Headspace Air Research Articles

A Container Closure Integrity Test Method for Vials Stored at Cryogenic Conditions Using Headspace Oxygen Analysis.

An increasing number of pharmaceutical products require deep cold storage at cryogenic conditions, approximately -150°C to -190°C, to maintain stability and/or activity. Previous work has revealed that, at these extreme conditions, a typical pharmaceutical package configuration (vial, stopper, crimp cap) may lose container closure integrity (CCI) due to both the glass transition temperature (-55°C to -70°C) of the rubber stopper used to seal the vial and the different thermal expansion coefficients of the primary packaging components. Importantly, this type of temporary breach in CCI frequently reseals itself when the vial is brought back to ambient temperature. The following study illustrates a CCI test method for identifying both temporary and permanent defects in vial assemblies exposed to cryogenic storage conditions using laser-based headspace oxygen analysis. The method takes advantage of the nitrogen-enriched environment that exists in most cryogenic storage conditions. When vials are placed into cryogenic storage, the cold temperature creates a pressure gradient across the vial seal that, if a leak defect develops, drives nitrogen gas into the vial headspace and, thereby, decreases the headspace oxygen concentration for vials originally packaged with an air headspace. This decrease in headspace oxygen after the cryogenic storage period can be used to identify a breach in CCI, regardless of whether the defect is temporary or permanent. Experimental data obtained for three different vial types (a 2R glass vial, a 2 mL plastic CZ vial, and a 2 mL plastic Aseptic Technologies (AT) vial) demonstrated that this CCI test method can robustly and readily detect laser-drilled micron-sized positive controls down to 5 μm (the smallest defect size tested) in the body of the vial and type controls prepared using a Ø64 μm wire at the stopper-seal interface (effective defect size varied depending on the vial).

Antioxidant potential of olive leaf (<i>Olea europaea</i> L.) sustainable extracts evaluated <i>in vitro</i> and minced beef meat

In this work, by using water steam only, two antioxidant extracts were obtained from olive leaves (Olea europaea L.), a by-product of olive oil chain. Olive leaf extracts (OLEs) were tested as such (water extract: WE) and partially purified with ethyl acetate (ethyl acetate [EA] extract). Total phenols were 7.4 mg/mL and 3.8 mg/mL in WE and EA final solutions, respectively, evidencing a different composition by high-performance liquid chromatography analysis. Both extracts were evaluated in vitro in comparison to pure hydroxytyrosol (Hy). A 2,2-diphenyl-1-picrylhydrazyl (DPPH) EC50 of 57.6, 76.5, and 39.7 µg/mL and a ferric reducing antioxidant power EC50 of 84.8, 69.9, 41.2 µg/mL were determined for WE, EA, and Hy solution, respectively. The Rancimat induction time determined at 120°C in a lard sample with 200-ppm total phenol equivalent addition of WE, EA, and Hy was 8.92 h, 12.74 h, and 7.27 h, respectively (vs. 2.24 h for lard only). Extracts were added at the same dose (200 ppm) to minced beef patties that were put in closed containers under controlled air headspace composition (NA, natural air; HOA, modified air with 80% O2; and 20% N2) and stored at 4°C up to 10 days. Extracts showed significant effectiveness in contrasting decrease of O2 level in containers as well as pH and color changes of patties. A significant increase (expressed as mg of malondialdehyde MDA/kg; thiobarbituric acid-reactive substance (TBARS) assay was conducted in control samples at an interval of 0–10 days (from 0.52 to 0.78 mg of MDA/kg in NA samples; and from 0.55 to 1.31 mg of MDA/kg in HOA samples), while minimal changes were observed in treated samples. These findings suggest a potential use of OLEs for maintaining quality and oxidative stability of beef patties during storage.

