Comparison of headspace solid‐phase microextraction and solvent extraction method for the simultaneous analysis of various soil fumigants in soil or water by gas chromatography–mass spectrometry

The quantity of soil fumigants has increased globally that has focused attention on their environmental behavior. However, simultaneous analysis of traces of fumigant residues is often unreported because analysis methods are not readily available to measure them at low concentrations. In this study, typical solvent extraction methods were compared with headspace solid‐phase microextraction methods. Both methods can be used for simultaneously measuring the concentrations of five commonly used soil fumigants in soil or water. The solvent extraction method showed acceptable recovery (76–103%) and intraday relative standard deviations (0.8–11%) for the five soil fumigants. The headspace solid‐phase microextraction method also showed acceptable recovery (72–104%) and precision rates (1.3–17%) for the five soil fumigants. The solvent extraction method was more precise and more suitable for analyzing relatively high fumigant residue levels (0.05–5 μg/g) contained in multiple soil samples. The headspace solid‐phase microextraction method, however, had a much lower limits of detection (0.09–2.52 μg/kg or μg/L) than the solvent extraction method (5.8–29.2 μg/kg), making headspace solid‐phase microextraction most suitable for trace analysis of these fumigants. The results confirmed that the headspace solid‐phase microextraction method was more convenient and sensitive for the determination of fumigants to real soil samples.     

Magnetic solid‐phase extraction or dispersive liquid–liquid microextraction for pyrethroid determination in environmental samples

The determination of 15 pyrethroids in soil and water samples was carried out by gas chromatography with mass spectrometry. Compounds were extracted from the soil samples (4 g) using solid–liquid extraction and then salting‐out assisted liquid–liquid extraction. The acetonitrile phase obtained (0.8 mL) was used as a dispersant solvent, to which 75 μL of chloroform was added as an extractant solvent, submitting the mixture to dispersive liquid–liquid microextraction. For the analysis of water samples (40 mL), magnetic solid‐phase extraction was performed using nanocomposites of magnetic nanoparticles and multiwalled carbon nanotubes as sorbent material (10 mg). The mixture was shaken for 45 min at room temperature before separation with a magnet and desorption with 3 mL of acetone using ultrasounds for 5 min. The solvent was evaporated and reconstituted with 100 μL acetonitrile before injection. Matrix‐matched calibration is recommended for quantification of soil samples, while water samples can be quantified by standards calibration. The limits of detection were in the range of 0.03–0.5 ng/g (soil) and 0.09–0.24 ng/mL (water), depending on the analyte. The analyzed environmental samples did not contain the studied pyrethroids, at least above the corresponding limits of detection.     

Sensitive determination of amide herbicides in environmental water samples by a combination of solid‐phase extraction and dispersive liquid–liquid microextraction prior to GC–MS

In this paper, solid‐phase extraction (SPE) in combination with dispersive liquid–liquid microextraction (DLLME) has been developed as a sample pretreatment method with high enrichment factors for the sensitive determination of amide herbicides in water samples. In SPE–DLLME, amide herbicides were adsorbed quantitatively from a large volume of aqueous samples (100 mL) onto a multiwalled carbon nanotube adsorbent (100 mg). After elution of the target compounds from the adsorbent with acetone, the DLLME technique was performed on the resulting solution. Finally, the analytes in the extraction solvent were determined by gas chromatography–mass spectrometry. Some important extraction parameters, such as flow rate of sample, breakthrough volume, sample pH, type and volume of the elution solvent, as well as salt addition, were studied and optimized in detail. Under optimum conditions, high enrichment factors ranging from 6593 to 7873 were achieved in less than 10 min. There was linearity over the range of 0.01–10 μg/L with relative standard deviations of 2.6–8.7%. The limits of detection ranged from 0.002 to 0.006 μg/L. The proposed method was used for the analysis of water samples, and satisfactory results were achieved.     

