Sampling and Determination of Formaldehyde Using Solid-Phase Microextraction with On-Fiber Derivatization

What are the DNA lesions underlying formaldehyde toxicity?

Formaldehyde is a highly reactive organic compound. Humans can be exposed to exogenous sources of formaldehyde, but formaldehyde is also produced endogenously as a byproduct of cellular metabolism. Because formaldehyde can react with DNA, it is considered a major endogenous source of DNA damage. However, the nature of the lesions underlying formaldehyde toxicity in cells remains vastly unknown. Here, we review the current knowledge of the different types of nucleic acid lesions that are induced by formaldehyde and describe the repair pathways known to counteract formaldehyde toxicity. Taking this knowledge together, we discuss and speculate on the predominant lesions generated by formaldehyde, which underly its natural toxicity.

Development of a Fully Automated Method HS-SPME-GC-MS/MS for the Determination of Odor-Active Carbonyls in Wines: a "Green" Approach to Improve Robustness and Productivity in the Oenological Analytical Chemistry

The aim of this study was the optimization and validation of a green, robust, and comprehensive method for the determination of volatile carbonyl compounds (VCCs) in wines that could be added as a new quality control tool for the evaluation of a complete fermentation, correct winemaking style, and proper bottling and storage. A HS-SPME-GC-MS/MS method was optimized and automated using the autosampler to improve overall performance. A solvent-less technique and a strong minimization of all volumes were implemented to comply with the green analytical chemistry principles. There were as many as 44 VCC (mainly linear aldehydes, Strecker aldehydes, unsaturated aldehydes, ketones, and many other) analytes under investigation. All compounds showed a good linearity, and the LOQs were abundantly under the relevant perception thresholds. Intraday, 5-day interday repeatability, and recovery performances in a spiked real sample were evaluated showing satisfactory results. The method was applied to determine the evolution of VCCs in white and red wines after accelerated aging for 5 weeks at 50 °C. Furans and linear and Strecker aldehydes were the compounds that showed the most important variation; many VCCs increased in both classes of samples, whereas some showed different behaviors between white and red cultivars. The obtained results are in strong accordance with the latest models on carbonyl evolution related to wine aging.

K6-linked ubiquitylation marks formaldehyde-induced RNA-protein crosslinks for resolution

Reactive aldehydes are produced by normal cellular metabolism or after alcohol consumption, and they accumulate in human tissues if aldehyde clearance mechanisms are impaired. Their toxicity has been attributed to the damage they cause to genomic DNA and the subsequent inhibition of transcription and replication. However, whether interference with other cellular processes contributes to aldehyde toxicity has not been investigated. We demonstrate that formaldehyde induces RNA-protein crosslinks (RPCs) that stall the ribosome and inhibit translation in human cells. RPCs in the messenger RNA (mRNA) are recognized by the translating ribosomes, marked by atypical K6-linked ubiquitylation catalyzed by the RING-in-between-RING (RBR) E3 ligase RNF14, and subsequently resolved by the ubiquitin- and ATP-dependent unfoldase VCP. Our findings uncover an evolutionary conserved formaldehyde-induced stress response pathway that protects cells against RPC accumulation in the cytoplasm, and they suggest that RPCs contribute to the cellular and tissue toxicity of reactive aldehydes.

A New Perspective on SPME and SPME Arrow: Formaldehyde Determination by On-Sample Derivatization Coupled with Multiple and Cooling-Assisted Extractions

Formaldehyde (FA) is a toxic compound and a human carcinogen. Regulating FA-releasing substances in commercial goods is a growing and interesting topic: worldwide production sectors, like food industries, textiles, wood manufacture, and cosmetics, are involved. Thus, there is a need for sensitive, economical, and specific FA monitoring tools. Solid-phase microextraction (SPME), with O-(2,3,4,5,6-pentafluorobenzyl)-hydroxylamine (PFBHA) on-sample derivatization and gas chromatography, is proposed for FA monitoring of real-life samples. This study reports the use of polydimethylsiloxane (PDMS) as a sorbent phase combined with innovative commercial methods, such as multiple SPME (MSPME) and cooling-assisted SPME, for FA determination. Critical steps, such as extraction and sampling, were evaluated in method development. The derivatization was performed at 60 °C for 30 min, followed by 15 min sampling at 10 °C, in three cycles (SPME Arrow) or six cycles (SPME). The sensitivity was satisfactory for the method's purposes (LOD-LOQ at 11-36 ng L^-1, and 8-26 ng L^-1, for SPME and SPME Arrow, respectively). The method's linearity ranges from the lower LOQ at trace level (ng L^-1) to the upper LOQ at 40 mg L^-1. The precision range was 5.7-10.2% and 4.8-9.6% and the accuracy was 97.4% and 96.3% for SPME and SPME Arrow, respectively. The cooling MSPME set-up applied to real commercial goods provided results of quality comparable to previously published data.

