Polyacrylate Fiber Research Articles

Measuring bioconcentration factors of sediment-associated fipronil in Lumbriculus variegatus using passive sampling techniques

Fipronil and its degradates have been detected ubiquitously in aquatic environment worldwide, yet little is known about its bioaccumulation potential. The goal of the present study was to measure bioconcentration factor (BCF) of sediment-associated fipronil in a benthic invertebrate, Lumbriculus variegatus using passive sampling techniques. Three passive samplers including polymethyl methacrylate (PMMA) film, poly(dimethylsiloxane) fiber and polyacrylate fiber were evaluated. PMMA film was identified as the preferred method and was applied to determine fipronil log KOC (3.77 ± 0.04). BCF of sediment-associated fipronil in L. variegatus was obtained through measuring freely dissolved concentration (Cfree). Because fipronil degraded in sediment, time weighted average (TWA) Cfree was estimated for calculating BCFTWA (1855 ± 293 mL/g lipid). Fipronil BCF was also measured in a water-only bioaccumulation test of L. variegatus under constant exposure condition. This BCF value (1892 ± 76 mL/g lipid) was comparable with the BCFTWA, validating effectiveness of the passive sampling method for the measurement of sediment Cfree. Fipronil was bioaccumulative in L. variegatus according to the USEPA’s criteria. The combination of Cfree and TWA concentration measurements was demonstrated to properly determine BCF value for moderately hydrophobic and degradable chemicals in sediment.

A Novel Water-Swelling Sampling Probe for in Vivo Detection of Neonicotinoids in Plants.

Ecotoxicological risks of neonicotinoid insecticides are raising significant concerns, including their potential role in bee population declines. Neonicotinoids are water-soluble, systemic insecticides, and exposure of nontarget organisms such as pollinators occurs mainly through residues in nectar and pollens of flowering plants. To better elucidate the underlying mechanisms for such nontarget exposure, it is highly valuable to develop analytical capabilities for in vivo monitoring of neonicotinoids in live plants. In this study, we developed a novel biomimetic water-swelling solid-phase microextraction (SPME) probe, with limits of detection for neonicotinoids as low as 0.03 ng mL-1, and applied it for in vivo detection of seven neonicotinoids in plant sap. The preparation of this fiber was simple and free of stringent or complex physical-chemical reactions. Equilibrium in neonicotinoid accumulation on the fiber was reached in <10 min, allowing for near instantaneous sampling. The water-swelling fiber displayed much greater sampling capacity than the commercially available polydimethylsiloxane and polyacrylate fibers, good reproducibility (RSD of inter- and intrafiber <8.9% and 7.8%, respectively), and antibiofouling property (no loss in performance after 20 use cycles). After treating lettuce (Lactuca sativa L.) by foliar spray and soybean (Glycine max M.) by seed soaking, the in vivo assays provided a wealth of information, including changes in levels and distribution of neonicotinoids over time in the same plants. Kinetics and distribution patterns suggested that after treatment at the same level, neonicotinoids differed significantly in their levels in the sap. The in vivo sampling and monitoring of neonicotinoids in live plants may provide unique and much needed information in achieving breakthrough understanding of the connection between neonicotinoid use and pollinator exposure.

Durable molybdenum oxide coated solid-phase microextraction fiber for highly selective and efficient extraction of polycyclic aromatic hydrocarbons in water.

A bonding method was developed for coating molybdenum oxides onto a steel wire substrate, which was used as a solid-phase microextraction fiber, was coupled with gas chromatography. Based on the characterization, it is found that the as-prepared molybdenum oxides material contained a nanobelt structure with a uniform size and good dispersibility. In addition, there were a large number of small protrusions on the surface of the nanobelts. These characteristics provided a large specific surface area for extraction. Molybdenum oxides exhibited a high extraction selectivity for polycyclic aromatic hydrocarbons owing to its moderate coordination. After the optimization of the factors, method detection limits of<1.25 μg/L were achieved, and the calibration curves were linear within the range of 2-600 μg/L. In addition, repeatability was demonstrated, and the relative standard deviation<6.4%. The molybdenum oxides coating had a high scratch resistance, which could effectively prevent coating wear and failure. Combined with the high thermal and chemical stability, the service life of the coating was improved and could be used 150 times without a significant reduction in the extraction performance. Finally, the as-prepared fiber had a comparable extraction capacity and higher partition coefficients that those of commercial polyacrylate fibers.