Combined solid‐phase microextraction and high‐performance liquid chromatography with ultroviolet detection for simultaneous analysis of clenbuterol,salbutamol and ractopamine in pig samples

A simple and sensitive method based on the combination of solid‐phase microextraction (SPME) and high‐performance liquid chromatography with ultroviolet detection was developed for the simultaneous determination of clenbuterol, salbutamol and ractopamine in pig samples. Parameters of the SPME procedure affecting extraction efficiency, such as the type of fiber, extraction time, extraction temperature, ion strength, pH of sample and stirring rate, were optimized. The developed method was validated according to the International Conference on Harmonization guidelines. The calibration curves were linear over a range of 0.5–50 µg/L for clenbuterol and ractopamine, and 0.2–20 µg/L for salbutamol. The limits of detection were 0.1 µg/L for clenbuterol, 0.05 µg/L for salbutamol and 0.1μg/L for ractopamine, respectively. The averages of intra‐ and inter‐day accuracy ranged from 79.8 to 92.4%. The intra‐day and inter‐day precision were below 9.6% for the three analytes. This method exhibited the advantages of simplicity, rapidity and low solvent consumption, and was suitable for the monitoring of β₂‐agonists residue in pig samples. Copyright © 2013 John Wiley & Sons, Ltd.     

Application of solid‐phase microextraction in current biomedical research

Extraction of endogenous compounds and drugs and their corresponding metabolites from complex matrices, such as biofluids and solid tissues, requires adequate analytical approach facilitating qualitative and quantitative analysis. To this end, solid‐phase microextraction has been introduced as modern technology that is capable of efficient and high‐throughput extraction of compounds due to its ability to amalgamate sampling, extraction, and pre‐concentration steps, while requiring minimal use of organic solvents. The ability of solid‐phase microextraction to enable analyses on small‐volume biological samples and growing availability of biocompatible solid‐phase microextraction coatings make it a highly useful technology for variety of applications. For example, solid‐phase microextraction is particularly useful for identifying biomarkers in metabolomics studies, and it can be successfully applied in pharmaceutical and toxicological studies requiring the fast and sensitive determination of drug levels, especially those that are present at low levels in biological matrices such as plasma, urine, saliva, and hair. Moreover, solid‐phase microextraction can be directly applied in in vivo studies because this extraction technique is non‐exhaustive and its biocompatible probes offer minimal invasiveness to the analyzed system. In this article, we review recent progress in well‐established solid‐phase microextraction technique for in vitro and in vivo analyses of various metabolites and drugs in clinical, pharmaceutical, and toxicological applications.     

A novel and rapid extraction protocol for sensitive and accurate determination of prochloraz in orange juice samples: Vortex‐assisted spraying‐based fine droplet formation liquid‐phase microextraction before gas chromatography–mass spectrometry

A novel, ecofriendly, and easy extraction and preconcentration method named as vortex‐assisted spraying‐based fine droplet formation liquid‐phase microextraction was proposed for the determination of prochloraz at trace levels in orange juice samples by gas chromatography–mass spectrometry (GC‐MS). In this novel system, extraction solvent is dispersed by the help of spraying apparatus instead of dispersive solvent. Various parameters of the method were carefully optimized to increase signal‐to‐noise ratio of the analyte. Under the optimum chromatographic and extraction conditions, limit of detection and limit of quantification were calculated as 3.2 and 10.8 μg/kg, respectively. Moreover, enhancement in quantification power for the GC‐MS system was determined as 372 folds based on LOQ comparison. Relative recovery results for orange juice samples were found to be between 95.0–107.7% by utilizing matrix matching calibration. Furthermore, the developed method may be used to efficiently and simply extract other organic compounds for their determinations in several matrices.     

