Phase Microextraction Fiber Research Articles

Preparation of covalent organic framework based on room temperature solution-suspension approach and its application to solid-phase microextraction of pyrethroids in tea

拟除虫菊酯(PYs)类农药被广泛用于茶园病虫害的防治。随着国内外对进出口茶叶中农药残留限量的要求日益严格,我国迫切地需要开发能应用于检测茶叶中痕量PYs的方法。研究通过简单、温和的溶液悬浮法(SSA),在室温下制备了共价有机骨架(COF)材料TpBD,该材料具有优异的热/化学稳定性、较高的孔隙度和比表面积。通过简单物理黏附的方法,将TpBD制备成固相微萃取(SPME)纤维。将准备好的纤维应用于固相微萃取技术并与气相色谱-串联质谱(GC-MS/MS)联用,建立用于检测PYs的高灵敏分析方法。该方法对氟氯氰菊酯、氯氰菊酯、氟氰菊酯、氰戊菊酯和溴氰菊酯的富集倍数为702~2687,并表现出低的检出限(0.1~0.5 ng/L)、宽的线性范围(0.2~800 ng/L)、良好的线性关系(相关系数≥0.9991)、可接受的重复性(RSD≤11.0%, n=3)。将所建立的方法用于实际绿茶和乌龙茶样品中PYs残留量的检测,并成功地从实际茶样中检测出5种痕量PYs,并且具有满意的回收率(80.2%~109.5%)。实验结果表明,所建立的分析方法适用于茶叶中PYs农药残留量的分析和检测。此外,通过SSA成功地制备了TpBD材料,证实了该方法具有较好的普适性,具有简便合成其他COFs材料的潜力。

Preparation and characterisation of polypyrrole – carbon nanomaterial composite solid-phase microextraction fibres and their applications to the determination of fungicide residues in grape juice samples

ABSTRACT Present study describes the use of a lab-made polypyrrole (PPy) coated solid phase microextraction (SPME) fibres modified with carbonaceous nanomaterials for effective adsorption of volatile fungicides used in vineyards for subsequent determination by gas chromatography coupled with a mass spectrometer. The SPME fibres were fabricated electrochemically by dipping a stainless steel wire in a cell containing pyrrole monomer where the polymeric film was coated on the wire by cycling the potential between −0.5 and 2.0 V at a rate of 50 mV s−1. Then, the procedure was repeated in the presence of multi-walled carbon nanotubes (MWCNTs) or graphene (Gr) nanoplates dispersed in tartrate solution. The coated fibres were attached to a holder for subsequent headspace extraction of volatile fungicides in grape juice samples. Initial studies were conducted with commercial fibres adoptable to a fully automated system and optimal conditions were studied by using an 85 µm PA fibre. Then, the fabricated fibres have been tested manually under optimised conditions for unbiased comparison. Overall results have suggested that PPy-MWCNT-SPME and PPy-Gr-SPME have given the comparable results with commercial fibres in the concentration range of 1.0–50 ng mL−1 by allowing the determination of these fungicides at LOQ levels varied in the range of 0.55–6.94 ng mL−1 ranges. In comparison to the literature values, more results that are sensitive were obtained with these two fibres with satisfactory recovery values without any solvent consumption or labour-intensive pre-treatment processes.

Polyoxometalate-based ionic liquid coating for solid phase microextraction of triazole pesticides in water samples

ABSTRACTIn the study, the polyoxometalate-based ionic liquid (POM-IL) was prepared. The prepared nanomaterial was immobilized onto a stainless steel wire for fabrication of the solid phase microextraction (SPME) fiber. The applicability of this coating was assessed employing a laboratory-made SPME device and gas chromatography with mass spectrometry (GC–MS) for the extraction of six triazole pesticides (penconazole, hexaconazole, diniconazole, tebuconazole, triticonazole, and difenconazole) from the headspace of aqueous samples. A series of parameters that affect the performance of microextraction, such as fiber coating, extraction time, stirring rate, ionic strength, pH, desorption temperature, and desorption time, were thoroughly investigated. In optimum conditions, the repeatability for one fiber (n = 3), expressed as relative standard deviation, was between 4.3% and 8.3% for the test compounds. The detection limits for the studied compounds were between 7 and 40 pgmL−1.