Zwitterionic polymeric ionic liquid-based sorbent coatings in solid phase microextraction for the determination of short chain free fatty acids

Five different zwitterionic sorbent coatings based on polymeric ionic liquids (PILs) were developed by the on fiber UV co-polymerization of the zwitterionic monomers 1-vinyl-3-(alkylsulfonate)imidazolium or 1-vinyl-3-(alkylcarboxylate)imidazolium and different dicationic ionic liquid (IL) crosslinkers. The developed sorbent coatings were applied in headspace solid-phase microextraction in combination with gas chromatography-mass spectrometry for the determination of short chain free fatty acids in wine. The sorbent coatings were found to extract these analytes via a non-competitive extraction mechanism. The methodology was optimized for the two best zwitterionic PIL coatings and compared to the commercially-available carboxen/polydimethylsiloxane (CAR/PDMS) and polyacrylate (PA) fibers. The sorbent coating based on the 1-vinyl-3-(propanesulfonate)imidazolium IL (Fiber 1) was more sensitive than PA while providing similar limits of detection to CAR/PDMS for the determination of analytes in a diluted synthetic wine sample. At the same time, Fiber 1 required lower extraction times (only 20 min versus 60 min for CAR/PDMS and 40 min for PA), exhibited higher reproducibility (with relative standard deviation lower than 8.9% for a spiked level of 7 µM) and was more tolerant to ethanol present within the sample. The zwitterionic PILs were also applied for the analysis of red wine, and the results were in agreement with those obtained for CAR/PDMS. The analytes were detected and quantified in the concentration range from 0.18 ± 0.03 mg L−1 to 4.8 ± 0.9 mg L−1, depending on the analyte and fiber.

Optimization of a DI-SPME-GC–MS/MS method for multi-residue analysis of pesticides in waters

This paper discusses the optimization and validation of a complete and simple method for the simultaneous determination of 48 pesticides in water by combining direct immersion solid-phase micro-extraction (DI-SPME) and gas chromatography-ion trap tandem mass spectrometry (GC-ITMS/MS). For the extraction, the different SPME parameters were tested and optimized. As a result, the polyacrylate fiber (PA 85 μm) was selected in direct immersion mode; the extraction temperature was set to 60 °C with an extraction time of 45 min and a stirring speed of 500 rpm; the thermal desorption time of the fiber in the injector port was fixed to 10 min at 275 °C. Concerning the analysis, MS/MS parameters were optimized and figures of merit were compared. Later, the method was validated and showed good linearity in the concentration ranging from 0.05 to 100 μg L−1. The reproducibility of measurements expressed as the relative standard deviation (% RSD) was found to be satisfactory. Furthermore, the detection limits for all the compounds were between 0.001 and 0.458 μg L−1, except for methomyl and hexachlorobenzene (1.09 and 0.99 μg L−1 respectively). Finally, the proposed DI-SPME-GC–MS/MS method was tested successfully for water samples collected along the watershed of Abou Ali River (North Lebanon).

Solid-phase microextraction of antibiotics from fish muscle by using MIL-101(Cr)NH2-polyacrylonitrile fiber and their identification by liquid chromatography-tandem mass spectrometry

Antibiotics are a group of antibacterial drugs used in the treatment and prevention of bacterial diseases in humans, veterinary animals, and farmed fish. Inappropriate and excessive use of antibiotic therapy leads to antibiotic fragment in the water bodies thus affect the aquatic organisms. In this study, an amino group modified high surface area metal-organic framework (MOF) MIL-101(Cr)-NH2 was used to prepare solid-phase microextraction (SPME) fiber to detect four different classes (total 6 ABs) of antibiotics for the first time from living tilapia fish (Oreochromis mossambicus) by coupling SPME with high performance liquid chromatography-tandem mass spectrometry (LC-MS/MS). The extraction efficiencies of the custom-made fiber were superior as compared with the commercial C18, polydimethylsiloxane (PDMS), PDMS/divinylbenzene (DVB) and polyacrylate fibers. The custom-made fiber also exhibited excellent reproducibility with the low intra-fiber relative standard deviations (RSDs 1.5%–8.3%) and inter-fiber RSDs (7.3%–14.5%), which made it ideal for in vivo extraction in fish muscle. The as-prepared MIL-101(Cr)-NH2 fiber was then used to determine antibiotics in the dorsal-epaxial muscle of living fish. Comparing to the traditional solid-liquid extraction (SLE) method, the SPME method showed reduced invasiveness and higher sensitivity than the SLE method. In general, this study explored a convenient, cost-effective and highly sensitive SPME method based on amino modified MOF for in vivo antibiotic detection in fish muscle.