Heat transfer within a multi-package: Assessing the impact of package design on the cooling of strawberries

Perishable horticultural products may necessitate multi-packaging for preservation. The optimized primary and secondary packaging designs allow to reduce cooling time and ensure uniform product temperature, thereby enhancing fruit quality. This study examined how the secondary package design impacts the cooling of strawberries in airtight clamshells (AC) during precooling. The AC design simulates heat transfer within Modified Atmosphere Package (MAP) where there is no direct interaction between the external cooling air and the internal environment of the clamshell. Laboratory experiments were conducted to simulate one level of a pallet, using artificial material instead of real strawberries in order to have a better control of thermophysical properties and thus to better investigate heat transfer mechanisms. The thermal performance of an existing tray design was compared to three new alternative designs. The effect of air headspace, vent holes area and inlet airflow rate on the cooling efficiency was investigated.Experimental results revealed significant cooling heterogeneities among different AC positions, with the largest observed disparities being 1.8 h for half cooling time (HCT) and 3.7 h for seven-eight cooling time (SECT) in the current tray design. Incorporating vent holes into the current commercialized tray design demonstrated superior cooling performance, with 8% improvement of the overall average HCT. Analysis showed increasing the thickness of the air headspace above the AC increased 91% and 113% the overall average HCT and SECT, respectively. The research found that airflow distribution in a tray has a critical effect on the heat transfer between the AC walls and the surrounding air temperature. Thus, the packaging design is crucial in ensuring proper ventilation around the ACs.The alternative designs or operating under a lower airflow rate revealed a potential to cut down on energy use for ventilation. Specifically, when the airflow rate was reduced by one-quarter, there was a remarkable 94% decrease in energy usage. However, this benefit is counterbalanced by a 100% increase in the overall average HCT, which might adversely affect the product quality. Hence, optimizing the packaging design is essential to ensure the right balance between energy efficiency and product quality.The HCT exhibited a linear correlation with the external resistance, which is influenced by the airflow behavior, whatever the AC positions and tray designs.

Plant–plant communication in Camellia japonica and C. rusticana via volatiles

Plants emit volatile compounds when they are subjected to herbivorous, pathogenic, or artificial damages. Both the damaged plant and the neighboring intact plants induce resistance when they receive these volatiles, a phenomenon known as plant–plant communication. However, field observations of this phenomenon are limited. To understand the nature of plant–plant communication, we collected information about intra- and inter-plant signaling via volatiles in Camellia japonica and C. rusticana under natural conditions. We exposed intact branches of damaged plant (intra-plant) or neighboring plant (inter-plant) to artificially damaged plant volatiles (ADPVs). Leaf damage reduced in ADPVs-exposed branches in the neighboring plants compared to branches that were exposed to volatiles from intact leaves, thus, indicating that inter-plant signaling occur by the emission of volatiles from damaged leaves. We also conducted an air-transfer experiment wherein the headspace air of the damaged branch was transferred to the headspace of intact branches. Leaf damage reduced on the ADPVs-transferred branch compared to the control branch. The effect of volatiles on damage reduction lasted for three months. Our results indicate that ADPVs in Camellia species contain cues that induce resistance in neighboring plants. Our findings improve understanding of plant defense strategies that may be used in horticulture and agriculture.

Volatile organic compounds in headspace characterize isolated bacterial strains independent of growth medium or antibiotic sensitivity.

Early and reliable determination of bacterial strain specificity and antibiotic resistance is critical to improve sepsis treatment. Previous research demonstrated the potential of headspace analysis of volatile organic compounds (VOCs) to differentiate between various microorganisms associated with pulmonary infections in vitro. This study evaluates whether VOC analysis can also discriminate antibiotic sensitive from resistant bacterial strains when cultured on varying growth media. Both antibiotic-sensitive and -resistant strains of Pseudomonas aeruginosa, Staphylococcus aureus and Klebsiella pneumonia were cultured on 4 different growth media, i.e. Brain Heart Infusion, Marine Broth, Müller-Hinton and Trypticase Soy Agar. After overnight incubation at 37°C, the headspace air of the cultures was collected on stainless steel desorption tubes and analyzed by gas chromatography time-of-flight mass spectrometry (GC-tof-MS). Statistical analysis was performed using regularized multivariate analysis of variance and cross validation. The three bacterial species could be correctly recognized based on the differential presence of 14 VOCs (p<0.001). This discrimination was not influenced by the different growth media. Interestingly, a clear discrimination could be made between the antibiotic-resistant and -sensitive variant of Pseudomonas aeruginosa (p<0.001) based on their species-specific VOC signature. This study demonstrates that isolated microorganisms, including antibiotic-sensitive and -resistant strains of Pseudomonas aeruginosa, could be identified based on their excreted VOCs independent of the applied growth media. These findings suggest that the discriminating volatiles are associated with the microorganisms themselves rather than with their growth medium. This study exemplifies the potential of VOC analysis as diagnostic tool in medical microbiology. However, validation of our results in appropriate in vivo models is critical to improve translation of breath analysis to clinical applications.