Analysis of volatile compounds in chestnut using solid-phase microextraction coupled with GC-MS

In this work volatile compounds of raw chestnuts (peeled and unpeeled) were evaluated. Samples of chestnuts (Castanea sativa Mill.) were obtained from the area of the Una-Sana canton (Bosnia and Herzegovina) during the seasonal harvest. Freshly harvested chestnuts were ground with a blender. A portion of chestnut was manually peeled before grinding. The samples were analyzed using solid phase microextraction (SPME) fibers in conjunction with gas chromatography/mass spectrometer (GC-MS). Compounds were identified on the basis of their retention times using the searchable EI-MS spectra library (NIST02). Volatile fraction was composed of 34 and 31 main compounds for unpeeled and peeled chestnuts respectively. Among them, 25 peaks were found in both analyzed samples. The compounds that contribute to the volatile profile of unpeeled fruit were mainly alcohols (53.99% of total areas), followed by other components (28.16%), ketones (6.70%) and esters (5.59%). The main volatile compounds found in raw peeled chestnuts were also alcohols (52.80%), followed by other components (15.47%), acids (12.40%) and ketones (11.93%). The main compounds of the volatile fraction extracted from unpeeled chestnuts samples were styrene (22.64%), ethanol (14.19%), 1-octanol (13.06%) and 3-methyl-1-butanol (5.27%), whereas ethanol (20.61%), 1-octanol (18.40%), acetic acid (11.01%), 2-pentylfuran (10.26%), 1-hexanol (7.00%) and 2-heptanone (5.86%) were identified as the main volatile components of raw peeled chestnuts. This study indicates that peeling of chestnuts affected the chemical composition of volatile compounds.

Initial study of three different pathogenic microorganisms by gas chromatography-mass spectrometry

Background: Diagnoses of respiratory tract infections usually happen in the late phase of the disease and usually result in reduction of the pathogen load after broad-spectrum antibiotic therapy, but not in eradication of the pathogen. The development of a non-invasive, fast, and accurate method to detect pathogens has always been of interest to researchers and clinicians alike. Previous studies have shown that bacteria produce organic gases. The current study aimed to identify the volatile organic compounds (VOCs) produced by three respiratory tract pathogens, including Staphylococcus aureus, Escherichia coli and Candida albicans.Methods: The VOCs produced were identified by gas chromatography-mass spectrometry (GC-MS), with prior collection of microbial volatile compounds using solid phase microextraction (SPME) fiber. The volatile compounds were collected by obtaining bacterial headspace samples. Results: Results showed that these three organisms have various VOCs, which were analyzed under different conditions. By ignoring common VOCs, some species-specific VOCs could be detected. The most important VOC of E. coli was Indole, also some important VOCs produced by S. aureus were 2,3-Pentandione, cis-Dihydro-α-terpinyl acetate, 1-Decyne, 1,3-Heptadiene-3-yne, 2,5-dimethyl Pyrazine, Ethyl butanoate and Cyclohexene,4-ethenyl furthermore, most of identified compounds by C. albicans are alcohols. Conclusions: The detection of VOCs produced by infectious agents maybe the key to make a rapid and precise diagnosis of infection, but more comprehensive studies must be conducted in this regard.

Solid Phase Microextraction (SPME) Fibers: in situ Measurements of Endocrine Disrupting Chemicals in Seawater

Solid Phase Microextraction (SPME) Fibers: in situ Measurements of Endocrine Disrupting Chemicals in Seawater

Modified Coated Copper Wire as a New Fiber for SPME-GC Analysis of Some Polycyclic Aromatic Hydrocarbons

In this study for the first time, a novel copper Solid Phase Microextraction (SPME) fiber has been introduced for removal of naphthalene, phenanthrene and anthracene from aqueous solution. Copper was used as a solid support, which was at first coated by 3-mercaptopropyltrimethoxysi- lane. A stationary phase of oxidized multi walled carbon nanotube (MWCNTs)) was bonded to the surface of the copper wire. The developed SPME was characterized by IR and Scanning Electron Microscopy (SEM) and coupled to gas chromatography for separation of the analytes. Stability of the fiber, the effect of coating thickness and recovery time were optimized. The MWCNTs film thickness was about 5 μm which was perfect for a rapid mass transfer. The detection limits were at the range of 0.005 to 0.1 μg·L-1. The calibration curves were linear R2 > 0.9813 in the range of 0.01 to 5 μg·L-1. The method has been successfully applied for real samples with standard addition of 5 μL-1 of each sample. Stability study of the fiber to acid and alkali shows that it can be used for more than 50 times.