Silicon carbide nanomaterial as a coating for solid‐phase microextraction

Silicon carbide has excellent properties, such as corrosion resistance, high strength, oxidation resistance, high temperature, and so on. Based on these properties, silicon carbide was coated on stainless‐steel wire and used as a solid‐phase microextraction coating, and polycyclic aromatic hydrocarbons were employed as model analytes. Using gas chromatography, some important factors that affect the extraction efficiency were optimized one by one, and an analytical method was established. The analytical method showed wide linear ranges (0.1–30, 0.03–30, and 0.01–30 μg/L) with satisfactory correlation coefficients (0.9922–0.9966) and low detection limits (0.003–0.03 μg/L). To investigate the practical application of the method, rainwater and cigarette ash aqueous solution were collected as real samples for extraction and detection. The results indicate that silicon carbide has excellent application in the field of solid‐phase microextraction.     

Thermoelectric‐based temperature‐controlling system for in‐tube solid‐phase microextraction

A temperature‐controlling device for in‐tube solid‐phase microextraction was developed based on thermoelectric cooling and heating. This device can control the temperature of the capillary column from 0 to 100°C by applying a voltage to a Peltier cooler or stainless steel tube. The extraction temperatures for angiotensin I, propranolol, and ranitidine were optimized. In all cases, setting the temperature to 10°C for extraction achieved the best extraction efficiency. Desorption showed minimum peak broadening at 70°C, contributing to better chromatographic performance. Propranolol was selected as a model compound to compare the performance of temperature‐controlled in‐tube solid‐phase microextraction at optimized conditions. Calibration curves exhibited good linearity (R² > 0.999) over the studied range, and the limit of detection and limit of quantification were about three times lower than those obtained at standard conditions (30°C extraction and desorption).     

A dilute-and-inject low-pressure gas chromatography-tandem mass spectrometry method for phthalate determination in extra virgin olive oil

The goal of this study was to develop a method for the determination of nine phthalic acid esters in extra virgin olive oils using low-pressure gas chromatography-triple-quadrupole mass spectrometry. Sample preparation was simple, environmental friendly, and rapid inasmuch that it involved only dilution (< 1 mL of hexane). The low-pressure gas chromatography analyses were performed by using a 5 m wide-bore column. The limit of quantification for the phthalates ranged from 0.06 to 1.14 mg kg⁻¹. Both intra- and interday precisions were measured, with coefficient of variation values ranging from 0.2% to 11.7%. The trueness of the method was measured by evaluating accuracy at the initial stage of the work and after 2 months, with values ranging between −8.7% and 12.1%. Moreover, blind accuracy was comprised between −11.6% and 14.2%. The method involves the use of simplified instrumentation and reduced analysis times (nearly two times faster) compared to a previously published comprehensive two-dimensional gas chromatography-triple-quadrupole mass spectrometry method, leading to a reduction of energy and helium consumption. The approaches were compared in analytical terms and for the environmental impact. In total, 23 olive oil samples were analyzed, with at least one phthalate detected in all but one sample.     

Solid‐phase microextraction Arrow for the volatile organic compounds in soy sauce

A novel solid‐phase microextraction Arrow was used to separate volatile organic compounds from soy sauce, and the results were verified by using gas chromatography with mass spectrometry. Solid‐phase microextraction Arrow was optimized in terms of three extraction conditions: type of fiber used (polydimethylsiloxane, polyacrylate, carbon wide range/polydimethylsiloxane, and divinylbenzene/polydimethylsiloxane), extraction temperature (40, 50, and 60°C), and extraction time (10, 30, and 60 min). The optimal solid‐phase microextraction Arrow conditions were as follows: type of fiber = polyacrylate, extraction time = 60 min, and extraction temperature = 50°C. Under the optimized conditions, the solid‐phase microextraction Arrow was compared with conventional solid‐phase microextraction to determine extraction yields. The solid‐phase microextraction Arrow yielded 6–42‐fold higher levels than in solid‐phase microextraction for all 21 volatile organic compounds detected in soy sauce due to the larger sorption phase volume. The findings of this study can provide practical guidelines for solid‐phase microextraction Arrow applications in food matrixes by providing analytical methods for volatile organic compounds.     