A CRISPR-Cas9 screen identifies EXO1 as a formaldehyde resistance gene

Fanconi Anemia (FA) is a rare, genome instability-associated disease characterized by a deficiency in repairing DNA crosslinks, which are known to perturb several cellular processes, including DNA transcription, replication, and repair. Formaldehyde, a by-product of metabolism, is thought to drive FA by generating DNA interstrand crosslinks (ICLs) and DNA-protein crosslinks (DPCs). However, the impact of formaldehyde on global cellular pathways has not been investigated thoroughly. Herein, using a pangenomic CRISPR-Cas9 screen, we identify EXO1 as a critical regulator of formaldehyde-induced DNA lesions. We show that EXO1 knockout cell lines exhibit formaldehyde sensitivity leading to the accumulation of replicative stress, DNA double-strand breaks, and quadriradial chromosomes, a typical feature of FA. After formaldehyde exposure, EXO1 is recruited to chromatin, protects DNA replication forks from degradation, and functions in parallel with the FA pathway to promote cell survival. In vitro, EXO1-mediated exonuclease activity is proficient in removing DPCs. Collectively, we show that EXO1 limits replication stress and DNA damage to counteract formaldehyde-induced genome instability.

Approaches to Formaldehyde Measurement: From Liquid Biological Samples to Cells and Organisms

Formaldehyde (FA) is the simplest aldehyde present both in the environment and in living organisms. FA is an extremely reactive compound capable of protein crosslinking and DNA damage. For a long time, FA was considered a “biochemical waste” and a by-product of normal cellular metabolism, but in recent decades the picture has changed. As a result, the need arose for novel instruments and approaches to monitor and measure not only environmental FA in water, cosmetics, and household products, but also in food, beverages and biological samples including cells and even organisms. Despite numerous protocols being developed for in vitro and in cellulo FA assessment, many of them have remained at the “proof-of-concept” stage. We analyze the suitability of different methods developed for non-biological objects, and present an overview of the recently developed approaches, including chemically-synthesized probes and genetically encoded FA-sensors for in cellulo and in vivo FA monitoring. We also discuss the prospects of classical methods such as chromatography and spectrophotometry, and how they have been adapted in response to the demand for precise, selective and highly sensitive evaluation of FA concentration fluctuations in biological samples. The main objectives of this review is to summarize data on the main approaches for FA content measurement in liquid biological samples, pointing out the advantages and disadvantages of each method; to report the progress in development of novel molecules suitable for application in living systems; and, finally, to discuss genetically encoded FA-sensors based on existing natural biological FA-responsive elements.

Screening check test to confirm the relative reactivity and applicability of 2,4‐dinitrophenylhydrazine impregnated‐filters for formaldehyde on other compounds

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Deep Eutectic Solvent-Based Coating Sorbent for Preconcentration of Formaldehyde by Thin-Film Solid-Phase Microextraction Technique

A thin-film solid-phase microextraction method with a sorbent composed of a deep eutectic solvent was developed for the preconcentration of formaldehyde from river and lake water samples. Four new deep eutectic solvents (DESs) were synthesized, each in molar ratios 1:1, 1:2, and 1:3. Among prepared compounds, the greatest efficiency in the proposed method of preconcentration of formaldehyde derivatized with Nash reagent was demonstrated by DES-3 consisting of benzyldimethylhexadecylammonium chloride and lauric acid, in a molar ratio of 1:3. For the proposed method, the parameters affecting the extraction efficiency of formaldehyde were optimized (including the choice of DES-based sorbent and desorption solvent as well as the sample volume and pH, the salting-out effect, the extraction time, and the desorption time). Under optimal conditions, the proposed method achieved good precision between 3.3% (for single sorbent) and 4.8% (for sorbent-to-sorbent) as well as good recovery ranging from 78.0 to 99.1%. The limits of detection and quantitation were 0.15 ng mL−1 and 0.50 ng mL−1, respectively. The enrichment factor was equal to 178. The developed method was successfully applied to determine formaldehyde in environmental water samples.

