Determination of Xenoestrogens Alkylphenols in Oyster and Snail Tissues by Extractive Steam Distillation and Gas Chromatography‐Mass Spectrometry

A simple and sensitive method is presented for the determination of two well‐known xenoestrogens alkylphenols (4‐tert.‐octylphenol (4‐t‐OP) and 4‐nonylphenol isomers (4‐NPs)) in oysters and snails. The method involves extraction of the sample by a modified Nielson‐Kryger steam distillation extraction, and the alkylphenols were then identified and quantitated by gas chromatography‐mass spectrometry (GC‐MS) in selected ion monitoring (SIM) mode. The quantitation limit of this method was less than 20 ng/g in 0.5 g (dry weight) of the samples. The perfect applicability of the steam distillation extraction method for 4‐t‐OP and 4‐NPs was determined after testing it with spiked and real samples. Recovery of 4‐t‐OP and 4‐NPs in spiked tissue samples was above 88% while relative standard deviation (RSD) ranged from 7 to 14%. 4‐tert.‐octylphenol and 4‐nonylphenol isomers are ubiquitous in oysters and snails with the concentrations of 4‐t‐OP and 4‐NPs ranging from 70 to 820 ng/g and from 210 to 2750 ng/g (dry weight), respectively.     

Isotope dilution gas chromatography with mass spectrometry for the analysis of 4‐octyl phenol, 4‐nonylphenol,and bisphenol A in vegetable oils

By the combination of solid‐phase extraction as well as isotope dilution gas chromatography with mass spectrometry, a sensitive and reliable method for the determination of endocrine‐disrupting chemicals including bisphenol A, 4‐octylphenol, and 4‐nonylphenol in vegetable oils was established. The application of a silica/N‐(n‐propyl)ethylenediamine mixed solid‐phase extraction cartridge achieved relatively low matrix effects for bisphenol A, 4‐octylphenol, and 4‐nonylphenol in vegetable oils. Experiments were designed to evaluate the effects of derivatization, and the extraction parameters were optimized. The estimated limits of detection and quantification for bisphenol A, 4‐octylphenol, and 4‐nonylphenol were 0.83 and 2.5 μg/kg, respectively. In a spiked experiment in vegetable oils, the recovery of the added bisphenol A was 97.5–110.3%, recovery of the added 4‐octylphenol was 64.4–87.4%, and that of 4‐nonylphenol was 68.2–89.3%. This sensitive method was then applied to real vegetable oil samples from Zhejiang Province of China, and none of the target compounds were detected.     

Graphene oxide coated capillary for the analysis of endocrine‐disrupting chemicals by open‐tubular capillary electrochromatography with amperometric detection

A graphene oxide‐coated capillary was fabricated by using 3‐aminopropyltriethoxysilane as the cross‐linking agent. It was used for the separation and detection of three endocrine‐disrupting chemicals, including bisphenol A, 4‐nonylphenol, and 4‐octylphenol by capillary electrochromatography. Due to the hydrophobicity, hydrogen bonding, and π–π interaction between graphene oxide and the analytes, the three analytes could be well separated in pH = 11.0, 20 mmol/L Na₂B₄O₇‐NaOH/methanol mobile phase (50:50, v/v) within 950 s. After preconcentration, the detection limits were 6.7 × 10^?10, 3.3 × 10^?9, and 6.7 × 10^?10 mol/L (S/N = 3) for bisphenol A, nonylphenol, and octylphenol, respectively. The developed method was successfully applied to the determination of the above analytes in water samples. The satisfactory result demonstrated that the graphene oxide coated capillary used in capillary electrochromatography with amperometric detection was convenient to prepare, highly stable, and had good reproducibility.     