Rapid Method of Wastewater Classification by Electronic Nose for Performance Evaluation of Bioreactors with Activated Sludge.

Currently, e-noses are used for measuring odorous compounds at wastewater treatment plants. These devices mimic the mammalian olfactory sense, comprising an array of multiple non-specific gas sensors. An array of sensors creates a unique set of signals called a "gas fingerprint", which enables it to differentiate between the analyzed samples of gas mixtures. However, appropriate advanced analyses of multidimensional data need to be conducted for this purpose. The failures of the wastewater treatment process are directly connected to the odor nuisance of bioreactors and are reflected in the level of pollution indicators. Thus, it can be assumed that using the appropriately selected methods of data analysis from a gas sensors array, it will be possible to distinguish and classify the operating states of bioreactors (i.e., phases of normal operation), as well as the occurrence of malfunction. This work focuses on developing a complete protocol for analyzing and interpreting multidimensional data from a gas sensor array measuring the properties of the air headspace in a bioreactor. These methods include dimensionality reduction and visualization in two-dimensional space using the principal component analysis (PCA) method, application of data clustering using an unsupervised method by Density-Based Spatial Clustering of Applications with Noise (DBSCAN) algorithm, and at the last stage, application of extra trees as a supervised machine learning method to achieve the best possible accuracy and precision in data classification.

Development of an antimicrobial packaging system for fresh cape gooseberry (Physalis peruviana L.) fruits

An active antifungal packaging system combined with modified atmospheres (MAP) was proposed to preserve cape gooseberry. Initially, the antifungal effect of oregano essential oil, cinnamaldehyde, and 2-nonanone in the vapor phase was evaluated in vitro to determine the minimum inhibitory concentration (MIC) for Botrytis cinerea. Next, the better antifungal compound was included inside an active packaging system adsorbed in powdered bentonite. 100 ± 1 g of fruits were introduced in sealed polylactic acid (PLA) packages with a 0.058 mm perforation in the center forming a MAP and stored at 6 °C and 75 % RH determining fungal deterioration and changes in quality properties. From the in vitro tests, it was determined that cinnamaldehyde was the component with the highest antifungal capacity with a MIC of 2,38 µg per cm3 of headspace air. With the active packages combined with MAP, it was possible to obtain up to 42 days of shelf life.

Low CO2 partial pressure steers CHO cells into a defective metabolic state.

The accumulation of carbon dioxide during large-scale culture of animal cells brings adverse effects, appropriate aeration strategies alleviate CO2 accumulation while improper reactor operation may lead to the presence of low CO2 partial pressure (pCO2) condition as occurs in many industrial cases. Thus, this study aims to reveal the in-depth influence of low pCO2 on Chinese Hamster Ovary (CHO) cells for providing a reference for design space determination of CO2 control with regard to the Quality by Design (QbD) guidelines. The headspace air over purging caused the ultra-low pCO2 (ULC) where the monoclonal antibody production as well as the aerobic metabolic activity were reduced. Intracellular metabolomics analysis indicated a less efficient aerobic glucose metabolic state under ULC conditions. Based on the increase of intracellular pH and lactate dehydrogenase activity, the shortage of intracellular pyruvate could be the cause of the deficient aerobic metabolism, which could be partially mitigated by pyruvate addition under ULC conditions. Finally, a semi-empirical mathematical model was used to better understand, predict and control the occurrence of extreme pCO2 conditions during the cultures of CHO cells. Low pCO2 steers CHO cells into a defective metabolic state. A predictive relation among pCO2, lactate, and pH control was applied to get new insights into CHO cell culture for better and more robust metabolic behavior and process performance and the determination of QbD design space for CO2 control.

A gravity-independent single-phase electrode reservoir for capillary electrophoresis applications.