Impacts of Microplastics on the Soil Biophysical Environment.

Soils are essential components of terrestrial ecosystems that experience strong pollution pressure. Microplastic contamination of soils is being increasingly documented, with potential consequences for soil biodiversity and function. Notwithstanding, data on effects of such contaminants on fundamental properties potentially impacting soil biota are lacking. The present study explores the potential of microplastics to disturb vital relationships between soil and water, as well as its consequences for soil structure and microbial function. During a 5-weeks garden experiment we exposed a loamy sand soil to environmentally relevant nominal concentrations (up to 2%) of four common microplastic types (polyacrylic fibers, polyamide beads, polyester fibers, and polyethylene fragments). Then, we measured bulk density, water holding capacity, hydraulic conductivity, soil aggregation, and microbial activity. Microplastics affected the bulk density, water holding capacity, and the functional relationship between the microbial activity and water stable aggregates. The effects are underestimated if idiosyncrasies of particle type and concentrations are neglected, suggesting that purely qualitative environmental microplastic data might be of limited value for the assessment of effects in soil. If extended to other soils and plastic types, the processes unravelled here suggest that microplastics are relevant long-term anthropogenic stressors and drivers of global change in terrestrial ecosystems.

Evaluation of polypyrrole/silver/polyethylene glycol nanocomposite sorbent for electroenhanced direct-immersion solid-phase microextraction of carvacrol and thymol from medicinal plants

The unique features of nanostructured polypyrrole, conductivity enhancement effect of silver nanoparticles and high polar adsorptivity of polyethylene glycol were merged into polypyrrole/silver/polyethylene glycol (PPy/Ag/PEG) nanocomposite. It was synthesized and simultaneously coated on the surface of a stainless-steel fiber using an amended electropolymerization procedure. Before coating, the fiber substrate was made porous and sticky by allocating platinum dots on the surface of the stainless-steel fiber using the electrophoretic method. The prepared fiber was applied for the extraction of carvacrol and thymol (the most important antioxidants in medicinal plants) through an electroenhanced direct-immersion solid-phase microextraction (EE-DI-SPME) sampling strategy, followed by GC-FID quantification. To achieve the best efficiency, the effectual experimental variables including pH of sample solution, applied voltage, extraction temperature and time, stirring rate, and ionic strength were investigated. Under the optimal experimental conditions, the calibration curves were linear over the range of 0.5–30 µg mL−1 for thymol and 0.01–30 µg mL−1 for carvacrol. The detection limits (3Sb) and relative standard deviation (RSD%, n = 6) were obtained to be 0.15, 0.003 µg mL−1 and 10.2, 8.7% for thymol and carvacrol, respectively. The results demonstrated the priority of the proposed fiber compared with polypyrrole and polyacrylate fibers, in terms of extraction efficiency, durability and stability. The developed method was successfully employed for the analysis of thymol and carvacrol in medicinal plants.

Analysis of trace-level nitrated polycyclic aromatic hydrocarbons in water samples by solid-phase microextraction with gas chromatography and mass spectrometry.

A solid-phase microextraction coupled with gas chromatography and mass spectrometry method has been developed for the determination of ten nitrated polycyclic aromatic hydrocarbons in water samples. Five different kinds of commerical fibers were used to compare the extraction efficiency, including 65μm polydimethylsiloxane/divinylbenzene, 100μm polydimethylsiloxane, 30μm polydimethylsiloxane, 7μm polydimethylsiloxane, and 85μm polyacrylate fibers. Five factors were also selected to optimize conditions, including extraction temperature, time, stirring speed, salt concentration, and headspace volume. Taguchi design was applied to design the experiments and obtain the best parameters. The results show that 65μm polydimethylsiloxane/divinylbenzene fiber directly immersed into aqueous solution for 35min at 55°C with a constant stirring rate of 1150rpm were the optimal conditions. Under these conditions, the limits of quantification were 0.007-0.063μg/L, and the relative standard deviation based on six replicates ranged from 2.8 to 9.5%. The spiked recoveries ranged from 69.1 to 110.1%. Intra- and inter day relative standard deviations at three concentration levels were less than 12%, and the recoveries were 66.4-111.5%. The proposed method is reliable for analyzing nitrated polycyclic aromatic hydrocarbons in different water samples.