Application of solid-phase microextraction and gas chromatography-mass spectrometry for the determination of chlorophenols in leather

This paper proposes a new analytical procedure based on the headspace solid‐phase microextraction (HS‐SPME) technique and gas chromatography‐selected ion monitoring‐mass spectrometry (GC‐SIM‐MS) for the determination of 16 phenols extracted from leather samples. The optimized conditions for the HS‐SPME were obtained through two experimental designs – a two‐level fractional factorial design followed by a central composite design – using the commercial SPME fiber polyacrylate 85 μm (PA). The best extraction conditions were as follows: 200 μL of derivatizing agent (acetic anhydride), 20 mL of saturated aqueous NaCl solution and extraction time and temperature of 50 min and 75°C, respectively. All optimized conditions were obtained with fixed leather sample mass (250 mg), vial volume (40 mL) and phosphate buffer pH (12) and concentration (50 mmol/L). Detection limits ranging from 0.03 to 0.20 ng/g, and relative standard deviation (RSD) lower than 10.23% (n=6) for a concentration of 800 ng/g (chlorophenols) and 1325 ng/g (2‐phenylphenol) in the splitless mode were obtained. The recovery was studied at three concentration levels by adding different amounts of phenols to the leather sample and excellent recoveries ranging from 90.0 to 107.2% were obtained. The validated method was shown to be suitable for the quantification of phenols in leather samples, as it is simple, relatively fast and sensitive.     

Analysis of phenolic xenoestrogens by pressurized CEC with amperometric detection

A new method, pressurized CEC with end‐column amperometric detection using carbon paste electrode, has been developed for the separation and determination of five phenolic xenoestrogens in chicken eggs and milk powder samples. Efficient separation of five analytes was performed by pressurized CEC using a mobile phase consisting of 60% v/v ACN and 40% v/v Tris buffer (5 mmol/L, pH 8.0), +6 kV of applied voltage and 7.0 MPa of supplementary pressure. Detection limits of 50, 5, 2, 10 and 20 ng/mL for pentachlorophenol, bisphenol‐A, 2,4‐dichlorophenol, 4‐tert‐octylphenol and 4‐nonylphenol, respectively, were achieved using carbon paste electrode as working electrode and +0.8 V as detection potential. Matrix solid phase dispersion extraction method had been employed during sample preparation procedure, and mean recoveries ranged from 79.2 to 102.6% at different concentrations of phenolic xenoestrogens for spiked egg and milk powder samples were obtained.     

Use of volatile organic solvents in headspace liquid‐phase microextraction by direct cooling of the organic drop using a simple cooling capsule

A low‐cost and simple cooling‐assisted headspace liquid‐phase microextraction device for the extraction and determination of 2,6,6‐trimethyl‐1,3 cyclohexadiene‐1‐carboxaldehyde (safranal) in Saffron samples, using volatile organic solvents, was fabricated and evaluated. The main part of the cooling‐assisted headspace liquid‐phase microextraction system was a cooling capsule, with a Teflon microcup to hold the extracting organic solvent, which is able to directly cool down the extraction phase while the sample matrix is simultaneously heated. Different experimental factors such as type of organic extraction solvent, sample temperature, extraction solvent temperature, and extraction time were optimized. The optimal conditions were obtained as: extraction solvent, methanol (10 μL); extraction temperature, 60°C; extraction solvent temperature, 0°C; and extraction time, 20 min. Good linearity of the calibration curve (R² = 0.995) was obtained in the concentration range of 0.01–50.0 μg/mL. The limit of detection was 0.001 μg/mL. The relative standard deviation for 1.0 μg/mL of safranal was 10.7% (n = 6). The proposed cooling‐assisted headspace liquid‐phase microextraction device was coupled (off‐line) to high‐performance liquid chromatography and used for the determination of safranal in Saffron samples. Reasonable agreement was observed between the results of the cooling‐assisted headspace liquid‐phase microextraction high‐performance liquid chromatography method and those obtained by a validated ultrasound‐assisted solvent extraction procedure.     

