurable concentrations of N,N–dimethyl acetamide and phenol. Foil bags had measurable concentrations of acetic, propionic, butyric, valeric, and hexanoic acids.