Rapid Separation of Elemental Species by Fast Multicapillary Gas Chromatography with Multichannel Optical Spectrometry Detection following Headspace Solid Phase Microextraction

A method for conducting fast and efficient gas chromatography based on short multicapillaries in straight alignment combined with atomic emission detection was developed for field analysis. The strategy enables for speciation analysis of organometallic compounds. The analytes are simultaneously ethylated and preconcentrated on a solid phase microextraction (SPME) fiber placed in the headspace over the sample for 25 min. The ethylated species are then completely separated and selectively quantified within 25 s under isothermal conditions. A new miniaturized speciation analyzer has been constructed and evaluated. The system consists of a GC injection port and a lab-made miniaturized GC unit directly coupled with miniaturized plasma excitation source. The emitted light is transferred via optical fiber and registered with a miniaturized charged coupled device (CCD) based spectrometer. Working parameters for multicapillary column gas chromatography with atomic emission detector, including carrier gas flow rate, desorption temperature, and GC column temperature, were optimized to achieve good separation of analytes. Basic investigations of the fundamental properties of 5 cm-long multicapillary column, to evaluate its potential and limitations as a rapid separation unit, are presented. The adaptation of the technique for use with a SPME system and with a multichannel element-selective plasma-emission detector is highlighted.

In vivo extraction of volatile organic compounds (VOCs) from Micro-Tom tomato flowers with multiple solid phase microextraction (SPME) fibers

The in vivo headspace extraction of volatile organic compounds from Micro-Tom tomato flowers was investigated using multiple solid phase microextraction (SPME) fibers of different properties to maximize the extraction selectivity for a nontargeted analysis. The three fibers used in this work were polydimethylsiloxane (PDMS), PDMS/divinylbenzene (DVB), and carboxen (CAR)/PDMS. Two sources for tomato flowers were used: Micro-Tom wild type (WT) and transgenic Micro-Tom overexpressing the carotenoid cleavage deoxygenase 1 gene. Gas chromatography–mass spectrometry (GC–MS) results demonstrated that the largest amounts of volatile organic compounds (VOCs) were observed with the PDMS/DVB fiber for both wild type and transgenic plants, but the CAR/PDMS and PDMS fibers contributed to the detection of selective compounds. Data revealed the presence of 45 VOCs from transgenic plants and 35 from the wild type when all three fibers were used together. Of the total VOCs identified, 30 were common to both types of plants, but 15 were specific to the transgenic and 5 to the wild type plants. The compounds identified from Micro-Tom flowers were mainly monocyclic and bicyclic monoterpenes and sesquiterpenes, with one alkyl benzene compound. The bicyclic monoterpenes, (1R)-α-pinene, (1S)-α-pinene, and β-pinene, were found to be the most abundant molecules present in both wild type and transgenic plants. The overall advantage of maximizing the discovery of VOCs based on the selectivity differences with three SPME fibers was evident. Such a benefit is important in the nontargeted analysis of transgenic plants for detecting the production of unexpected compounds.

Kesan Suhu Pengeringan dan Darjah Pengilangan Terhadap Kandungan 2-Acetyl-1 Pyrroline (2-AP) di dalam Beras Wangi

Investigations on the main compound of aroma rice, which is 2-Acetyl-1-pyrroline (2-AP), treated under different drying temperatures and milling degree was carried out. The results showed that the 2-AP was higher when paddy dried at 45°C, compared to 40°C and 50°C. The compound was extracted and absorbed using Solid Phase-Micro Extraction (SPME) fiber and analysed with gas chromatography-mass spectrometry (GC-MS). Milling degree is determined by percent of bran removal. High bran removal means higher milling degree. The finding showed that the 2-AP was higher in rice with higher percent bran removal.

Recent Progress, Challenges and Prospects in Monitoring Plastic-Derived Xenoestrogens Using Molecularly Imprinted Sorbents

Indoor and outdoor exposure to plastic-derived xenoestrogens, such as phthalates and phenolic compounds, can adversely affect endocrine and reproductive systems in humans and wildlife. To accomplish the extraction of plastic-derived xenoestrogens from environmental samples, molecularly imprinted polymers (MIPs) have been proved to be selective, efficient, and reliable sorbents. Despite some problems associated with the use of MIPs as sorbents, these have been found to be of considerable interest due to their advantages of selectivity, easy synthetic procedures, and better stability over commercially available solid sorbents. Modifications in their synthetic strategies are continuously in progress and new approaches are being made through graphene oxide substrates, nanostructured platforms, nanoferrites, cryogels, and co-electropolymerization to design better sorbents. Apart from this, efforts to create molecularly imprinted solid phase microextraction (SPME) fibers have also been successful in improving the efficiency of the methodology. In future, the use of MIPs developed from advanced synthetic strategies, or as sorbents for more robust techniques like SPME and microextraction on packed sorbents, will add new horizons to explore the potential of MIPs in the field of plastic-derived xenoestrogens. This review presents various challenges, as well as progress and prospects associated with the extraction of plastic-derived phthalates and phenolic compounds using molecularly imprinted sorbents.