Preparation and application of carbon nanotubes/poly(o‐toluidine) composite fibers for the headspace solid‐phase microextraction of benzene,toluene, ethylbenzene,and xylenes

A novel nanocomposite coating of poly(o‐toluidine) and oxidized multiwalled CNTs (MWCNTs, where CNTs is carbon nanotubes) was electrochemically prepared on a stainless‐steel wire. The applicability of the fiber was assessed for the headspace solid‐phase microextraction of benzene, toluene, ethylbenzene, and xylenes in aqueous samples followed by GC with flame ionization detection. In order to obtain an adherent and stable composite coating, several experimental parameters related to the coating process, such as polymerization potential and time, and the concentration of o‐toluidine and oxidized MWCNTs were optimized. The combination of MWCNTs and polymer in a nanocomposite form presents desirable opportunities to produce materials for new applications. The effects of various parameters on the efficiency of the headspace solid‐phase microextraction process, such as desorption temperature and time, extraction temperature and time, and ionic strength were also investigated. At the optimum conditions, LODs were 0.03–0.06 μg/L. The method showed linearity in the range of 0.5–300 μg/L with coefficients of determination >0.99. The intraday and interday RSDs obtained at a 5 μg/L concentration level (n = 5) using a single fiber were 1.2–5.2 and 3.2–7.5%, respectively. The fiber‐to‐fiber RSD (%; n = 3) at 5 μg/L was 6.1–9.2%.     

Resorcinol–formaldehyde xerogel as a micro‐solid‐phase extraction sorbent for the determination of herbicides in aquatic environmental samples

In this study, organic aerogels were synthesized by the sol–gel polycondensation of mixed cresol with formaldehyde in a slightly basic aqueous solution. Carbon aerogels and xerogels are generated by pyrolysis of organic aerogels. The novel sol–gel‐based micro‐solid‐phase extraction sorbent, resorcinol–formaldehyde xerogel, was employed for preconcentration of some selected herbicides. Three herbicides of the aryloxyphenoxypropionate group, clodinafop‐propargyl, haloxyfop‐etotyl, and fenoxaprop‐P‐ethyl, were extracted from aqueous samples by micro‐solid‐phase extraction and subsequently determined by gas chromatography with mass spectrometry. The effect of different parameters influencing the extraction efficiency of these herbicides including sample flow rate, sample volume, and extraction time were investigated and optimized. Under optimum conditions, linear calibration curves in the range of 0.10–500 ng/L with R² > 0.99 were obtained. The relative standard deviation at 50 μg/L concentration level was lower than 10% (n = 5) and detection limits were between 0.05 and 0.20 μg/L. The proposed method was successfully applied to the sampling and extraction of herbicides from Zayanderood and paddy water samples.     

Two polydimethylsiloxane rod extraction methods for the sensitive determination of phenolic compounds in water samples

Simple, precise, and low‐cost methods for the simultaneous determination of phenolic endocrine disrupting compounds such as bisphenol A, trichlorophenol, pentachlorophenol, 4‐nonylphenol, and 4‐octylphenol in water samples were developed. The Direct, in situ derivatization methods are based on polydimethylsiloxane rod extraction followed by liquid desorption and chromatographic analysis by liquid chromatography and diode array detection. Several parameters affecting the extraction and desorption of the phenolic compounds and their acetylated derivates were studied, as well as the chromatographic and detection conditions. For the direct method, determination coefficients (r²) > 0.990 and LODs in the 0.6–2 μg/L range were obtained for all compounds except bisphenol A (9.5 μg/L). With the derivatization‐based method, based on in situ acetylation, lower limits of detection (0.3–0.9 μg/L) were obtained for all the compounds with r² > 0.988 and RSDs in the 2–9% range. The developed methods were applied to the analysis of spiked water samples obtaining recoveries of between 60.2 and 131.7% for the direct method, and of between 76.6 and 108.2% for the derivatization‐based method. The results demonstrate the feasibility of using these two methods for determining bisphenol A, trichlorophenol, pentachlorophenol, 4‐nonylphenol, and 4‐octylphenol in water.     