Application of solid‐phase microextraction with gas chromatography and mass spectrometry for the early detection of active moulds on historical woollen objects

The goal of this work was to determine the microbial volatile organic compounds emitted by moulds growing on wool in search of particular volatiles mentioned in the literature as indicators of active mould growth. The keratinolytically active fungi were inoculated on two types of media: (1) samples of wool placed on broths, and (2) on broths containing amino acids that are elements of the structure of keratin. All samples were prepared inside 20 mL vials (closed system). In the first case (1) the broths did not contain any sources of organic carbon, nitrogen, or sulfur, i.e. wool was the only nutrient for the moulds. A third type of sample was historical wool prepared in a Petri dish without a broth and inoculated with a keratinolytically active mould (open system). The microbial volatiles emitted by moulds were sampled with the headspace solid‐phase microextraction method. Volatiles extracted on solid‐phase microextraction fibers were analyzed in a gas chromatography with mass spectrometry system. Qualitative and quantitative analyses of chromatograms were carried out in search of indicators of metabolic activity. The results showed that there are three groups of volatiles that can be used for the detection of active forms of moulds on woollen objects.     

Graphene oxide based in‐tube solid‐phase microextraction combined with liquid chromatography tandem mass spectrometry for the determination of triazine herbicides in water

A novel in‐tube solid‐phase microextraction method based on a graphene oxide coated column was developed for the determination of triazines in waters. This column was prepared by the covalent modification of monolayer graphene oxide sheets onto the inner wall of a fused‐silica capillary. Scanning electron microscopy showed that the thickness of the graphene oxide coating was ～30 nm, with a porous, wrinkled membrane‐like structure. Its performance was evaluated through the extraction of triazines in water. Results showed that the coating was stable for at least 100 replicate extractions, and variety of multi‐columns was less than 10%. Flow rate, loading volume, pH, and ionic strength of samples played an important effect on the extraction. The high extraction efficiency was mainly attributed to π–π stacking and hydrogen bonding interactions. The in‐tube solid‐phase microextraction was used in the determination of triazines with liquid chromatography and tandem mass spectrometry, and the detection limits were 0.0005–0.005 μg/L for five triazine compounds. Further, the method was applied to the analysis of triazine herbicides in real samples including tap water, sea water, and river water, and the recoveries were 82.8–112.0, 85.4–110.5, and 81.6–105.9%, respectively, with RSDs of 2.7–7.1%.     

Ultrasensitive determination of highly polar trimethyl phosphate in environmental water by molecularly imprinted polymeric fiber headspace solid‐phase microextraction

A sensitive, accurate, and cost effective method for the quantification of trimethyl phosphate, which is highly polar and volatile, in environmental water is presented. Trimethyl phosphate was headspace solid‐phase microextracted on a molecularly imprinted polymeric fiber, and then the fiber was thermally desorbed in the gas chromatograph injector, and the compound was determined. The trimethyl phosphate imprinted polymeric fiber was prepared by copolymerization in a fused silica capillary tube and obtained by removal of the wall of fused silica capillary tube. The monolithic fiber displayed good selectivity toward trimethyl phosphate among its structural analogues. It was thermally stable up to 320°C so that it can withstand the high temperature of the gas chromatograph injector for desorption. The factors influencing the performance of its headspace solid‐phase microextraction were studied. Under the optimal conditions, the method for quantification of trimethyl phosphate in environmental water was well developed. It exhibited significant linearity, the lowest limit of quantification to date, and good recoveries. Using this method, trimethyl phosphate was detected in five out of seven environmental water samples at concentration levels from 0.28 to 1.22 μg/L, illustrating the heavy pollution of trimethyl phosphate in environmental water.     

