Carboxen-polydimethylsiloxane Fiber Research Articles

Enhancement of Benzene Emissions in Special Combinations of Electronic Nicotine Delivery System Liquid Mixtures.

Electronic nicotine delivery systems (ENDS) are battery-powered devices introduced to the market as safer alternatives to combustible cigarettes. Upon heating the electronic liquid (e-liquid), aerosols are released, including several toxicants, such as volatile organic compounds (VOCs). Benzene has been given great attention as a major component of the VOCs group as it increases cancer risk upon inhalation. In this study, several basic e-liquids were tested for benzene emissions. The Aerosol Lab Vaping Instrument was used to generate aerosols from ENDS composed of different e-liquid combinations: vegetable glycerin (VG), propylene glycol (PG), nicotine (nic), and benzoic acid (BA). The tested mixtures included PG, PG + nic + BA, VG, VG + nic + BA, 30/70 PG/VG, and 30/70 PG/VG + nic + BA. A carboxen polydimethylsiloxane fiber for a solid-phase microextraction was placed in a gas cell to trap benzene emitted from a Sub-Ohm Minibox C device. Benzene was adsorbed on the fiber during the puffing process and for an extra 15 min until it reached equilibrium, and then it was determined using gas chromatography-mass spectrometry. Benzene was quantified in VG but not in PG or the 30/70 PG/VG mixtures. However, benzene concentration increased in all tested mixtures upon the addition of nicotine benzoate salt. Interestingly, benzene was emitted at the highest concentration when BA was added to PG. However, lower concentrations were found in the 30/70 PG/VG and VG mixtures with BA. Both VG and BA are sources of benzene. Enhanced emissions, however, are mostly noticeable when BA is mixed with PG and not VG.

Rapid Analysis of 27 Volatile Sulfur Compounds in Wine by Headspace Solid-Phase Microextraction Gas Chromatography Tandem Mass Spectrometry

Volatile sulfur-containing compounds (VSCs) play an important role in wine aroma conferring at high concentrations unpleasant odors but also participating positively at low concentration. A large number of VSCs are formed at different stages of winemaking and storage. To monitor this phenomenon, a HS-SPME-GC-MS/MS method has been developed. The method is proposed in order to quantify 27 different sulfur-containing compounds. SPME extraction was performed using a carboxen-polydimethylsiloxane (CAR-PDMS) fiber, which resulted the most effective fiber coating. Time and temperature extraction conditions were optimized using response surface methodology. The selectivity and sensitivity of the method were considerably increased using triple-quadrupole in multiple reaction monitoring (MRM) mode. The number of VSCs analyzed in a single run was higher than in any other method previously reported using single-quadrupole MS or other detectors. The overall process was successfully applied to identify and quantify sulfur compounds both in white and red wines.

Simultaneous determination of volatile organic compounds with a wide range of polarities in urine by headspace solid-phase microextraction coupled to gas chromatography/mass spectrometry.

Volatile organic compounds (VOCs) are ubiquitous environmental pollutants that have a high vapor pressure at room temperature. Some VOCs have been classified as carcinogenic to humans by the International Agency for Research on Cancer (IARC), because they can bind to DNA and cause cell mutations. Therefore, monitoring of VOCs in human urine is very important to evaluate the correlation between exposure to VOCs and human disease. We have developed an improved analytical method for the simultaneous determination of VOCs with a wide range of polarities in human urine samples by headspace solid-phase microextraction (HS-SPME) coupled to gas chromatography/mass spectrometry (GC/MS). In the improved method, a bi-polar carboxen-polydimethylsiloxane (CAR/PDMS) fiber was used for the optimized extraction of 15 VOCs with a wide range of polarities, including benzene, toluene, ethylbenzene, xylenes (BTEX), alkylbenzenes, cresols, and naphthalene, in human urine samples. Extracted VOCs from the human urine were effectively separated by GC using a mid-polarity column (DB-35, 35% phenylmethylpolysiloxane) and monitored by MS using extracted ion monitoring (EIM) mode. Under the optimized method, the linearity of the calibration curves was greater than 0.993. The limits of detection (LODs) at a signal-to-noise (S/N) ratio of 3 were 0.3-0.6ng/mL. The coefficients of variation were in the range of 0.1-9.7% for within-day variation and 0.2-14.2% for day-to-day variation. The method was shown to be rapid and simple for the simultaneous determination of VOCs with a wide range of polarities in human urine and it could be applied to monitoring and to biomedical investigations to check exposure to VOCs. Copyright © 2017 John Wiley & Sons, Ltd.