In Vivo Solid-Phase Microextraction and Applications in Environmental Sciences

Solid-phase microextraction (SPME) is a well-established sample-preparation technique for environmental studies. The application of SPME has extended from the headspace extraction of volatile compounds to the capture of active components in living organisms via the direct immersion of SPME probes into the tissue (in vivo SPME). The development of biocompatible coatings and the availability of different calibration approaches enable the in vivo sampling of exogenous and endogenous compounds from the living plants and animals without the need for tissue collection. In addition, new geometries such as thin-film coatings, needle-trap devices, recession needles, coated tips, and blades have increased the sensitivity and robustness of in vivo sampling. In this paper, we detail the fundamentals of in vivo SPME, including the various extraction modes, coating geometries, calibration methods, and data analysis methods that are commonly employed. We also discuss recent applications of in vivo SPME in environmental studies and in the analysis of pollutants in plant and animal tissues, as well as in human saliva, breath, and skin analysis. As we show, in vivo SPME has tremendous potential for the targeted and untargeted screening of small molecules in living organisms for environmental monitoring applications.

Using experimental and computational approaches to probe an unusual carbon-carbon bond cleavage observed in the synthesis of benzimidazole N-oxides

Experimental and computational studies have been performed in order to investigate an unusual carbon-carbon bond cleavage that occurs in the preparation of certain benzimidazole N-oxides from anilines. The key factor determining the outcome of the reaction was found to be the substituents on the amine functionality of the aniline.

Two Aldehyde Clearance Systems Are Essential to Prevent Lethal Formaldehyde Accumulation in Mice and Humans

Reactive aldehydes arise as by-products of metabolism and are normally cleared by multiple families of enzymes. We find that mice lacking two aldehyde detoxifying enzymes, mitochondrial ALDH2 and cytoplasmic ADH5, have greatly shortened lifespans and develop leukemia. Hematopoiesis is disrupted profoundly, with a reduction of hematopoietic stem cells and common lymphoid progenitors causing a severely depleted acquired immune system. We show that formaldehyde is a common substrate of ALDH2 and ADH5 and establish methods to quantify elevated blood formaldehyde and formaldehyde-DNA adducts in tissues. Bone-marrow-derived progenitors actively engage DNA repair but also imprint a formaldehyde-driven mutation signature similar to aging-associated human cancer mutation signatures. Furthermore, we identify analogous genetic defects in children causing a previously uncharacterized inherited bone marrow failure and pre-leukemic syndrome. Endogenous formaldehyde clearance alone is therefore critical for hematopoiesis and in limiting mutagenesis in somatic tissues.

How improvements in monitoring and safety practices lowered airborne formaldehyde concentrations at an Italian university hospital: a summary of 20 years of experience

The last two decades have been crucial for the assessment of airborne formaldehyde (FA) exposure in healthcare environments due to changes in limits and reference values, definition of carcinogenicity, and new monitoring methods. The aim of this study was to analyse twenty years (1999–2019) of experience in automatic, continuous airborne FA monitoring in the Pathology Laboratory and operating rooms at the Careggi University Hospital, Florence, Italy. These 20 years saw gradual improvements in FA monitoring of exposed employees considered at maximum risk, including improvements in analytical methods of detection and sampling strategies, which came with changes in procedures and workflow operations. In 2019, after the adoption of safe practices, including a closed-circuit system using pre-loaded containers and a vacuum sealing, 94 % of the total measurements (FA concentrations) were lower than 16 μg/m³, and only 6 % ranged from 21 to 75 μg/m³. In the studied work units, the ratio between area and personal readings ranged from 0.9 to 1.0, both for long and short-term sampling. Personal sampling was simplified with a new workstation, which integrated different monitoring systems into an innovative ergonomic armchair equipped with personal sampling devices. Area monitoring was also improved with a real-time, continuous photoacoustic instrument. Over these 20 years, FA exposure significantly dropped, which coincided with optimised histology workflow and implementation of safety practices. For high-throughput screening and cost savings we propose an innovative ergonomic armchair station which allows remote continuous monitoring.