Ultrasound‐assisted magnetic dispersive solid‐phase microextraction: A novel approach for the rapid and efficient microextraction of naproxen and ibuprofen employing experimental design with high‐performance liquid chromatography

A simple, rapid, and sensitive method for the determination of naproxen and ibuprofen in complex biological and water matrices (cow milk, human urine, river, and well water samples) has been developed using ultrasound‐assisted magnetic dispersive solid‐phase microextraction. Magnetic ethylendiamine‐functionalized graphene oxide nanocomposite was synthesized and used as a novel adsorbent for the microextraction process and showed great adsorptive ability toward these analytes. Different parameters affecting the microextraction were optimized with the aid of the experimental design approach. A Plackett–Burman screening design was used to study the main variables affecting the microextraction process, and the Box–Behnken optimization design was used to optimize the previously selected variables for extraction of naproxen and ibuprofen. The optimized technique provides good repeatability (relative standard deviations of the intraday precision 3.1 and 3.3, interday precision of 5.6 and 6.1%), linearity (0.1–500 and 0.3–650 ng/mL), low limits of detection (0.03 and 0.1 ng/mL), and a high enrichment factor (168 and 146) for naproxen and ibuprofen, respectively. The proposed method can be successfully applied in routine analysis for determination of naproxen and ibuprofen in cow milk, human urine, and real water samples.     

Polydopamine‐coated cotton fibers as the adsorbent for in‐tube solid‐phase microextraction

Polydopamine was coated onto cotton fibers as the adsorbent to improve the extraction efficiency. Polydopamine‐coated cotton fibers were placed into a polyetheretherketone tube for in‐tube solid‐phase microextraction. To develop an online analysis system, the extraction tube was connected with high‐performance liquid chromatography. The tube was evaluated with five estrogenic analytes, and the extraction and desorption conditions were optimized to get high extraction efficiency. Under the optimum conditions, the enrichment factors of five analytes were 143–1745. An online analysis method was established, it had large linear ranges (0.10–40 and 0.16–40 μg/L), low limits of detection (0.03, 0.05 μg/L) and satisfactory repeatability (≤3.2%). The analysis method was applied to detect targets in the real samples like as hot water in new plastic cup and tap water. The relative recoveries spiked at 1 and 5 μg/L in these samples were investigated and the results were in the range of 83.7–109%.     

Multivariate analysis of the volatile components in tobacco based on infrared‐assisted extraction coupled to headspace solid‐phase microextraction and gas chromatography‐mass spectrometry

A novel infrared‐assisted extraction coupled to headspace solid‐phase microextraction followed by gas chromatography with mass spectrometry method has been developed for the rapid determination of the volatile components in tobacco. The optimal extraction conditions for maximizing the extraction efficiency were as follows: 65 μm polydimethylsiloxane‐divinylbenzene fiber, extraction time of 20 min, infrared power of 175 W, and distance between the infrared lamp and the headspace vial of 2 cm. Under the optimum conditions, 50 components were found to exist in all ten tobacco samples from different geographical origins. Compared with conventional water‐bath heating and nonheating extraction methods, the extraction efficiency of infrared‐assisted extraction was greatly improved. Furthermore, multivariate analysis including principal component analysis, hierarchical cluster analysis, and similarity analysis were performed to evaluate the chemical information of these samples and divided them into three classifications, including rich, moderate, and fresh flavors. The above‐mentioned classification results were consistent with the sensory evaluation, which was pivotal and meaningful for tobacco discrimination. As a simple, fast, cost‐effective, and highly efficient method, the infrared‐assisted extraction coupled to headspace solid‐phase microextraction technique is powerful and promising for distinguishing the geographical origins of the tobacco samples coupled to suitable chemometrics.     

Monitoring of the influence of long‐term oxidative stress and ischemia on the condition of kidneys using solid‐phase microextraction chemical biopsy coupled with liquid chromatography–high‐resolution mass spectrometry

The limiting factor in conventional quality assessments of transplanted organs, namely the invasiveness of tissue sample collection, has prompted much research on the field of transplantology to focus on the development of alternative evaluation methods of organ quality. In the present project, we undertake the challenge to address the need for a new analytical solution for graft quality assessments by using a novel metabolomic diagnostic protocol based on low‐invasive solid‐phase microextraction. Solid‐phase microextraction probes of ca. 0.2 mm coated with 4 mm long mixed‐mode extraction phase were inserted into rabbit kidneys immediately following euthanasia and after 2, 4, 6, and 21 h of preservation. Liquid chromatography–mass spectrometry analysis of the extracts was performed with the use of a reversed phase column and a Q‐Exactive Focus mass spectrometer operated in positive ionization mode. Statistical analysis of significantly changing compounds revealed metabolic profile changes in kidneys induced by ischemia and oxidative stress as a function of the duration of cold storage. The most pronounced alterations were reflected in levels of essential amino acids and purine nucleosides. Our findings demonstrate that the proposed approach may be successfully used to monitor changes in the metabolic profile of organs over time of preservation.     