Volatile Composition of Sweet Passion Fruit (Passiflora alata Curtis)

Passiflora alata Curtis (sweet passion fruit) is a native species grown in South America, especially in Brazil. In addition to being aromatic, its pulp is sweeter and less acidic compared to traditional commercial passion fruits, and this makes it highly appreciated for fresh consumption. Its aroma is also very distinct from other passion fruit species but it has not been characterized so far. In the present study, for the first time, the volatile composition of sweet passion fruit was investigated. Two genotypes (BGM004 and BGM163) were evaluated and two SPME fibers were tested. Forty-five volatile compounds were properly identified and semiquantified. The carboxen-polydimethylsiloxane (CAR/PDMS) fiber presented better performance regarding both number and concentration of compounds. Esters and terpenes were the main volatile classes. Methyl butanoate, methyl (E)-2-butenoate, ethyl butanoate, ethyl (E)-2-butenoate, methyl 2-hexenoate, and ethyl-2-hexenoate were among major compounds. As complementary results, sugar content, titratable acidity, pH, and total soluble solids were evaluated.

Use of Headspace Solid-phase Microextraction in Rose (Rosa damescena Mill) Products for Volatile Compounds

Headspace-solid phase microextraction (HS-SPME) combined with gas chromatography-mass spectrometry (GC-MS) was applied to the analysis of volatiles of rose products (rose, conrete, rose absolute, and rose oil). The SPME headspace volatiles were collected using a 75 µM Carboxen-polydimethylsiloxane fiber (CAR/PDMS) as suitable for volatile compounds. Forty six compounds were identified by GC-MS, representing 94.30 - 98.61 % of the total amount. Gas chromatography-Mass spectrometric analysis revealed rose concrete and absolute to be rich in phenylethyl alcohol (75.79 and 81.32 %, respectively), and rose oil to be rich in β-citronellol (34.38 %) and geraniol (13.99 %). Higher levels of terpenoid compounds were found in rose concrete and oil in contrast to rose absolute.

Matrix effects of milk, dairy factory wastewater and soil water on the determination of disinfection by‐products and para‐cresol using solid‐phase microextraction

Assessing pollutant concentrations can be hampered by the complex matrices found in the dairy supply/processing chain. Matrix effects were examined using solid‐phase microextraction (SPME) used to sample haloacetic acid methyl esters (HAAMe) and para‐cresol. In general, HAAMe were more difficult to detect with a polydimethylsiloxane fibre than with carboxen–polydimethylsiloxane fibre. Headspace sampling generally provided better detection of HAAMe than direct immersion with the reverse true for para‐cresol. For para‐cresol, equivalent ratios up to 18.8 were detected. Other compounds detected included sulphides, VOC's, phenols and indoles. For milk samples, most compounds collected by SPME were found using direct immersion.

Development of a Headspace-Solid Phase Microextraction-Gas Chromatography/Mass Spectrometry (HS-SPME-GC/MS) Method for the Determination of Benzene in Soft Drinks

A method based on headspace-solid phase microextraction and gas chromatography with mass spectrometry has been developed and validated for the determination of benzene in soft drinks. The extraction step was optimized using a rotatable central composite design including the following experimental variables: extraction temperature, extraction time, sample weight, and salt concentration. The optimized procedure, which was carried out at 30 °C during 30 min by using a 75 μm carboxen-polydimethylsiloxane fiber, showed good linearity within the concentration range 0–25 μg kg−1 (r 2 > 0.999), mean recoveries from 97.5 to 103.1 %, and coefficients of variation from 1.5 to 13.4 % for repeatability and from 1.5 to 15.7 % for within-laboratory reproducibility. Limits of detection and quantification were calculated at 0.02 and 0.08 μg kg−1, respectively. The method was applied to determine the concentrations of benzene in 77 samples of beverages from the Brazilian market. Levels from <0.08 to 10.84 μg kg−1 were obtained, which are comparable to those verified in other countries. Most of the samples (72.2 %) contained benzene up to 1 μg kg−1.