인공타액처리에 의한 수삼의 향기성분 변화 분석

The volatile constituents of the fresh roots of Panax ginseng C.A. Meyer have been investigated after treatment with artificial saliva and analysed by gas chromatography-mass spectrometry (GC-MS) using solid phase microextraction (SPME) fiber. Twenty peaks were detected in fresh ginseng, 5 of them were unknown peak, and mainly hydrocarbon components (α-pinene, β-pinene, myrcene, limonene, β-panasinsene, β-elemene, β-gurjunene, trans-caryophyllene, α-gurjunene, α-panasinsene, α-neoclovene, trans-β-farnasene, α-humulene, β-neoclovene, α-selinene, β-selinene, bycyclogermacrene) were detected. It's area percentage was increased about 10% in the fresh ginseng added artificial saliva during 40 minutes.

Development of an Analytical Protocol for Forensic Identification of Chemical Warfare Agent Surrogates

An analytical protocol for forensic identification of chemical warfare agent surrogates in various sample media is developed. This protocol can be implemented on site or in a mobile laboratory, based on a quick sample extraction procedure and a subsequent gas chromatography/mass spectrometry (GC/MS) analysis. The surrogates in this work include 2-chloroethyl ethyl sulfide (CEES), dimethyl methyl phosphonate (DMMP), 2-(butylamino) ethanethiol (BAET), pinacolyl methyl phosphonate (PMP), and diethyl phosphoramidate (DEPA) that are simulants of mustard gas, sarin, VX (O-Ethyl S-2-diisopropylaminoethyl methylphosphonothiolate), soman, and tabun, respectively. The target analytes in headspace or air sample are sampled by the solid phase microextraction (SPME) fibers and all surrogates are easily detected by GC/MS analysis. The neat vapor is also directly analyzed by a portable MS through a membrane inlet but only the more volatile CEES and DMMP are detectable and correctly identified. The stability of surrogates in acetone is monitored in the preparation of standard solution. All surrogates are relatively stable in acetone with the exception of BAET, which is found to degrade quickly in water and other organic solvents (e.g., acetone, methanol, ethanol, hexane). Extraction of water and soil samples is also investigated in this study. In analyzing water sample spiked with the surrogates, it is found that SPME does not offer any advantage over direct aqueous injection into the GC/MS. CEES readily hydrolyzes in water to form 2-(ethylthio)-ethanol. Soil samples are extracted by acetone and the raw extracts are analyzed without any concentration, and all surrogates are detectable at 5–10 ppm level for CEES, DMMP, and DEPA. An actual case study is carried out using SPME to detect the presence of surrogate vapor inside a laboratory refrigerator in which they are stored.

Gas Chromatographic Analysis of Organic Marker Compounds in Fine Particulate Matter Using Solid-Phase Microextraction

A gas chromatographic method that uses solid-phase microextraction for analysis of organic marker compounds in fine particulate matter (PM2.5) is reported. The target marker compounds were selected for specificity toward emission from wood smoke, diesel or gasoline combustion, or meat cooking. Temperature-programmed volatilization analysis was used to characterize the thermal stabilities and volatile properties of the compounds of interest. The compounds were thermally evaporated from a quartz filter, sorbed to a solid phase microextraction (SPME) fiber, and thermally desorbed at 280 °C in a gas chromatograph injection port connected via a DB 1701 capillary separating column. Various experimental parameters (fiber type, time, and temperature of sorption) were optimized. It was found that high extraction yield could be achieved using a polyacrylate fiber for polar substances, such as levoglucosan, and a 7-µm polydimethylsiloxane (PDMS)-coated fiber for nonpolar compounds, such as hopanes and polyaromatic hydrocarbon. A compromise was made by selecting a carboxen/PDMS fiber, which can simultaneously extract all of the analytes of interest with moderate-to-high efficiency at 180 °C within a 30-min accumulation period. The optimized method was applied to the determination of levoglucosan in pine wood combustion emissions. The simplicity, rapidity, and selectivity of sample collection with a polymer-coated SPME coupled to capillary gas chromatography (GC) made this method potentially useful for atmospheric chemistry studies.