Capillary electrophoresis (CE) holds great promise as an in situ analytical technique for a variety of applications. However, typical instrumentation operates with open reservoirs (e.g., vials) to accommodate reagents and samples, which is problematic for automated instruments designed for space or underwater applications that may be operated in various orientations. Microgravity conditions add an additional challenge due to the unpredictable position of the headspace (air layer above the liquid) in any two-phase reservoir. One potential solution for these applications is to use a headspace-free, flow-through reservoir design that is sealed and connected to the necessary reagents and samples. Here we demonstrate a flow-through HV reservoir for capillary electrophoresis that is compatible with automated in situ exploration needs, and which can be electrically isolated from its source fluidics (in order to prevent unwanted leakage current). We also demonstrate how the overall system can be rationally designed based on the operational parameters for CE to prevent electrolysis products produced at the electrode from entering the capillary and interfering with the CE separation. A reservoir was demonstrated with a 19 mm long, 1.8 mm inner diameter channel connecting the separation capillary and the HV electrode. Tests of these reservoirs integrated into a CE system show reproducible CE system operation with a variety of background electrolytes at voltages up to 25 kV. Rotation of the reservoirs, and the system, showed that their performance was independent of the direction of the gravity vector. This article is protected by copyright. All rights reserved.

Stopper Movement and Headspace (Air Bubble Size) Limitations for 2.25mL Prefilled Syringe.

The Sterile Barrier is one of the most important aspects of the Container Closure Integrity (CCI) for a prefilled syringe (PFS or syringe). This crucial barrier enables the protection of the syringe contents from contamination. The plunger stopper (stopper) is naturally in a stationary position that is controlled by the static friction between the plunger stopper and the syringe barrel wall. When an applied force is greater than the static friction which is commonly known as the Break Loose force, the plunger stopper will move. This movement can occur when the pressure differential between the gaseous headspace inside the syringe and the external atmosphere is large enough that the force exerted on the stopper exceeds the Break Loose force of the syringe. This can occur during altitude or temperature changes incurred during aerial or mountainous transport. In such conditions, the stopper movement can further be increased if an air bubble is introduced between the liquid fill in the syringe and the stopper during the stoppering process. This paper, therefore, discusses the relationship between stopper movement and initial headspace (air bubble size/ABS) in a 2.25mL Type I glass syringe using theoretical and empirical approaches. The results showed the maximum initial headspace needed to enable CCI at specified altitudes and plunger stopper movements for the syringe-plunger stopper combination used in the study. Empirical data also indicated that CCI can be maintained for this syringe-plunger stopper combination with up to 9mm initial headspace at altitudes up to 17,000 feet.

Can nonvolatile tastants be smelled during food oral processing?

While accumulating evidence implied the involvement of retro-nasal sensation in the consumption of nonvolatile taste compounds, it is still unclear whether it was caused by the taste compounds themselves, and if so, how can they migrate from the oral to nasal cavity. At first, we proposed aerosol particles as an alternative oral-nasal mass transfer mechanism. The high-speed camera approved that aerosol particles could be generated by the typical oral and pharynx actions during food oral processing; while the narrow-band imaging of nasal cleft and mass spectrometry of nostril-exhaled air approved the migration of aerosol within the oral-nasal route. Then, the "smelling" of taste compounds within the aerosol particles was testified. The four-alternative forced choices (4AFC) approved that the potential volatile residues or contaminants within the headspace air of pure taste solution cannot arouse significant smell, while the taste compounds embedded in the in vitro prepared aerosol particles can be "smelled" via the ortho route. The "smell" of sucrose is very different from its taste and the "smell" of quinine, implying its actual olfaction. The sweetness intensity of sucrose solution was also reduced when the volunteers' noses were clipped, indicating the involvement of retro-nasal sensation during its drinking. At last, the efficiency of aerosol as a mechanism of oral-nasal mass transfer was demonstrated to be comparable with the volatile molecules under the experimental condition, giving it the potential to be a substantial and unique source of retro-nasal sensation during food oral processing.

Ultrasound Contrast Stability for Urinary Bladder Pressure Measurement.

The goal of this study was to evaluate ultrasound contrast microbubbles(MB) stability during a typical cystometrogram(CMG) for bladder pressure measurement application using the subharmonic-aided pressure estimation technique. A detailed study of MB stability was required given two unique characteristics of this application: first, bulk infusion of MBs into the bladder through the CMG infusion system, and second, duration of a typical CMG which may last up to 30 min. To do so, a series of size measurement and contrast-enhanced ultrasound imaging studies under different conditions were performed and the effects of variables that we hypothesized have an effect on MB stability, namely, i) IV bag air headspace, ii) MB dilution factor, and iii) CMG infusion system were investigated. The results verified that air volume in intravenous(IV) bag headspace was not enough to have a significant effect on MB stability during a CMG. We also showed that higher MB dosage results in a more stable condition. Finally, the results indicated that the CMG infusion system adversely affects MB stability. In summary, to ensure MB stability during the entire duration of a CMG, lower filling rates(limited by estimated bladder capacity in clinical applications) and/or higher MB dosage(limited by FDA regulations and shadowing artifact) and/or the consideration of alternative catheter design may be needed.

