Selective extraction of CO2 from simulated flue gas using polymeric ionic liquid sorbent coatings in solid-phase microextraction gas chromatography

The CO₂ selectivity of two polymeric task-specific ionic liquid sorbent coatings, poly(1-vinyl-3-hexylimidazolium) bis[(trifluoromethyl)sulfonyl]imide [poly(VHIM-NTf₂)] and poly(1-vinyl-3-hexylimidazolium) taurate [poly(VHIM-taurate)], was examined using solid-phase microextraction (SPME) for the determination of CO₂ in simulated flue gas. For comparison purposes, a commercial SPME fiber, Carboxen™-PDMS, was also studied. A study into the effect of humidity revealed that the poly(VHIM-taurate) fiber exhibited enhanced resistance to water, presumably due to the unique mechanism of CO₂ capture. The effect of temperature on the performance of the PIL-based and Carboxen fibers was examined by generating calibration curves under various temperatures. The sensitivity, linearity, and linear range of the three fibers were evaluated. The extraction of CH₄ and N₂ was performed and the selectivities of the PIL-based and Carboxen fibers were compared. The poly(VHIM-NTf₂) fiber was found to possess superior CO₂/CH₄ and CO₂/N₂ selectivities compared to the Carboxen fiber, despite the smaller film thicknesses of the PIL-based fibers. A scanning electron microscopy study suggests that the amine group of the poly(VHIM-taurate) is capable of selectively reacting with CO₂ but not CH₄ or N₂, resulting in a significant surface morphology change of the sorbent coating.     

Tuning the selectivity of polymeric ionic liquid sorbent coatings for the extraction of polycyclic aromatic hydrocarbons using solid-phase microextraction

A new generation polymeric ionic liquid (PIL), poly(1-4-vinylbenzyl)-3-hexadecylimidazolium bis[(trifluoromethyl)sulfonyl]imide (poly(VBHDIm⁺ NTf₂⁻)), was synthesized and is shown to exhibit impressive selectivity towards the extraction of 12 polycyclic aromatic hydrocarbons (PAHs) from aqueous samples when used as a sorbent coating in direct-immersion solid-phase microextraction (SPME) coupled to gas chromatography (GC). The PIL was imparted with aromatic character to enhance π–π interactions between the analytes and the sorbent coating. For comparison purposes, a PIL with similar structure but lacking the π–π interaction capability, poly(1-vinyl-3-hexadecylimidazolium bis[(trifluoromethyl)sulfonyl]imide) (poly(HDIm⁺ NTf₂⁻)), as well as a commercial polydimethylsiloxane (PDMS) sorbent coating were evaluated and exhibited much lower extraction efficiencies. Extraction parameters, including stir rate and extraction time, were studied and optimized. The detection limits of poly(VBHDIm⁺ NTf₂⁻), poly(HDIm⁺ NTf₂⁻), and PDMS coatings varied between 0.003–0.07 μg L⁻¹, 0.02–0.6 μg L⁻¹, and 0.1–6 μg L⁻¹, respectively. The partition coefficients (log K_fs) of eight PAHs to the three studied fiber coatings were estimated using a static SPME approach. This study represents the first report of analyte partition coefficients to any PIL-based material.     

Determination of oxadiazon residues by headspace solid-phase microextraction and gas chromatography-mass spectrometry

A method for the determination of trace amounts of the herbicide oxadiazon was developed using headspace solid-phase microextraction (HS-SPME), gas chromatography-mass spectrometry (GC-MS) and selected ion monitoring. It was applied to determine oxadiazon in ground water, agricultural soil, must, wine and human urine samples. To determine oxadiazon in liquid samples, a response surface methodology generated with a Doehlert design was applied to optimize the HS-SPME conditions using a 100 microm polydimethylsiloxane fibre. For the analysis of soil samples, they were mixed with water and the SPME fibre suspended in the headspace above the slurry. Ground water, human urine and must show linear concentration range of application of 0.5-50 ng ml(-1)' with detection limits < or =0.02 ng ml(-1). HS-SPME-GC-MS analysis yielded good reproducibility (RSD values between 6.5 and 13.5%). The method validation was completed with spiked matrix samples. The developed analytical procedure is solvent free, cost effective and fast.     