Chemotherapy control by breath profile with application of SPME‐GC/MS method

Chemotherapy used as a treatment against lung cancer has influence on metabolic processes occurring in healthy cells. The changes of biochemical pathways proceeded inside cells might be observed in expired air. In the experiment, breath analysis was carried out before and after anticancer therapy. Expired air samples were collected from 22 patients with a biopsy confirmed lung cancer. Volatile organic compounds present in breath were analyzed by gas chromatography/mass spectrometry. For enrichment of analytes solid-phase microextraction technique was applied. Eight fibers covered by different sorbents were tested. Carboxen-polydimethylsiloxane fiber revealed the highest extraction efficiency in relation to analytes in breath. The data showed that cytostatic drugs increase the concentration of acetone and isoprene in the breath collected after chemotherapy. Volatile metabolites of administrated drugs were not identified in expired air.

Potential Applications of HS-SPME/GC in Oxidized Vegetable Oils

Headspace solid phase microextraction chromatography (HS-SPME/GC) was evaluated as a tool in determining the rate of oxidation in oxidized soybean oil samples by measuring the production of hexanal as a secondary major volatile breakdown product of linoleic acid. Samples of the headspace taken from sealed 20 mL vials, incubated 30 min at 50 °C followed by 5 min adsorption, were injected into a gas chromatograph with 2 min thermal desorption. In applying SPME, different analytical conditions were evaluated. The linearity of response of the volatiles for the HS-SPME/GC procedure using a carboxen-polydimethylsiloxane fiber was determined from 3 g of mineral oil spiked with a hexanal standard solution at different levels. Using the optimized extraction conditions, an R value close to unity (R = 0.999) was found, and the repeatability (n = 11) was 6.31%. The results indicated that hexanal is linearly related to peroxide value (PV) only intermediate PV ranges (10-18 meq/kg). The study also showed that HS-SPME/GC procedure was a simple and reproducible method for the analysis of hexanal in the HS of commercial soybean oil samples, and is useful as a quality control and research tool for the evaluation of flavor quality and shelf life of vegetable oils.

Comparison of two headspace sampling techniques for the analysis of off-flavour volatiles from oat based products.

Two different headspace sampling techniques were compared for analysis of aroma volatiles from freshly produced and aged plain oatcakes. Solid phase microextraction (SPME) using a Carboxen-Polydimethylsiloxane (PDMS) fibre and entrainment on Tenax TA within an adsorbent tube were used for collection of volatiles. The effects of variation in the sampling method were also considered using SPME. The data obtained using both techniques were processed by multivariate statistical analysis (PCA). Both techniques showed similar capacities to discriminate between the samples at different ages. Discrimination between fresh and rancid samples could be made on the basis of changes in the relative abundances of 14-15 of the constituents in the volatile profiles. A significant effect on the detection level of volatile compounds was observed when samples were crushed and analysed by SPME-GC-MS, in comparison to undisturbed product. The applicability and cost effectiveness of both methods were considered.

Determination of volatile organic compounds in recycled polyethylene terephthalate and high-density polyethylene by headspace solid phase microextraction gas chromatography mass spectrometry to evaluate the efficiency of recycling processes

A method for the determination of volatile organic compounds (VOCs) in recycled polyethylene terephthalate and high-density polyethylene using headspace sampling by solid-phase microextraction and gas chromatography coupled to mass spectrometry detection is presented. This method was used to evaluate the efficiency of cleaning processes for VOC removal from recycled PET. In addition, the method was also employed to evaluate the level of VOC contamination in multilayer packaging material containing recycled HDPE material. The optimisation of the extraction procedure for volatile compounds was performed and the best extraction conditions were found using a 75 μm carboxen-polydimethylsiloxane (CAR-PDMS) fibre for 20 min at 60 °C. The validation parameters for the established method were linear range, linearity, sensitivity, precision (repeatability), accuracy (recovery) and detection and quantification limits. The results indicated that the method could easily be used in quality control for the production of recycled PET and HDPE.