Solid phase microextraction techniques used for gas chromatography: a review

In the last decade, the development and adoption of greener and sustainable microextraction techniques have been proved to be an effective alternative to classical sample preparation procedures. In this review, 10 commercially available solid-phase microextraction systems are presented, with special attention to the appraisal of their analytical, bioanalytical, and environmental engineering. This review provides an overview of the challenges and achievements in the application of fully automated miniaturized sample preparation methods in analytical laboratories. Both theoretical and practical aspects of these environment-friendly preparation approaches are discussed. The application of chemometrics in method development is also discussed. We are convinced that green analytical chemistry will be really useful in the years ahead. The application of cheap, fast, automated, “clever”, and environmentally safe procedures to environmental, clinical, and food analysis will improve significantly the quality of the analytical data.

Pentagram-Shaped Ag@Pt Core-Shell Nanostructures as High-Performance Catalysts for Formaldehyde Detection

High-performance HCHO sensors are of great importance in various application fields such as indoor air quality assessments. Herein, bimetallic Ag-Pt nanoparticles are synthesized as high-performance catalysts for ZnO-based gas sensors. Spherical aberration (Cs)-corrected transmission electron microscopy images with atomic resolution clearly indicate that the prepared nanoparticles exhibit a novel Ag@Pt core-shell nanostructure with a pentagram shape. For high-performance HCHO sensor construction, integrated micro-electrodes are first fabricated with the microelectromechanical system (MEMS) technology. Then, the hydrothermal route is used to self-assemble well-aligned ZnO nanowire arrays onto the sensing microregion. After that, the pentagram-shaped Ag@Pt nanoparticles are loaded onto the surface of ZnO nanowires with the inkjet printing technique to form MEMS sensors with Ag@Pt@ZnO as the sensing material. The thoroughly sensing experiments indicate that the Ag@Pt nanoparticles exhibit satisfied catalytic activation to HCHO molecules. The experimental observed detection limit of our sensor to HCHO reaches the parts per billion level. To elucidate the HCHO-sensing mechanism, the online mass spectrum (online MS) is utilized to analyze the components of exhaust gas stream of HCHO flowing through the Ag@Pt@ZnO material. The online MS indicates that with the Ag@Pt catalyst, HCHO molecules are partially oxidized to HCOOH molecules at low temperatures and are completely oxidized to CO₂ molecules at high temperatures.

Determination of optimal sample preparation for aldehyde extraction from pale malts and their quantification via headspace solid-phase microextraction followed by gas chromatography and mass spectrometry

Aldehydes originating from malt play an important role in beer flavour deterioration. In order to better understand the influence of malting process on beer staling, it is necessary to acquire a reliable analytical methodology for determination of beer staling aldehydes in malt. Therefore, the aim of this study was to evaluate extraction parameters, which allow quantification of beer staling aldehydes present in pale malts. The method was validated with respect to linearity (R > 0.9988), limit of detection (0.28 - 0.99 μg/L), limit of quantification (0.92 - 3.31 μg/L), accuracy (± 5%), repeatability (1.3 - 5.3%) and intermediate precision (>20%). The following parameters of sample preparation were evaluated: sample amount, extraction time and temperature, ultrasonication time and oxygen level. Consequently, the best extraction conditions were successfully applied on pale malts. After extraction, the samples were analysed by headspace solid-phase microextraction (HS-SPME) with on fibre carbonyl derivatisation followed by gas chromatography and mass spectrometry (GC-MS). In addition, the salting-out effect during HS-SPME was studied. The method application allowed to identify significant differences (p ≤ 0.05) in the levels of aldehydes among various industrial scale, pale malts. The optimised method could give the information on the aldehyde content introduced into the brewing process and its potential contribution to the overall beer quality.