Determination of additives in cosmetics by supercritical fluid extraction on-line headspace solid-phase microextraction combined with gas chromatography-mass spectrometry

A new hyphenated technique couples supercritical fluid extraction in situ derivatization and on-line headspace solid-phase microextraction to gas chromatography-mass spectrometry (SFE in situ derivatization on-line HS-SPME-GC-MS) for the determination of paraben preservatives and polyphenolic antioxidants in cosmetics. The preservatives and antioxidants were extracted from the cosmetic matrices with supercritical carbon dioxide at a pressure of 13,840 kPa. The supercritical fluid extraction was performed at 55 °C for 10 min of static extraction then 15 min of dynamic extraction. The extractant subsequently was derivatized in situ with the silylation reagent N,O-bis(trimethylsilyl)trifluoroacetamide with 0.1% trimethylchlorosilane. The product was then adsorbed on a polyacrylate solid-phase microextraction (SPME) fiber in the headspace. Sea sand was used as a dispersive material in the SFE step. The analytical linear ranges for the preservatives and antioxidants were found to be from 10 to 1000 ng g⁻¹ with RSD values below 7.8%. The detection limits ranged from 0.5 to 8.3 ng g⁻¹. These results are better than those obtained by using only SPME or SFE for trace preservatives and antioxidants analysis in cosmetic matrices. The new method was successfully utilized to determine the amounts of preservatives and antioxidants in real cosmetics without the need for tedious pretreatments.     

Determination of nonylphenol and octylphenol in paper by microwave-assisted extraction coupled to headspace solid-phase microextraction and gas chromatography-mass spectrometry

A novel and simple method for the determination of active endocrine disrupter compounds (octylphenol OP, and nonylphenol NP) in paper using microwave-assisted extraction (MAE) and headspace solid-phase microextraction, coupled with gas chromatography-mass spectrometry has been developed. Parameters affecting the efficiency in the MAE process such as exposure time and extraction solvent were studied in order to determine operating conditions. The optimised method was linear over the range studied (1.25-125 microg kg(-1) for OP and 9.50-950 microg kg(-1) for NP) and showed good level of precision, with a RSD lower than 10% and detection limits at 0.10 and 4.56 microg kg(-1) for OP and NP, respectively. The results obtained from six different types of paper revealed the presence of the target compounds in all samples analysed, at levels ranging between 3 and 211 microg kg(-1).     

Fast determination of paeonol in plasma by headspace solid-phase microextraction followed by gas chromatography-mass spectrometry

Paeonol is the active component in the traditional Chinese medicines (TCMs), such as Cynanchum paniculatum, which has been used to treat many diseases, such as eczema. In this work, a simple, rapid and sensitive method was developed for the determination of paeonol in rabbit plasma, which was based on headspace solid-phase microextraction (HS-SPME) followed by gas chromatography-mass spectrometry (GC-MS). The extraction parameters of fiber coating, sample temperature, extraction time, stirring rate and ion strength were systemically optimized; the method linearity, detection limit and precision were also investigated. It was shown that the proposed method provided a good linearity (0.02-20 μg mL⁻¹, R² > 0.990), low detection limit (2.0 ng mL⁻¹) and good precision (R.S.D. value less than 8%). Finally, GC/MS following HS-SPME was applied to fast determination of paeonol in rabbit plasma at different time point after oral demonstration of Cynanchum paniculatum essential oil. The experimental results suggest that the proposed method provided an alternative and novel approach to the pharmacokinetics study of paeonol in the TCMs.     