Volatile Compounds in Honey Produced in the Central Valley of Ñuble Province, Chile

Headspace solid-phase microextraction (SPME) with an 85 µm Carboxen polydimethylsiloxane (CAR/PDMS) fiber was used to extract volatile compounds, and a gas chromatograph equipped with a mass spectometry detector (GCMS) was used to identify the volatile compounds in honeys. Thirty-four different volatile compounds from the headspace of honey produced in the central valley of Nuble Province, Chile, were extracted with fiber coating CAR/PDMS. The identified compounds were: 10 alcohols, 9 acids, 6 ketones, 3 aldehydes, 2 furans, 2 terpenes and 2 lactones. Only four of the volatile compounds had never been reported before as honey compounds; these being: 1,3-propanodiol, 2-methyl butanoic acid, 3,4-dimethyl-3-hexen-2-one, and 6-methyl-5-octen-2-one. These four compounds were found in three of the 10 analyzed samples. The compounds found in the highest percentage of area were ethanol, acetic acid, 1-hydroxy-2-propane, 3-hydroxy-2-butane, and furfural. However, the analyzed samples did not present a distinctive profile.

Determination of cosmetic ingredients causing extrusion‐coated and adhesive joint multilayer packaging delamination

AbstractIn order to study the effect of several compounds on packaging stability, different cosmetic ingredients at two concentration levels were added to a NeoPCL® (Acofarma, Terrassa, Spain) water emulsion, and the preparations packed in sachets and stored at 40°C during 3 months. After that, the packaging was subjected to a T‐peel test and headspace solid‐phase microextraction gas chromatography mass spectrometry (HS‐SPME‐GC‐MS) analysis. The HS‐SPME‐GC‐MS analyses were performed using a 75 μm carboxen polydimethylsiloxane fibre to check for the presence of the studied analytes in the inner layers. The study revealed that the presence of a phenyl and a hydroxyl group in the compound structure lead to an important loss of adhesion between packaging layers joined by an adhesive. The interaction between the cosmetic ingredient and the adhesive was proposed as the main cause of the loss of adhesion. However, extrusion‐coating packaging was more susceptible to delamination, particularly with the volatile compounds. Copyright © 2009 John Wiley &amp; Sons, Ltd.

Solid‐phase microextraction for determining twelve orange flavour compounds in a model beverage emulsion

Solid-phase microextraction (SPME) coupled to gas chromatography has been applied for the headspace analysis (HS) of 12 target flavour compounds in a model orange beverage emulsion. The main volatile flavour compounds studied were: acetaldehyde, ethyl acetate, alpha-pinene, ethyl butyrate, beta-pinene, myrcene, limonene, gamma-terpinene, octanal, decanal, linalool and citral (neral plus geranial). After screening the fibre type, the effect of other HS-SPME variables such as adsorption temperature (25-55 degrees C), extraction time (10-40 min), sample concentration (1-100% w/w), sample amount (5-10 g) and salt amount (0-30% w/w) were determined using a two-level fractional factorial design (2(5-2)) that was expanded further to a central composite design. It was found that an extraction process using a carboxen-polydimethylsiloxane fibre coating at 15 masculineC for 50 min with 5 g of diluted emulsion 1% (w/w) and 30% (w/w) of sodium chloride under stirring mode resulted in the highest HS extraction efficiency. For all volatile flavour compounds, the linearity values were accurate in the concentration ranges studied (r(2) > 0.97). Average recoveries that ranged from 90.3 to 124.8% showed a good accuracy for the optimised method. The relative standard deviation for six replicates of all volatile flavour compounds was found to be less than 15%. For all volatile flavour compounds, the limit of detection ranged from 0.20 to 1.69 mg/L.