Oxidative stress in microbes after exposure to iron nanoparticles: analysis of aldehydes as oxidative damage products of lipids and proteins

Due to their enhanced reactivity, metal and metal-oxide nanoscale zero-valent iron (nZVI) nanomaterials have been introduced into remediation practice. To ensure that environmental applications of nanomaterials are safe, their possible toxic effects should be described. However, there is still a lack of suitable toxicity tests that address the specific mode of action of nanoparticles, especially for nZVI. This contribution presents a novel approach for monitoring one of the most discussed adverse effects of nanoparticles, i.e., oxidative stress (OS). We optimized and developed an assay based on headspace-SPME-GC-MS analysis that enables the direct determination of volatile oxidative damage products (aldehydes) of lipids and proteins in microbial cultures after exposure to commercial types of nZVI. The method employs PDMS/DVB SPME fibers and pentafluorobenzyl derivatization, and the protocol was successfully tested using representatives of bacteria, fungi, and algae. Six aldehydes, namely, formaldehyde, acrolein, methional, benzaldehyde, glyoxal, and methylglyoxal, were detected in the cultures, and all of them exhibited dose-dependent sigmoidal responses. The presence of methional, which was detected in all cultures except those including an algal strain, documents that nZVI also caused oxidative damage to proteins in addition to lipids. The most sensitive toward nZVI exposure in terms of aldehyde production was the yeast strain Saccharomyces cerevisiae, which had an EC₅₀ value of 0.08 g/L nZVI. To the best of our knowledge, this paper is the first to document the production of aldehydes resulting from lipids and proteins as a result of OS in microorganisms from different kingdoms after exposure to iron nanoparticles.

Toward ultrasensitive and fast colorimetric detection of indoor formaldehyde across the visible region using cetyltrimethylammonium chloride-capped bone-shaped gold nanorods as “chromophores”

A colorimetric method for detecting formaldehyde was developed by coupling bone-shaped gold nanorods (AuNRs) with silver mirror reaction, which enables low detection limit, wide linear range and high visual resolution.

Forced into aging: Analytical prediction of the flavor-stability of lager beer. A review

Despite years of research, sensory deterioration during beer aging remains a challenge to brewing chemists. Therefore, sensorial and analytical tools to investigate aging flavors are required. This review aims to summarize the available analytical methods and to highlight the problems associated with addressing the flavor-stability of beer. Carbonyls are the major contributors to the aroma of aged pale lager beer, which is especially susceptible to deterioration. They are formed via known pathways during storage, but, as recent research indicates, are mainly released from the bound-state during aging. However, most published studies are based on model systems, and thus the formation and breakdown parameters of these adducts are poorly understood. This concept has not been previously considered in previous forced-aging analysis. Only weak parallels can be drawn between forced and natural aging. This is likely due to the different activation energies of the chemical processes responsible for aging, but may also be due to heat-promoted release of bound aldehydes. Thus, precursors and their binding parameters must be investigated to make appropriate technological adjustments to forced-aging experiments. In combination with sophisticated data analysis, the investigation of volatile indicators and non-volatile precursors can lead to more reliable predictions of flavor stability.

Mechanistic insight into oxidizedN,N-dimethylacetamide as a source of formaldehyde related derivatives

Ahemiaminalderivative identified during preparation of the penultimate of ceftolozane1, mandated a thorough investigation of the source of the impurity.

Analysis of biogenic carbonyl compounds in rainwater by stir bar sorptive extraction technique with chemical derivatization and gas chromatography-mass spectrometry

Stir bar sorptive extraction is a powerful technique for the extraction and analysis of organic compounds in aqueous matrices. Carbonyl compounds are ubiquitous components in rainwater, however, it is a major challenge to accurately identify and sensitively quantify carbonyls from rainwater due to the complex matrix. A stir bar sorptive extraction technique was developed to efficiently extract carbonyls from aqueous samples following chemical derivatization by O‐(2,3,4,5,6‐pentafluorobenzyl) hydroxylamine hydrochloride. Several commercial stir bars in two sizes were used to simultaneously measure 29 carbonyls in aqueous samples with detection by gas chromatography with mass spectrometry. A 100 mL aqueous sample was extracted by stir bars and the analytes on stir bars were desorbed into a 2 mL solvent solution in an ultrasonic bath. The preconcentration Coefficient for different carbonyls varied between 30 and 45 times. The limits of detection of stir bar sorptive extraction with gas chromatography mass spectrometry for carbonyls (10–30 ng/L) were improved by ten times compared with other methods such as gas chromatography with electron capture detection and stir bar sorptive extraction with high‐performance liquid chromatography and mass spectrometry. The technique was used to determine carbonyls in rainwater samples collected in York, UK, and 20 carbonyl species were quantified including glyoxal, methylglyoxal, isobutenal, 2‐hydroxy ethanal.