Rapid changes in profiles from stored materials used in scent training of explosive detection dogs

Canines trained on scents from materials emitting vapours of explosives and related compounds are widely used to detect explosives in civilian, military and forensic applications. Despite the importance of these training materials, there is limited knowledge on how long these subsamples can be stored and whether vapour profiles change over time. We developed a sampling methodology that makes use of a secondary chamber for stabilisation of headspace concentration to allow reliable and reproducible determination of scent profiles. The effect of aging was investigated by following the response of volatile markers emitted from eight common explosives in open and closed containers over two months or two years. The initial headspace air volume consisted of a wide variety of chemical substances related to explosives, with levels varying in magnitude from low ppb to ppm. All included subsamples were affected by aging by demonstrating exponentially lower levels, and five subsamples showed a significant change in their scent profile. The dominant components decreased on a short time scale for plastic explosives based on RDX, PETN and dynamite as well as for granules of octol and ammonium nitrate mixed with fuel. For flakes of TNT, granules of Comp B and nitrocellulose powder, headspace air concentrations declined, but the overall character of their profiles were in general more stable. The overall changes, i.e., lower levels and/or changed profiles, justifies regular checks of the scent status of training materials. Considering these results together with data displaying marginal changes in energetic performance, it is advisable to complement scent training with training materials subjected to different durations of aging.

New tool for Gram-negative and Gram-positive bacterial strains differentiation through GCMS direct identification of exogenous VOC metabolites in headspace vials

In this paper, a chromatographic method for the determination of volatile organic compounds (VOCs) as a tool for Gram-positive and Gram-negative bacterial strains identification was described. Direct Headspace gas chromatography coupled with mass spectrometry (Headspace-GC-MS) has been used for the qualitative determination of VOCs emitted by certain bacterial strains (Salmonella Typhimurium, Escherichia coli, Serratia rubidae, Staphyloccocus aureus, Enterococcus casseliflavus, and Enterococcus faecalis). In the first stage of the study, pathogenic bacteria were cultured in broth-specific liquid culture medium directly (lauryl sulfate broth) into headspace vials. Subsequently, the VOC emissions were analyzed by airborne screening in the headspace vials. Thus, the objective was to analyze all the resulting volatile organic compounds in order to select only those compounds, which can be exclusively associated with specific pathogenic bacteria. Qualitative analysis by Headspace-GC-MS has proven to be a non-invasive, accurate, and fast method for identifying certain bacterial strains, based on VOCs emission. A considerable number of volatile organic compounds have been determined in the headspace air, a significant difference being observed between the VOCs emitted by bacterial cultures compared to the culture medium but also between the types of bacterial cultures themselves. The study presents preliminary results, which prove that the identification of the studied pathogenic bacteria is possible, based on the determination of certain types of VOCs in the headspace air of these cultures. This method can be used successfully for the rapid identification of bacterial culture types compared to classical methods.

The Apparent Respiratory Quotient of Soils and Tree Stems and the Processes That Control It