Restoring balance: biofilms and wound dressings.

Biofilms are responsible for stimulating and maintaining wound inflammation, increasing infection risk and delaying wound closure. Appropriate biofilm management is required to fight against local and systemic infection and to restore balance to the wound environment. The most effective way to remove biofilms involves the use of mechanical techniques, with the wound dressing representing an important component of this strategy. Wound dressing fibres, such as polyacrylate fibres, have been shown to be effective in affecting biofilm architecture by disrupting the biofilm matrix. This helps enhance the efficacy of antimicrobials, such as silver. Focusing an antibiofilm strategy on active agents alone does not constitute a sustainable approach to biofilm management. Furthermore, adding too many active chemicals into a wound can be highly detrimental to the wound bed, and potentially may have both short- and long-term biological concerns. Particular attention on the characteristics and key features of wound dressings is discussed in this paper. The aim of the paper is to review the ideal characteristics of wound dressings, in conjunction with antimicrobials, that are considered a fundamental part of an antibiofilm strategy and growing requirement for enhanced wound healing.

Expanding the use of polymeric ionic liquids in headspace solid-phase microextraction: Determination of ultraviolet filters in water samples

Three crosslinked polymeric ionic liquid (PIL) sorbent coatings were used in headspace solid-phase microextraction for the determination of a group of ultraviolet filters. The developed crosslinked PIL-based materials include two polycations and a double confined PIL. The method, in combination with gas chromatography-mass spectrometry, is simple, solvent free, and does not require of any derivatization step. After proper optimization of the methodologies with each developed fiber, the analytical performance was compared with a commercial polyacrylate fiber. A study of the normalized calibration slopes, obtained by dividing the calibration slope of each analyte by the coating volume, revealed that the crosslinked fibers can be used as alternatives to commercial fibers for the determination of the selected group of compounds. In particular, the coating nature of the PIL containing the 1-vinylbenzyl-3-hexadecylimidazolium bis[(trifluoromethyl)sulfonyl]imide IL as monomer and the 1,12-di(3-vinylbenzylimidazolium)dodecane bis[(trifluoromethyl)sulfonyl]imide IL as crosslinker is the most suitable for the extraction of the selected compounds despite their coating volume, being 3.6 times lower than the commercial polyacrylate fiber. For this fiber, wide linear ranges, correlation coefficients higher than 0.990, limits of detection ranging from 2.8 ng L−1 to 26 ng L−1 and relative standard deviations ranging from 2.5 to 15% were achieved. Finally, all proposed PIL-based fibers were applied towards the analysis of tap water, pool water and lake water, with the majority of the ultraviolet filters being detected and quantified in the last two types of samples.

Evaluation of the Influence of Extraction Conditions on the Isolation and Identification of Volatile Compounds from Cagaita (Eugenia dysenterica) Using HS‑SPME/GC-MS

The objective of this study was to explore the extraction and identification of volatile organic compounds (VOCs) present in cagaita fruit (Eugenia dysenterica). Parameters such as type of extraction fiber, agitation, extraction time and extraction temperature were investigated. Initially, the VOCs were extracted using headspace solid-phase microextraction. Then, the compounds were identified using gas chromatography coupled to mass spectrometry. Results revealed the presence of at least 26 different compounds and the polyacrylate (PA) fiber promoted the extraction of a larger number of VOCs. Regarding the PA fiber, the most efficient extraction was achieved using a 50 rpm agitation at 45 oC for 30 min. The majority were monoterpenes (34.64%) and esters (36.28%). An increase in the extraction temperature promoted the isolation of more VOCs when using carboxen/polydimethylsiloxane (CAR/PDMS) and divinylbenzene/carboxen/polydimethylsiloxane (DVB/CAR/PDMS) fibers. However, these fibers allowed the isolation of a smaller number of VOCs. The extraction time and agitation had no significant influence.