A Gas Sample Pre‐concentration Device Based on Solid Phase Microextraction (SPME) and Temperature Programmed Desorption (TPD)

A sample pre‐concentration device, based on solid phase microextraction (SPME) fiber and temperature programmed desorption (TPD), was developed and tested in the analysis of volatile organic compounds. The pre‐concentrator device consists of a low dead volume quartz tube that houses the SPME fiber during the extraction/ desorption steps, a Ni:Cr heating element, and a programmable power supply. Compounds are extracted from air into the SPME fiber according to their affinity and solubility to the fiber material. Following this extraction step, samples are desorbed by a pre‐programmed temperature ramp for their subsequent detection. The SPME fiber was exposed and sample extracted for a pre‐determined amount of time (1 min, in this work). Because of the limited specificity of the stationary phase in SPME fibers towards the analyte, background interfering compounds are unavoidably co‐extracted during this process. A TPD step was then applied to sequentially desorb and detect analytes and interferences. The temperature ramp was designed so as to maximize temporal resolution between target analytes and background chemical interferences. The SPME/TPD pre‐concentrator was tested with a binary chemical system consisting of dimethyl‐methylphosphate (DMMP, a chemical warfare simulant) and toluene (a common commercial solvent). Analyte desorption was monitored on‐line with a quadrupole ion trap mass spectrometer. Five SPME fibers with different stationary phases were tested: polyacrylate (PA), polydimethylsiloxane (PDMS), carboxen–polydimethylsiloxane (CAR/PDMS), polydimethylsiloxane–divinylbenzene (PDMS/DVB), and carbowax/divinylbenzene (CW/DVB). Best results were obtained with the PDMS (100 µm) fiber. Two other SPME fibers, CW/DVB and CAR/PDMS, along with the TPD step, were also successful in the temporal resolution the of DMMP and toluene. The approach is rapid in that the extraction and desorption steps take less than 3 min. Implications and applications of the SPME/TPD system as a sample pre‐concentration step in handheld devices are discussed. The simplicity of the device makes it amenable to miniaturization by available microfabrication techniques.

DYNAMIC AIR SAMPLING OF VOLATILE ORGANIC COMPOUNDS USING SOLID PHASE MICROEXTRACTION

A new dynamic air sampling system was devised and evaluated in conjunction with solid phase microextraction (SPME) fiber materials for extracting odor-causing volatile organic compounds (VOCs) present in swine building environments. Utilizing a standard solution consisting of 11 compounds (i.e., volatile fatty acids, indoles, and phenol), sampling times, volumes, and flow rates were adjusted to establish optimal extraction conditions. Results indicated that the sampling system was effective with the Carboxen/Polydimethylsiloxane (CAR/PDMS) fiber in extracting all 11 standard compounds. The best sampling conditions for the extraction were a 100-mL sampling vial subjected to a continuous flow of 100 mL/min for 60 min. The gas chromatographic analysis showed that the reproducibility was within acceptable ranges for all compounds (RSD=4.24–17.26% by peak areas). In addition, field tests revealed that the sampling system was capable of detecting over 60 VOCs in a swine house whose major components were identified by gas chromatography–mass spectrometry (GC–MS) and by their retention times as volatile fatty acids, phenols, indole, and skatole. The field tests also showed that considerably different levels of VOCs were present in various parts of the swine building.

A case study of indoor pollution by Chinese cooking

Indoor air monitoring is very important for two main reasons: the long time spent inside buildings in Western life and the possible link between exposure to volatile organic compounds (VOC), even at low concentrations, and health effects. We consider here a case of indoor pollution, due to Chinese cooking. Chinese cooking includes frying in woks, special pans in which foods and fats are heated to temperatures (240–280°C) at which some molecules decompose to volatile products. Two different methods for qualitative analysis of these products were tested, both using GC‐MS for separation and identification. With the first method air is sampled with carbon molecular sieve cartridges and analytes eluted with an appropriate solvent. The second method, the most successful, involves direct exposure of a solid phase microextraction (SPME) fiber in the polluted area, which provides both sampling and concentration of analytes. SPME coupled with GC‐MS is a powerful technique for the identification of VOC responsible for indoor air pollution.