Determination of volatile oak compounds in wine by headspace solid-phase microextraction and gas chromatography-mass spectrometry

A headspace solid-phase microextraction (HS-SPME) and gas chromatography (GC) coupled to mass spectrometry (MS) method was developed to identify and quantify 14 volatile oak compounds in aged red wines. The most important HS-SPME variables were optimised by experimental design technique in order to improved the extraction process. The selected conditions were: 10 mL of sample in 20 mL sealed vials with addition of 30% of sodium chloride (saturated solution), divinylbenzene-carboxen-polydimethylsiloxane (DVB-CAR-PDMS) fibre, 10 min of pre-incubation time, 70 degrees C of temperature and 60 min of extraction time without agitation. The features of the method were established for the studied compounds in terms of linear range, slope and intercept of the calibration graphs, detection and quantification limits and repeatability. For all compounds detection limits were below their threshold levels and repeatability, in terms of relative standard deviation, was good, with values between 3 and 11%. Finally, the method was applied to the analysis of six aged red wines by both internal standard and standard addition calibration methods. The concentrations obtained with both methods were statistically compared.     

Determination of chloroanisole compounds in red wine by headspace solid-phase microextraction and gas chromatography-mass spectrometry

The objectives of this study, were the development and validation of an analytical method for the determination of 2,4,6-trichloroanisole (TCA), 2,3,4,6-tetrachloroanisole (TeCA) and pentachloroanisole (PCA) in red wine by headspace solid-phase microextraction and GC-MS as well as the application of the optimized and validated method for the quatification of chloroanisoles in different red wines from Navarra. To carry out this study, the extraction variables have been optimized. The fiber and the experimental design selected permit the determination of low analyte concentrations (ng/L) with good accuracy (<5%). Moreover, an analytical method for the determination of TCA and TeCA in wine by GC-MS has been validated. The results obtained in the validation step, recovery values, detection and quantitative limits, and precision were acceptable for all the analytes in the ranges of concentration studied (<5% and <10% for TCA and TeCA, respectively). This method has been used as an analytical method for the quantification of TCA and TeCA in red wine samples that were selected for this study, yielding good results.     

顶空固相微萃取-气相色谱-质谱联用测定香水中5种合成麝香

建立了香水中5种合成麝香的顶空固相微萃取-气相色谱-质谱联用分析方法。实验选用65 μm的聚二甲基硅氧烷-二乙烯基苯(PDMS-DVB)萃取纤维,在磁力搅拌600 r/min条件下,考察了萃取温度、平衡时间、萃取时间、解吸时间、进样口温度和盐效应6个方面对实验结果的影响。优化后的条件为: 10 mL顶空瓶中加入适量用水稀释过的样品,于60 ℃平衡3 min后,顶空萃取20 min,随即插入气相色谱进样口,于250 ℃解吸3 min进行定性、定量分析。5种合成麝香在0.05～1.00 μg/g范围内线性关系良好,检出限(LOD)为0.6～2.1 ng/g。空白样品在3个浓度加标水平下(0.05, 0.50, 1.00 μg/g)的回收率为82.0%～103.3%,相对标准偏差(RSD)为1.8%～9.4%。本方法简便、准确、快速、灵敏,适用于香水中合成麝香的分析检验工作。     

Determination of water pollutants by direct-immersion solid-phase microextraction using polymeric ionic liquid coatings

The determination of a group of eighteen pollutants in waters, including polycyclic aromatic hydrocarbons and substituted phenols, is conducted in direct-immersion solid-phase microextraction (SPME) using the polymeric ionic liquid (PIL) poly(1-vinyl-3-hexadecylimidazolium) bis[(trifluoromethyl)sulfonyl]imide as a novel coating material. The performance of the PIL fiber coating in the developed IL-SPME-gas chromatography (GC)–mass spectrometry (MS) method is characterized by average relative recoveries of 92.5% for deionized waters and 90.8% for well waters, average precision values (as relative standard deviations, RSD%) of 11% for deionized waters and 12% for well waters, using a spiked level of 5 ng mL⁻¹. The detection limits oscillate from 0.005 ng mL⁻¹ for fluoranthene to 4.4 ng mL⁻¹ for 4-chloro-3-methylphenol, when using an extraction time of 60 min with 20 mL of aqueous sample. The extraction capabilities of the PIL fiber have been compared with the commercial SPME coatings: polydimethylsyloxane (PDMS) 30 μm, PDMS 100 μm and polyacrylate (PA) 85 μm. The PIL fiber is superior to the PDMS 30 μm for all analytes studied. A qualitative study was also carried out to compare among the nature of the coating materials by normalizing the coating thickness. The PIL material was shown to be more efficient than the PDMS material for all analytes studied. The PIL coating was also adequate for nonpolar analytes whereas the PA material was more sensitive for polar compounds.     