Solid-phase microextraction method for the determination of volatile compounds associated to oxidation of fish muscle

A procedure for the determination of volatile compounds derived from lipid oxidation of fish muscle samples is presented. Analytes are concentrated on a solid-phase microextraction fiber employed in the headspace mode (HS-SPME), and selectively determined using gas chromatography in combination with mass spectrometry (GC–MS). The influence of several parameters on the efficiency of microextraction such as type of fiber, volume of sample, time, temperature, salting-out effect and stirring was systematically investigated. A saline extraction of fish muscle followed by incubation on a Carboxen-polydimethylsiloxane fiber during 30 min at 60 °C gave the most effective and accurate extraction of the analytes. Quantification of them was performed by MS in the selected ion monitoring mode and by the internal standard method. Satisfactory linearity, repeatability and quantification limits were achieved under these conditions. The method was applied to the determination of the volatile compounds associated to oxidation of Atlantic horse mackerel ( Trachurus trachurus) minced muscle and excellent correlations were obtained with chemical indexes for monitoring lipid oxidation as peroxide value and thiobarbituric acid reactive substances. This combined technique is fast, simple, sensitive, inexpensive and useful to monitor target compounds associated to fish rancidity as 1-penten-3-ol, 2,3-pentanedione or 1-octen-3-ol.

Application of Headspace Solid-Phase Microextraction for Determination of Chloro-Organic Compounds in Sewage Samples

ABSTRACTSolid phase microextraction (SPME) has been optimized and applied to the determination of the volatile halogenated compounds (VHCs) and semi-volatile halogenated compounds (SVHCs). Three types of SPME fiber coated with different stationary phases (PDMS—100 μm, CAR/PDMS—75 μm, PDMS/DVB—65 μm) were used to examine their extraction efficiencies for the compounds tested. Experimental parameters such as the selection of SPME coatings, extraction time, and addition of salts were studied. The carboxen-polydimethylsiloxane (CAR/PDMS) fiber appears to be the most suitable for the determination of VHCs. Analytical parameters such as linearity, limit of detection, and precision were also evaluated. Application of ECD detector for the determination of VHCs and SVHCs allows their determination on the low concentration level, ranging from 0.005 to 0.8 μg/L−1. The HS-SPME-GC/ECD procedure gave good analytical precision expressed as relative standard deviation (RSD) (ranged from 5.08% to 8.07%) for a concentration level of 5 μg/L−1 and good linearity (r2 >0.98) in a wide calibration range. The applied HS-SPME-GC/ECD method was found to be a quick and effective technique for the determination of microtrace amounts of volatile and semi-volatile halogenated compounds in samples containing high amounts of various organic compounds.

Compound-specific carbon isotope analysis of volatile organic compounds in water using solid-phase microextraction

The compound-specific isotope analysis technique in conjunction with solid-phase microextraction using a carboxen–polydimethylsiloxane fiber was tested and implemented for isotopes analyses of organic compounds aiming for environmental application in contaminated groundwater. δ 13C values of several chlorinated methanes and ethenes, toluene and chlorobenzene were determined using a gas chromatograph coupled to an isotope ratio mass spectrometer through a combustion interface. Direct and headspace solid-phase microextraction (D-SPME, HS-SPME) methods were tested in order to determine the optimum conditions to obtain reproducible δ 13C values at very low concentration (μg/L range) and, to elucidate the carbon isotopic effects associated with the competitive extraction. For D-SPME, higher accuracy and precision of δ 13C results were obtained with no salted aqueous standards. Despite that the δ 13C of those compounds analyzed with both methods showed similar precision (<0.5‰) and accuracy, the highest sensitivity was reached with HS-SPME. Furthermore, the δ 13C values of cis-1,2-dichloroethylene, chorinated methanes and aromatic compounds obtained using HS-SPME showed measurable deviations with respect to the isotopic composition of pure phase compounds, however, these deviations are constant according to the analytical uncertainties, indicating that they are not affected by competitive extraction, and they could be corrected using standard correction technique based on internal calibrated standards.

Quantitative determination of wine highly volatile sulfur compounds by using automated headspace solid-phase microextraction and gas chromatography-pulsed flame photometric detection: Critical study and optimization of a new procedure