AbstractThe CO2/O2 fluxes ratio (apparent respiration quotient [ARQ]) measured in soils and plants contains valuable information about the respiratory‐substrate stoichiometry and biotic and abiotic non‐respiratory processes. We investigated ARQ variability by measurements in soil pore space air, and in headspace air from incubations of bulk‐soil and tree stem tissues (both fresh and 24‐hr stored tissues) in 10 measurement campaigns over 15 months in a Mediterranean oak forest. Mean (range) ARQ values were: soil air, 0.76 (0.60–0.92); bulk soil, 0.75 (0.53–0.90); fresh stem tissues, 0.39 (0.19–0.70); and stored stem tissues, 0.68 (0.42–1.08). The variability in tree stems was assumed to be controlled by CO2 re‐fixation that lowered ARQ from 1.0, the value expected for carbohydrate respiration in plants. We estimate that the values of the stored tissues represent better stem metabolism since the fresh‐tissue results contained a signal of wound‐response O2 uptake that further lowered ARQ. The mean bulk‐soil ARQ (0.75) was considerably lower than expected by soil organic matter (SOM) stoichiometry (0.95). This lower value might represent the stoichiometry of the SOM sub‐pool that supports respiration, and/or oxidative depolymerization that increases O2 fluxes. Abiotic O2 uptake was demonstrated to reduce bulk‐soil ARQ down to 0.37 and consume Fe2+, but estimated to have small effect under typical respiration rates. Soil‐air ARQ was usually higher than bulk‐soil ARQ and lower than root ARQ (which, when measured, ranged from 0.73 to 0.96), demonstrating the potential of ARQ to partition the autotrophic and heterotrophic sources of soil respiration. The limitations of this partitioning method are discussed.

Effect of headspace air conditions on total organic acids dissolved in transformer oil

The aim of this work was studying the effect of dissolved oxygen concentration, temperature and humidity level of headspace air on the acidification of insulation oil. The novelty is assessment and classification of those parameters based on the acidity level, induction time and the rate of oil acidifying. Two gas-washers containing insulation oil and deionised water were in contact with the bubbling streams of O2/N2 containing different humidity levels. The acidity of two phases was determined based on TAN number and pH values, respectively. The results revealed that O2/N2 weight ratio, insulator temperature and the level of air humidity control the acidity strength, the induction time of acid production and the rate of oil acidifying, respectively. Reduction of O2/N2 weight ratio in the headspace air decreased the level of the produced organic acids, while reduction of temperature extended the onset time of acid formation. [Received: July 31, 2020; Accepted: January 12, 2021]

Impact of partially submersed iron scraps in simultaneously sulfate and nitrate removal using sulfate-reducing bacteria

In this study, partially submerged iron scraps were allowed to react to the contaminants at the headspace air and liquid interface for pollutants removal in the serum bottle reactors. The experiments were conducted using Box–Behnken design of Response Surface Methodology in anaerobic batch reactors (120 ml) at different concentrations of sulfate (0.5, 1.75, 3 g/L), nitrate (0.25, 0.375, 0.5 g/L) and iron scraps (0, 0.125, 0.250 g/50 ml). The sulfate reducer enriched mixed culture was used for simultaneous removal of SO42− and NO3−. The highest sulfate removal of 49.37 % was achieved at 0 g/50 ml ISs, 3 g/L SO4−2, and 0.375 g/L NO3−. Even at a higher concentration of both SO42− (3 g/L) and NO3−(0.5 g/L), a significant SO42− removal of 44.65% was achieved at an iron concentration of 125mg/50ml accompanied with NO3− conversion. Both the lower and higher concentrations of iron scraps were showing effective interaction at higher SO42− and NO3− levels. The results of the confirmatory experiments with iron scraps of 0.039 g/50 ml with the desirability of 0.92 showed a maximum SO42− removal of 50.62 % with complete conversion of nitrate.

The investigation of the volatile metabolites of lung cancer from the microenvironment of malignant pleural effusion

For malignant pleural effusions, pleural fluid cytology is a diagnostic method, but sensitivity is low. The pleural fluid contains metabolites directly released from cancer cells. The objective of this study was to diagnose lung cancer with malignant pleural effusion using the volatilomic profiling method. We recruited lung cancer patients with malignant pleural effusion and patients with nonmalignant diseases with pleural effusion as controls. We analyzed the headspace air of the pleural effusion by gas chromatography-mass spectrometry. We used partial least squares discriminant analysis (PLS-DA) to identify metabolites and the support vector machine (SVM) to establish the prediction model. We split data into a training set (80%) and a testing set (20%) to validate the accuracy. A total of 68 subjects were included in the final analysis. The PLS-DA showed high discrimination with an R2 of 0.95 and Q2 of 0.58. The accuracy of the SVM in the test set was 0.93 (95% CI 0.66, 0.998), the sensitivity was 83%, the specificity was 100%, and kappa was 0.85, and the area under the receiver operating characteristic curve was 0.96 (95% CI 0.86, 1.00). Volatile metabolites of pleural effusion might be used in patients with cytology-negative pleural effusion to rule out malignancy.

Identification of Volatile Sulfur Compounds Produced by Schizophyllum commune.