Adsorption of Metal Ions by Amidoxime-based Polyacrylic Fibers

Event Abstract Back to Event Adsorption of Metal Ions by Amidoxime-based Polyacrylic Fibers Anup Tuladhar1, Horng-Bin Pan1 and Chien M. Wai1* 1 University of Idaho, United States A new amidoxime-based polyacrylic fiber is synthesized from the acrylic yarn – cheap and commercially available raw material – by reacting with hydroxylamine followed by alkaline hydrolysis to prepare amidoxime [C(NH2) = NOH] and carboxylic (COOH) groups on the polymer strands. The adsorbent was characterized by infrared spectroscopy. FTIR study of the fiber after the lead adsorption experiment showed that the stretch of the N-O peak is distorted slightly and the COO¯ peak is red-shifted compared to the free adsorbent. The adsorption capacities of the fiber for different heavy metals were evaluated using a fixed volume of known concentration of the heavy metal salt solution with various amounts of the fiber at different temperatures. The adsorption capacity of lead (II) at room temperature is about 169.9 mg of lead per gram of the fiber. The rate of adsorption of lead ions in aqueous solution by the fiber adsorbent is rapid. The results also showed the pseudo-second-order model fits the experimental data very well with the correlation coefficient greater than 0.999. Keywords: Adsorption, acrylic fiber, Amidoxime-based Poly acrylic fiber, adsorbent, Lead, sorption Conference: National Organization for the Professional Advancement of Black Chemists and Chemical Engineers (NOBCChE) 45th Annual Conference , Orlando, Florida, United States, 17 Sep - 20 Sep, 2018. Presentation Type: Poster Presentation Topic: Analytical Chemsitry Citation: Tuladhar A, Pan H and Wai CM (2019). Adsorption of Metal Ions by Amidoxime-based Polyacrylic Fibers. Front. Chem. Conference Abstract: National Organization for the Professional Advancement of Black Chemists and Chemical Engineers (NOBCChE) 45th Annual Conference . doi: 10.3389/conf.fchem.2018.01.00057 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 19 Oct 2018; Published Online: 17 Jan 2019. * Correspondence: Prof. Chien M Wai, University of Idaho, Moscow, United States, cwai@uidaho.edu Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Anup Tuladhar Horng-Bin Pan Chien M Wai Google Anup Tuladhar Horng-Bin Pan Chien M Wai Google Scholar Anup Tuladhar Horng-Bin Pan Chien M Wai PubMed Anup Tuladhar Horng-Bin Pan Chien M Wai Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Selective and Efficient RNA Analysis by Solid-Phase Microextraction.

In this study, a solid-phase microextraction (SPME) method was developed for the purification of mRNA (mRNA) from complex biological samples using a real-time reverse transcription quantitative polymerase chain reaction (RT-qPCR) assay for quantification. The chemical composition of the polymeric ionic liquid (PIL) and a polyacrylate (PA) SPME sorbent coating was optimized to enhance the extraction performance. Of the studied SPME sorbent coatings, the PIL containing carboxylic acid moieties in the monomer and halide-based anions extracted the highest amount of mRNA from aqueous solutions, whereas the native PA fiber showed the lowest extraction efficiency. On the basis of RT-qPCR data, electrostatic interactions and an ion-exchange mechanism between the negatively charged phosphate backbone of RNA and the PIL cation framework were the major driving forces for mRNA extraction. The optimized PIL-based SPME method purified a high quantity of mRNA from crude yeast cell lysate compared to a phenol/chloroform extraction method. The reusability and robustness of PIL-based SPME for RNA analysis represents a significant advantage over conventional silica-based solid-phase RNA extraction kits. The selectivity of the SPME method toward mRNA was enhanced by functionalizing the PA sorbent with oligo dT20 using carbodiimide-based amide linker chemistry. The oligo dT20-modified PA sorbent coating demonstrated superior extraction performance than the native PA sorbent coating with quantification cycle (Cq) values 33.74 ± 0.24 and 39, respectively. The modified PA sorbent extracted sufficient mRNA from total RNA at concentrations as low as 5 ng μL-1 in aqueous solutions without the use of organic solvents and time-consuming multiple centrifugation steps that are required in traditional RNA extraction methods.