Determination of pyrimethanil and kresoxim-methyl in soils by headspace solid-phase microextraction and gas chromatography-mass spectrometry

A method using headspace solid-phase microextraction (HS-SPME) then gas chromatography–mass spectrometry with selected ion monitoring (GC–MS, SIM) has been developed for determination of trace amounts of the fungicides pyrimethanil and kresoxim-methyl in soil and humic materials. Both fungicides were extracted on to a fused-silica fibre coated with 85 m polyacrylate (PA). Response-surface methodology was used to optimise the experimental conditions. For soil samples the linear dynamic range of application was 0.004–1.000 g g^–1 for pyrimethanil and 0.013–1.000 g g^–1 for kresoxim-methyl. The detection limits were 0.001 g g^–1 and 0.004 g g^–1 for pyrimethanil and kresoxim-methyl, respectively. HP-SPME–GC–MS analysis was highly reproducible—relative standard deviations (RSD) were between 6.7 and 12.2%. The method was validated by analysis of spiked matrix samples and used to investigate the presence of pyrimethanil and kresoxim-methyl above the detection limits in soil and humic materials.     

Determination of volatile compounds in Magnolia bark by microwave-assisted extraction coupled to headspace solid-phase microextraction and gas chromatography-mass spectrometry.

A method is described for the determination of volatile compounds in Magnolia bark using microwave-assisted extraction coupled to headspace solid-phase microextraction (MAE-HS-SPME), followed by gas chromatography with mass spectrometry (GC-MS). Parameters affecting the extraction efficiency, such as sampling time and temperature, microwave irradiation power and desorption time, were investigated to achieve the optimal conditions. The result obtained was compared with that of steam distillation; only small differences existed between these two methods. Therefore, the proposed method seems to be a feasible and relatively simple, fast and solvent-free procedure for identification of essential oils in Magnolia bark.     

Measurement of gas-liquid partition coefficient and headspace concentration profiles of perfume materials by solid-phase microextraction and capillary gas chromatography-mass spectrometry

An empirical model describing the relationship between the partition coefficients (K) of perfume materials in the solid-phase microextraction (SPME) fiber stationary phase and the Linearly Temperature Programmed Retention Index (LTPRI) is obtained. This is established using a mixture of eleven selected fragrance materials spiked in mineral oil at different concentration levels to simulate liquid laundry detergent matrices. Headspace concentrations of the materials are measured using both static headspace and SPME-gas chromatography analysis. The empirical model is tested by measuring the K values for fourteen perfume materials experimentally. Three of the calculated K values are within 2-19% of the measured K value, and the other eleven calculated K values are within 22-59%. This range of deviation is understandable because a diverse mixture was used to cover most chemical functionalities in order to make the model generally applicable. Better prediction accuracy is expected when a model is established using a specific category of compounds, such as hydrocarbons or aromatics. The use of this method to estimate distribution constants of fragrance materials in liquid matrices is demonstrated. The headspace SPME using the established relationship between the gas-liquid partition coefficient and the LTPRI is applied to measure the headspace concentration of fragrances. It is demonstrated that this approach can be used to monitor the headspace perfume profiles over consumer laundry and cleaning products. This method can provide high sample throughput, reproducibility, simplicity, and accuracy for many applications for screening major fragrance materials over consumer products. The approach demonstrated here can be used to translate headspace SPME results into true static headspace concentration profiles. This translation is critical for obtaining the gas-phase composition by correcting for the inherent differential partitioning of analytes into the fiber stationary phase.     