The quantitative determination of wine volatile sulfur compounds by automated headspace solid-phase microextraction (HS-SPME) with a carboxen-polydimethylsiloxane (CAR-PDMS) fiber and subsequent gas chromatography-pulsed flame photometric detection (GC-PFPD) has been evaluated. The direct extraction of the sulfur compounds in 5ml of wine has been found to suffer from matrix effects and short linear ranges, problems which could not be solved by the use of different internal standards or by multiple headspace SPME. These problems were attributed to saturation of the fiber and to competitive effects between analytes, internal standards and other wine volatiles. Another problem was the oxidation of analytes during the procedure. The reduction in sample volume by a factor 50 (0.1ml diluted with water or brine) brought about a reduction in the amount of sulfur compounds taken in the fiber by a factor just 3.3. Consequently, a new procedure has been proposed. In a sealed vial containing 4.9ml of saturated NaCl brine, the air is thoroughly displaced with nitrogen, and the wine (0.1ml) and the internal standards (0.02ml) are further introduced with a syringe through the vial septum. This sample is extracted at 35°C for 20min. This procedure makes a satisfactory determination possible of hydrogen sulfide, methanethiol, ethanethiol, dimethyl sulfide, diethyl sulfide and dimethyl disulfide. The linear dynamic ranges cover the normal ranges of occurrence of these analytes in wine with typical r2 between 0.9823 and 0.9980. Reproducibility in real samples ranges from 10 to 20% and repeatability is better than 10% in most cases. The method accuracy is satisfactory, with errors below 20% for hydrogen sulfide and mostly below 10% for the other compounds. The proposed method has been applied to the analysis of 34 Spanish wines.

Fibre selection based on an overall analytical feature comparison for the solid-phase microextraction of trihalomethanes from drinking water

This paper describes the optimization of solid-phase microextraction (SPME) conditions for three different fibres (Carboxen-polydimethylsiloxane (CAR-PDMS), divinylbenzene-Carboxen-polydimethylsiloxane (DVB-CAR-PDMS) and polydimethylsiloxane-divinylbenzene (PDMS-DVB)) used to determine trihalomethanes (THMs) in water by headspace solid-phase microextraction and gas chromatography (HS-SPME-GC). The influence of temperature and salting-out effect was examined using a central composite design for each fibre. Extraction time was studied separately at the optimum values found for temperature and sodium chloride concentration (40 °C and 0.36 g mL −1). The HS-SPME-GC-MS method for each fibre was characterised in terms of linearity, detection (LOD) and quantification (LOQ) limits and repeatability. The fibre PDMS-DVB was selected as it provided a broader linear range, better repeatability and lower detection and quantification limits than the others, particularly CAR-PDMS fibre. The accuracy of the proposed method using the PDMS-DVB fibre was checked by a recovery study in both ultrapure and tap water. A blank analysis study showed the absence of memory effects for this fibre. The reproducibility (expressed as a percentage of relative standard deviation) was 6–11% and the detection limits were between 0.078 and 0.52 μg L −1 for bromoform and chloroform, respectively. Finally, the method was applied to determine THM concentration in two drinking water samples.

Characterization of volatile organic compounds and odors by in-vivo sampling of beef cattle rumen gas, by solid-phase microextraction, and gas chromatography–mass spectrometry–olfactometry

Volatile organic compounds (VOCs) and odors in cattle rumen gas have been characterized by in-vivo headspace sampling by solid-phase microextraction (SPME) and analysis by gas chromatography-mass spectrometry-olfactometry (GC-MS-O). A novel device enabling headspace SPME (HS-SPME) sampling through a cannula was designed, refined, and used to collect rumen gas samples from steers. A Carboxen-polydimethylsiloxane (PDMS) fiber (85 microm) was used for SPME sampling. Fifty VOCs from ten chemical groups were identified in the rumen headspace. The VOCs identified had a wide range of molecular weight (MW) (34 to 184), boiling point (-63.3 to 292 degrees C), vapor pressure (1.05x10(-5) to 1.17x10(2) Pa), and water solubility (0.66 to 1x10(6) mg L-1). Twenty-two of the compounds have a published odor detection thresholds (ODT) of less than 1 ppm. More than half of the compounds identified are reactive and have an estimated atmospheric lifetime of <24 h. The amounts of VFAs, sulfide compounds, phenolic compounds, and skatole, and the odor intensity of VFAs and sulfide compounds in the rumen gas were all higher after feeding than before feeding. These results indicate that rumen gases can be an important potential source of aerial emissions of reactive VOCs and odor. In-vivo sampling by SPME then GC-MS-O analysis can be a useful tool for qualitative characterization of rumen gases, digestion, and its relationship to odor and VOC formation.