Application of headspace solid‐phase microextraction followed by gas chromatography coupled with mass spectrometry to determine esters of carboxylic acids and other volatile compounds inDermestes maculatusandDermestes aterlipids

A constant problem in veterinary medicine, human healthcare, agriculture, forestry and horticulture is the large number of pests, and the lack of effective methods to combat them which cause no harm to the rest of the environment. It is recommended and desired to reduce the use of chemicals and increase the use of agents based on knowledge acquired in the fields of biology, chemistry and agrochemicals. To learn the defense mechanisms of insects we should consider not only the site of their physiological ability to protect against external factors (cuticle), but also the possibility of chemical protection, formed by all compounds on the surface and in the body of insects. In this study, a procedure was developed to determine the esters of carboxylic acids in insect lipids. Headspace solid-phase microextraction was followed by gas chromatography coupled with gas spectrometry. First, the best conditions were selected for the analysis to obtain the best chromatographic separation. An RTx-5 column was used for this purpose. Polydimethylsiloxane/divinylbenzene (PDMS/DVB) and polyacrylate fibers were used to isolate acid esters. PDMS/DVB fiber achieved the best conditions for the extraction; the extraction time was 50 min, the extraction temperature was 105°C and the desorption time was 10 min at 230°C. These solid-phase microextraction conditions were used to analyze volatile compounds extracted from insects belonging to the Dermestidae family.

Determination of Trans-resveratrol in Wines, Spirits, and Grape Juices Using Solid-Phase Micro Extraction Coupled to Liquid Chromatography with UV Diode-Array Detection

Solid phase microextraction (polyacrylate fiber), coupled to liquid chromatography with UV diode-array detection, has been optimized for the determination of trans-resveratrol in wines, spirits, and grape juices. The main aspects influencing fiber adsorption (fiber coating, extraction time, ethanol content, salt addition) and desorption (desorption and injection time, desorption solvent mixture composition, carryover) of the analyte have been investigated. The method permitted a fast and simple determination of free trans-resveratrol in commercial samples. It was found in all the analyzed samples at concentration levels ranging from 0.007 to 4.486 μg mL−1. Total trans-resveratrol concentrations were also evaluated after enzymatic deconjugation of piceid.

Solvent-free method for the determination of lignin-derived phenols in sediments.

A solvent-free method that uses headspace solid-phase microextraction and gas chromatography with flame ionization detection is proposed for the determination of lignin-derived phenols in sediments. The extraction and derivatization conditions for the simultaneous analysis of acetosyringone, acetovanillone, syringaldehyde, vanillin, ferulic acid, syringic acid, vanillic acid, p-hydroxybenzoic acid, and p-coumaric acid were optimized using a central composite design. After optimization, the best results were obtained with the following conditions: exposure of the polyacrylate fiber to the headspace with 60μL of N,O-bis(trimethylsilyl)trifluoroacetamide as a derivatizing agent for 15min and then extraction in the headspace of 100mg of sediment (previously spiked with lignin-derived phenols) for 35min. The accuracy of the method was estimated based on recovery tests at two concentration levels and by comparison with a high-performance liquid chromatography method reported in the literature. Based on the t-test with a confidence level of 95%, no statistical differences were observed. The detection and quantification limits for the target compounds varied according to their characteristics: values at the microgram per gram level for nonacid compounds and milligram per gram level for phenolic acids, due to the lower volatility of the derivatives.

Determination of flavor compounds in foxtail millet wine by gas chromatography-mass spectrometry coupled with headspace solid phase microextraction

To comprehensively understand flavor compounds and aroma characteristics of foxtail millet wine, extraction conditions were optimized with 85 μm polyacrylate (PA), 100 μm polydimethylsiloxane (PDMS), 75 μm carboxen (CAR)/PDMS and 50/30 μm divinylbenzene (DVB)/CAR/PDMS fibers. The flavor compounds in foxtail millet wine were investigated by gas chromatography-mass spectrometry (GC-MS) coupled with headspace solid phase microextraction (HS-SPME), and the odor characteristics and intensity were analyzed by odor active values (OAVs). The samples of 8 mL were placed in headspace vials with 1.5 g NaCl, then the headspace vials were heated at 60℃ for 40 min. Using HS-SPME with different fibers, a total of 55 flavor compounds were identified from the samples, including alcohols, esters, benzene derivatives, hydrocarbons, acids, aldehydes, ketones, terpenes, phenols and heterocycle compounds. The main flavor compounds were alcohols compounds. According to their OAVs, phenylethyl alcohol, styrene, 1-methyl-naphthalene, 2-methyl-naphthalene, benzaldehyde, benzeneacetaldehyde and 2-methoxy-phenol were established to be odor-active compounds. Phenylethyl alcohol and benzeneacetaldehyde were the most prominent odor-active compounds. PA and PDMS fibers had good extraction effect for polar and nonpolar compounds, respectively. CAR/PDMS and DVB/CAR/PDMS provided a similar compounds profile for moderate polar compounds. This research comprehensively determined flavor compounds of foxtail millet wine, and provided theoretical basis for product development and quality control.