Analysis of anatoxin-a using polyaniline as a sorbent in solid-phase microextraction coupled to gas chromatography-mass spectrometry

A simple and sensitive method for determining anatoxin-a in aqueous samples was developed using solid-phase microextraction (SPME) and gas chromatography with mass spectrometry (GC-MS) detection. Three forms of polyaniline (PANI) films and a single form of polypyrrole (PPY) film were prepared and applied for SPME. The extraction properties of these films to anatoxin-a were examined and it was shown that leucoemeraldine form of PANI displayed a better selectivity to this compound. SPME conditions were optimized by selecting the appropriate extraction parameters, including type of coating (leucoemeraldine form of PANI at 32 microm thicknesses), salt concentration (10%, w/v), time of extraction (30 min) and stirring rate (1000 rpm). The calibration curve was linear in the range from 50 to 10,000 ng/ml, with the detection limit (S/N = 3) of 11.2 ng/ml. This method was successfully applied for the analysis of anatoxin-a in the cultured media of two species of cyanobacteria.     

顶空固相微萃取气相色谱-质谱单离子监测法测定水中的多种己二酸酯

采用顶空固相微萃取和气相色谱 质谱单离子监测技术,以己二酸二(1 丁基戊基)酯为内标,对水中的己二酸二乙酯、己二酸二异丁酯、己二酸二丁酯、己二酸二(2 丁氧基乙基)酯、己二酸二(乙基己基)酯进行了测定,考察了盐效应、萃取温度、萃取时间和热解吸时间等因素对方法灵敏度的影响。该方法对5种己二酸酯的检测限量为0.0220～5.49μg L,回收率为86.9%～102.0%,相对标准偏差为1.5%～7.3%。     

Determination of aromatic hydrocarbons in asphalt release agents using headspace solid-phase microextraction and gas chromatography-mass spectrometry

The possibility of quantitative analysis of aromatic hydrocarbons in oil-based asphalt release agents was investigated using headspace solid-phase microextraction (HS-SPME) followed by gas chromatography-mass spectrometry (GC-MS). The target analytes studied were benzene, toluene, ethylbenzene, p-, m-, and o-xylene (BTEX) and 1,3,5-trimethylbenzene and 1,2,4-trimethylbenzene. Experimental parameters influencing HS-SPME efficiency were studied (equilibration time between sample and headspace and between headspace and SPME fiber, sample amount and sample matrice effects). A HS-SPME method using hexadecane as a surrogate matrice was developed. The detection limit was estimated as 0.03-0.08 ppm (w/w) for the target analytes investigated. Good linearity was observed (R2 > 0.999) for all calibration curves at high, medium and low concentration level. The repeatability of the method (RSD, relative standard deviation) was found to be less than 10% (generally less than 5%) in triplicate samples and approximately 2% at eight consecutive tests on one and the same sample. The accuracy of the method given by recovery of spiked samples was between 85 and 106% (generally between 95 and 105%). The HS-SPME method developed was applied to four commercially available asphalt release agents. External calibration and standard addition approaches were investigated regarding accuracy. The results showed that standard addition generates higher accuracy than external calibration. The contents of target aromatic hydrocarbons in the asphalt release agents studied varied greatly from approximately 0.1-700 ppm. The method described looks promising, and could be a valuable tool for determination of aromatic hydrocarbons in different types of organic matrices.     

Purge-assisted headspace solid-phase microextraction combined with gas chromatography-mass spectrometry for determination of chlorophenols in aqueous samples

A simple, economical and very effective method is demonstrated for simultaneous determination of 2,4-dichlorophenol, 2,4,6-trichlorophenol, 2,3,4,6-tetrachlorophenol and pentachlorophenol, in aqueous samples, by using purge-assisted headspace solid-phase microextraction (PA/HS-SPME) coupled to gas chromatography-mass spectrometry (GC-MS). In the new method, purging the sample enhances the removal of the trace chlorophenols without derivatization from the matrices to the headspace. Extraction parameters including extraction temperature, purge gas flow rate and extraction time were systematically investigated. Under optimal conditions, the relative standard deviations (RSDs) were 4-11% at 50 pg/mL and 5-14% at 5 pg/mL, respectively. The recoveries were in the range of 83-114%. Detection limits were determined at the fg level. These results indicate that PA/HS-SPME provides a significant contribution to highly efficient extraction of semi-volatile CPs, especially for pentachlorophenol, which has the smallest Henry's constant and large octanol-water partitioning coefficient. In addition, the proposed method was successfully applied to the analysis of chlorophenols in landfill leachate. New perspectives are opened for headspace extraction of relatively low vapor pressure compounds in complex matrices.