Schizophyllum commune is a causative agent of allergic bronchopulmonary mycosis, allergic fungal rhinosinusitis, and basidiomycosis. Diagnosis of these diseases remains difficult because no commercially available tool exists to identify the pathogen. Unique volatile organic compounds produced by a pathogen might be useful for non-invasive diagnosis. Here, we explored microbial volatile organic compounds produced by S. commune. Volatile sulfur compounds, dimethyl disulfide (48 of 49 strains) and methyl ethyl disulfide (49 of 49 strains), diethyl disulfide (34 of 49 strains), dimethyl trisulfide (40 of 49 strains), and dimethyl tetrasulfide (32 of 49 strains) were detected from headspace air in S. commune cultured vials. Every S. commune strain produced at least one volatile sulfur compound analyzed in this study. Those volatile sulfur compounds were not detected from the cultures of Aspergillus spp. (A. fumigatus, A. flavus, A. niger, and A. terreus), which are other major causative agents of allergic bronchopulmonary mycosis. The last, we examined H2S detection using lead acetate paper. Headspace air from S. commune rapidly turned the lead acetate paper black. These results suggest that those volatile sulfur compounds are potent targets for the diagnosis of S. commune and infectious diseases.

Sensing Methanol in Hand Sanitizers

Introduction The global health emergency due to the infectious respiratory disease SARS-CoV-2 or COVID-19 has rapidly increased the need for hand sanitizers. Public awareness about safety issues in hand sanitizers has emerged since the FDA placed a warning for 221 products (by Dec. 17, 2020) [1] that contained up to 81 vol% of toxic methanol, drastically exceeding recommended [2] limits (0.063 vol%). The ingestion of methanol-contaminated sanitizers led already to more than 700 fatalities in Iran [3] and the U.S.A. [4] since Feb. 2020. Therefore, low-cost and portable methanol detectors are needed to assist distributors, local authorities and even consumers to check product safety.Gas or liquid chromatography are most established for methanol detection in complex mixtures, but these are bulky, expensive instruments that require trained personnel, usually available only in specialized laboratories and unsuitable for on-site analyses. Cheaper, more compact and less power consuming are chemical gas sensors (e.g. Pt-loaded tungsten nitride [5] or nanoporous Al2O3-coated carbon nanotubes [6]) that detect methanol from the headspace of liquids. However, most are interfered by ethanol that is usually present at high content and none has been tested on hand sanitizers.Here, we present an inexpensive and compact device that quantifies hazardous methanol accurately in hand sanitizers by headspace analysis. We applied it to pure and methanol-spiked (0.01 – 90 vol%) commercial hand sanitizers with various compositions and compared to established gas chromatography. Method The handheld detector [7] features a separation column [8] (150 mg Tenax TA packed bed) placed ahead of a chemoresistive sensors based on flame-made Pd-doped SnO2 nanoparticles [9]. A vane pump provided the flow for sampling sanitizer headspace air and recovery. A microcontroller provided the required heating power to operate the sensor at 350 °C [9], monitored its resistance and communicated data wirelessly to a smartphone by Bluetooth or Wi-Fi. Results and Conclusions Hand sanitizers are complex mixtures containing usually ethanol, 1-/2-propanol but also humectants, odorants, denaturants and colorants. Thus, the device was evaluated on the headspace of six commercially available hand sanitizers with different compositions. When spiked with 0.01 – 90 vol% methanol (total 66 samples) to simulate the entire range of typical contamination/adulteration, the sensor quantified these concentrations accurately with high R2 of 0.99 compared to “gold standard” gas chromatography (Figure 1). More specifically, methanol concentrations at the FDA limit (0.063 vol%) were determined between 0.051 – 0.073 vol%, which should be sufficient for screening hand sanitizers. Importantly, other compounds, colorants and even gel-like viscosity did not interfere highlighting the robustness of the present device.We anticipate this device to be helpful to police, customs, distributors and consumers to check product safety. It is compact (2×4×12 cm3), weighs only 94 g and offers low power consumption (ca. 1.1 W during analysis) enabling battery-driven operation. The operation and data display are user-friendly by providing wireless communication by Wi-Fi. When combined with a breath sampler, this device is even applicable for medical screening of methanol poisoning by breath analysis [10], as established for ethanol by law enforcement [11].