A coupled sensor-spectrophotometric device for continuous measurement of formaldehyde in indoor environments

Despite long-standing awareness of adverse health effects associated with chronic human exposure to formaldehyde, this hazardous air pollutant remains a challenge to measure in indoor environments. Traditional analytical techniques evaluate formaldehyde concentrations over several hours to several days in a single location in a residence, making it difficult to characterize daily temporal and spatial variation in human exposure to formaldehyde. There is a need for portable, easy-to-use devices that are specific and sensitive to gas-phase formaldehyde over short sampling periods so that dynamic processes governing formaldehyde fate, transport, and potential remediation in indoor environments may be studied more effectively. A recently developed device couples a chemical sensor element with spectrophotometric analysis for detection and quantification of part per billion (ppbv) gas-phase formaldehyde concentrations. This study established the ability of the coupled sensor-spectrophotometric device (CSSD) to report formaldehyde concentrations accurately and continuously on a 30-min sampling cycle at low ppbv concentrations previously untested for this device in a laboratory setting. Determination of the method detection limit (MDL), based on 40 samples each at test concentrations of 5 and 10 ppbv, was found to be 1.9 and 2.0 ppbv, respectively. Performance of the CSSD was compared with the dinitrophenylhydrazine (DNPH) derivatization method for formaldehyde concentrations ranging from 5-50 ppbv, and a linear relationship with a coefficient of determination of 0.983 was found between these two analytical techniques. The CSSD was also used to monitor indoor formaldehyde concentrations in two manufactured homes. During this time, formaldehyde concentrations varied from below detection limit to 65 ppbv and were above the US National Institute for Occupational Safety and Health (NIOSH) recommended exposure limit (REL) of 16 ppbv, which is also the exposure limit value now adopted by the US Federal Emergency Management Agency (FEMA) to procure manufactured housing, 80% and 100% of the time, respectively.

Microfluidic lab-on-a-chip derivatization for gaseous carbonyl analysis

We present a microfluidic lab-on-a-chip derivatization technique for the analysis of gaseous carbonyl compounds using O-(2,3,4,5,6-pentafluorobenzyl) hydroxylamine (PFBHA) as the derivatizing reagent. The novel microfluidic lab-on-a-chip derivatization technique has been developed to measure nmol per mole (ppbv) mixing ratios of gaseous carbonyl compounds, which are of particular importance to atmospheric chemistry. The technique utilised a planar glass microreactor comprising three inlets and one outlet, gas and fluid splitting and combining channels, mixing junctions, and a 2.0m long, 620μm internal diameter reaction microchannel. The microreactor integrated three functions, providing: (1) a gas and liquid mixer and reactor, (2) reagent heating, and (3) sample pre-concentration. The concentration of derivatization solution, the volumetric flow rates of the incoming gas sample and PFBHA solution, and the temperature of the microreactor were optimised to achieve a near real-time measurement. The enhanced phase contact area-to-volume ratio and the high heat transfer rate in the microreactor resulted in a fast and high efficiency derivatization reaction, generating an effluent stream which was ready for direct introduction to GC-MS. Good linearity was observed for eight carbonyl compounds over the measurement ranges of 1-500ppbv when they were derivatized under optimal reaction conditions. The method detection limits (MDLs) were below 0.10nmolmol(-1) for most carbonyls in this study, which is below or close to their typical concentrations in clean ambient air. The performance of the technique was assessed by applying the methodology to the quantification of glyoxal (GLY) and methylglyoxal (MGLY) formed during isoprene photo-oxidation in an outdoor photoreactor chamber (EUPHORE). Good agreements between GLY and MGLY measurements were obtained comparing this new technique with Fourier Transform InfraRed (FTIR), which provides support for the potential effectiveness of the microfluidic technique for gaseous measurements.