Qualitative methods for VOC detection in condensed hookah tobacco and steam stone smoke

This work offers a preliminary investigation of the compounds in smoke from hookah tobacco and tobacco-free steam stone products. A preconcentration extraction method involving headspace solid phase microextraction (SPME) and gas chromatography mass spectrometry (GC–MS) was developed for the qualitative analysis of condensed hookah smoke (CHS). A simulated hookah apparatus was constructed to smoke hookah tobacco or steam stones with coconut, wood, or electronic charcoals used as the heat source. The vapor was collected by condensing the mainstream smoke as it passed through a 15mL vacuum cold trap vial inside an acetonitrile/dry ice cold bath at −40°C. Multiple SPME fibers (a 50/30μm DVB/CAR®/PDMS fiber, a 65μm PDMS/DVB fiber, an 85μm CAR®/PDMS fiber, a 100μm PDMS fiber, and an 85μm Polyacrylate fiber) were used to qualitatively screen compounds present in the highly complex hookah smoke condensate. An in-house reference composed of 3R4F reference cigarettes was used to estimate SPME extraction and desorption times (5min and 1min, respectively). Chromatograms indicated that the hookah tobacco condensate contained more compounds than the steam stone condensate and a preliminary attempt was made to assign peaks to their source compounds using mass spectral information. Principal component analysis (PCA) of peak signal intensities suggested that the 65μm PDMS/DVB, 85μm CAR®/PDMS, and 85μm Polyacrylate fibers extracted tobacco and steam stone volatile organic compounds (VOCs) most consistently. The complexity of hookah tobacco and steam stone smoke limits our ability to quantify the compounds at this time, however identification and quantitation will be the focus of future work.

Antibacterial properties and reduction of MRSA biofilm with a dressing combining polyabsorbent fibres and a silver matrix.

This study was designed to evaluate the antibacterial activity of a wound dressing which combines polyacrylate fibres and a silver lipido-colloid matrix (UrgoClean Ag, silver polyabsorbent dressing), against biofilm of methicillin-resistant Staphylococcus aureus (MRSA). Samples of silver polyabsorbent dressing and the neutral form of this dressing (UrgoClean) were applied to biofilms of MRSA formed on a collagen I-coated surface, cultured for 24 hours. Different exposure times were tested (1, 2, 4 and 7 days) without dressing change. The biofilm reduction was quantified by using culture methods and by confocal laser scanning microscopy experiments. The application of the silver polyabsorbent dressing resulted in a significant decrease of the biofilm population by a log reduction of 4.6, after 24 hours of exposure. Moreover, the antibiofilm activity was maintained for 7 days with reduction values up to 4 log (reduction of biofilm superior to 99.99%). The application of the neutral dressing also induced a significant reduction of the concentration of sessile cells after 1 day (about 0.90 log). The results obtained with this neutral form of the dressing showed that the polyacrylate fibres were able to exert a mechanical disruption of the biofilm architecture. These in vitro experiments demonstrated that silver polyabsorbent dressing was able to strongly reduce the biofilm of MRSA. The antibiofilm mechanism of this dressing can be explained by a dual action of the polyabsorbent fibres (based on ammonium polyacrylate polymer around an acrylic core) which induced a mechanical disruption of the biofilm matrix and/or a sequestration of sessile cells, and the diffusion of silver ions which produced bactericidal activity. This study was supported by Laboratoires Urgo (Dijon). P. Janod is an employee of Laboratoires Urgo. The company had no influence on the experimental design and the interpretation of the results.