Basalt fibers functionalized with gold nanoparticles for in‐tube solid‐phase microextraction

Basalt fibers were functionalized with gold nanoparticles and characterized by scanning electron microscopy and energy‐dispersive X‐ray spectroscopy. An in‐tube solid‐phase microextraction device was developed by packing the functionalized basalt fibers in a polyether ether ketone tube. The device was connected into high performance liquid chromatography equipment with a diode array detector to build online enrichment and analysis system. Eight polycyclic aromatic hydrocarbons were used as model analytes, important factors including sampling rate, sampling volume, organic solvent content in sample, and desorption time were investigated. Linear range (0.01–20 μg/L), detection limits (0.003–0.015 μg/L), and enrichment factors (130–1628) were given by the online analysis method. Relative standard deviations (n = 5) of extraction repeatability on one tube and tube‐to‐tube repeatability were less than 5.2 and 14.7%, respectively. The analysis method was applied to detect polycyclic aromatic hydrocarbons in environmental water samples, and relative recoveries ranged from 87 to 128%.     

Carbon nanospheres as solid‐phase microextraction coating for the extraction of polycyclic aromatic hydrocarbons from water and soil samples

A solid‐phase microextraction with carbon nanospheres coated fiber coupled with gas chromatographic detection was established for the determination of eight polycyclic aromatic hydrocarbons (naphthalene, biphenyl, acenaphthene, fluorine, phenanthrene, anthracene, fluoranthene, and pyrene) in water and soil samples. The experimental parameters (extraction temperature, extraction time, stirring rate, headspace volume, salt content, and desorption temperature) which affect the extraction efficiency were studied. Under the optimized conditions, good linearity between the peak areas and the concentrations of the analytes was achieved in the concentration range of 0.5‐300 ng/mL for water samples, and in the concentration range of 6.0‐2700 ng/g for soil samples. The detection limits for the analytes were in the range of 0.12‐0.45 ng/mL for water samples, and in the range of 1.53‐2.70 ng/g for soil samples. The method recoveries of the polycyclic aromatic hydrocarbons for spiked water samples were 80.10‐120.1% with relative standard deviations less than 13.9%. The method recoveries of the analytes for spiked soil samples were 80.40‐119.6% with relative standard deviations less than 14.4%. The fiber was reused over 100 times without a significant loss of extraction efficiency.     

Resorcinol–formaldehyde aerogel coating for in‐tube solid‐phase microextraction of estrogens

Resorcinol–formaldehyde aerogel coating was in situ prepared on the surface of basalt fibers. The aerogel coating is uniformly modified onto basalt fibers, and it is very porous according to the characterization by using scanning electron microscopy. An extraction tube was prepared for in‐tube solid‐phase microextraction by placing the aerogel‐coated basalt fibers into a polyetheretherketone tube. To evaluate the extraction performance toward five estrogenic compounds, the tube was connected with high performance liquid chromatography, the important extraction and desorption conditions were investigated. An online analytical method for detection of estrogens was developed and presented low limits of detection (0.005–0.030 µg/L), wide linear ranges (0.017–20, 0.033–20, and 0.099–20 µg/L), good linearity (r > 0.9990), and satisfactory repeatability (relative standard deviation < 2.7%). The method was successfully applied to detect trace estrogens in real water samples (bottled pure water and bottled mineral water), satisfactory recoveries were ranged from 80 to 125% with two spiking levels of 2 and 6 µg/L.