On the origin of free and bound staling aldehydes in beer

The chemistry of beer flavor instability remains shrouded in mystery, despite decades of extensive research. It is, however, certain that aldehydes play a crucial role because their concentration increase coincides with the appearance and intensity of "aged flavors". Several pathways give rise to a variety of key flavor-active aldehydes during beer production, but it remains unclear as to what extent they develop after bottling. There are indications that aldehydes, formed during beer production, are bound to other compounds, obscuring them from instrumental and sensory detection. Because freshly bottled beer is not in chemical equilibrium, these bound aldehydes might be released over time, causing stale flavor. This review discusses beer aging and the role of aldehydes, focusing on both sensory and chemical aspects. Several aldehyde formation pathways are taken into account, as well as aldehyde binding in and release from imine and bisulfite adducts.

Volatile organics off-gassed among tobacco-exposed clothing fabrics

This work evaluates the characteristics of short-term release of volatile and semi-volatile organic chemicals from clothing fabrics that are exposed to environmental tobacco smoke (ETS). Various fabrics were concurrently exposed to ETS in a controlled facility, and the chemicals off-gassed were sampled using solid phase micro-extraction coupled with GC/MS analysis. Toluene-reference concentration (TRC) was calculated for nine selected chemicals and compared. The number of chemicals identified from ETS-exposed fabrics ranged from 13 (polyester and acetate) to 32 (linen). All fabrics off-gassed formaldehyde, tetradecanoic acid and n-hexadecanoic acid, while seven out of eight fabrics emitted furfural, benzonitrile, naphthalene and decanal. Natural fibers of plant origin (cotton and linen) off-gassed higher concentrations (TRC>100 μg/l) of chemicals that have low molecular weight (~100 or less) than did natural fibers of animal origin (wool and silk) and synthetic fibers. Conversely, wool and silk off-gassed more chemicals that are of high molecular weight (>200), such as TDA (TRC>100 μg/l) and n-HDA (TRC>500 μg/l), than did other fabrics. Fabric structure (for a particular material) significantly affects chemical off-gassing. Cotton typically used for polo shirt (knitted) off-gassed significantly (p<0.05) higher TRC for chemicals with molecular weight of ~100 (such as furfural) than did other cottons of woven style. The dyeing of fabric (white vs. black) had a limited effect on emission, while increasing contact time with ETS increased the intensity of chemical emissions. The mean TRC for cotton exposed for 12 min was nearly doubled than those exposed for 8min, but no difference existed for polyester.

Application of factorial designs to study factors involved in the determination of aldehydes present in beer by on-fiber derivatization in combination with gas chromatography and mass spectrometry

With the aim of studying the factors involved in on-fiber derivatization of Strecker aldehydes, furfural, and (E)-2-nonenal with O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine in beer, factorial designs were applied. The effect of the temperature, time, and NaCl addition on the analytes' derivatization/extraction efficiency was studied through a factorial 2(3) randomized-block design; all of the factors and their interactions were significant at the 95% confidence level for most of the analytes. The effect of temperature and its interactions separated the analytes in two groups. However, a single sampling condition was selected that optimized response for most aldehydes. The resulting method, combining on-fiber derivatization with gas chromatography-mass spectrometry, was validated. Limits of detections were between 0.015 and 1.60 μg/L, and relative standard deviations were between 1.1 and 12.2%. The efficacy of the internal standardization method was confirmed by recovery percentage (73-117%). The method was applied to the determination of aldehydes in fresh beer and after storage at 28 °C.

Locating industrial VOC sources with aircraft observations

Observation and characterization of environmental pollution, focussing on Volatile Organic Compounds (VOCs), in a high-risk industrial area, are particularly important in order to provide indications on a safe level of exposure, indicate eventual priorities and advise on policy interventions. The aim of this study is to use the Solid Phase Micro Extraction (SPME) method to measure VOCs, directly coupled with atmospheric measurements taken on a small aircraft environmental platform, to evaluate and locate the presence of VOC emission sources in the Marghera industrial area. Lab analysis of collected SPME fibres and subsequent analysis of mass spectrum and chromatograms in Scan Mode allowed the detection of a wide range of VOCs. The combination of this information during the monitoring campaign allowed a model (Gaussian Plume) to be implemented that estimates the localization of emission sources on the ground.