Determination of bisphenol A, 4‐octylphenol,and 4‐nonylphenol in soft drinks and dairy products by ultrasound‐assisted dispersive liquid–liquid microextraction combined with derivatization and high‐performance liquid chromatography with fluorescence detection

A novel hyphenated method based on ultrasound‐assisted dispersive liquid–liquid microextraction coupled to precolumn derivatization has been established for the simultaneous determination of bisphenol A, 4‐octylphenol, and 4‐nonylphenol by high‐performance liquid chromatography with fluorescence detection. Different parameters that influence microextraction and derivatization have been optimized. The quantitative linear range of analytes is 5.0–400.0 ng/L, and the correlation coefficients are more than 0.9998. Limits of detection for soft drinks and dairy products have been obtained in the range of 0.5–1.2 ng/kg and 0.01–0.04 μg/kg, respectively. Relative standard deviations of intra‐ and inter‐day precision for retention time and peak area are in the range of 0.47–2.31 and 2.76–8.79%, respectively. Accuracy is satisfactory in the range of 81.5–118.7%. Relative standard deviations of repeatability are in the range of 0.35–1.43 and 2.36–4.75% for retention time and peak area, respectively. Enrichment factors for bisphenol A, 4‐octylphenol, and 4‐nonylphenol are 170.5, 240.3, and 283.2, respectively. The results of recovery and matrix effect are in the range of 82.7–114.9 and 92.0–109.0%, respectively. The proposed method has been applied to the determination of bisphenol A, 4‐octylphenol, and 4‐nonylphenol in soft drinks and dairy products with much higher sensitivity than many other methods.     

Ionic‐liquid‐mediated poly(dimethylsiloxane)‐ grafted carbon nanotube fiber prepared by the sol–gel technique for the head space solid‐phase microextraction of methyl tert‐butyl ether using GC

A headspace solid‐phase microextraction method was developed for the preconcentration and extraction of methyl tert‐butyl ether. An ionic‐liquid‐mediated multiwalled carbon nanotube–poly(dimethylsiloxane) hybrid coating, which was prepared by covalent functionalization of multiwalled carbon nanotubes with hydroxyl‐terminated poly(dimethylsiloxane) using the sol–gel technique, was used as solid‐phase microextraction adsorbent. This innovative fiber exhibited a highly porous surface structure, high thermal stability (at least 320°C) and long lifespan (over 210 uses). Potential factors affecting the extraction efficiency were optimized. Under the optimum conditions, the method LOD (S/N = 3) was 0.007 ng/mL and the LOQ (S/N = 10) was 0.03 ng/mL. The calibration curve was linear in the range of 0.03–200 ng/mL. The RSDs for one fiber (repeatability, n = 5) at three different concentrations (0.05, 1, and 150 ng/mL) were 5.1, 4.2, and 4.6% and for the fibers obtained from different batches (reproducibility, n = 3) were 6.5, 5.9, and 6.3%, respectively. The developed method was successfully applied to the determination of methyl tert‐butyl ether in different real water samples on three consecutive days. The relative recoveries for the spiked samples with 0.05, 1, and 150 ng/mL were between 94–104%.     

Development of a fabric phase sorptive extraction with high‐performance liquid chromatography and ultraviolet detection method for the analysis of alkyl phenols in environmental samples

A novel analytical method has been developed and validated for the quantification of alkyl phenols in aqueous and soil samples. Fabric phase sorptive extraction, a new sorptive microextraction technique, has been employed for the preconcentration of some endocrine‐disruptor alkylphenol molecules, namely, 4‐tert‐butylphenol, 4‐sec‐butylphenol, 4‐tert‐amylphenol, and 4‐cumylphenol, followed by high‐performance liquid chromatography with ultraviolet detection. Various parameters influencing the fabric phase sorptive extraction performance, namely, extraction time, eluting solvent, elution time and pH of the sample matrix, were optimized. The chromatographic separation was carried out with a mobile phase of acetonitrile/water (60:40 v/v) at an isocratic flow rate of 1.0 mL/min using a reversed‐phase C₁₈ column at λ_max 225 nm. The calibration curves of target analytes were prepared in the concentration range 5–500 ng/mL with good coefficient of determination values (R² > 0.992). Extraction efficiency values were 74.0, 75.6, 78.0, and 78.3 for 4‐tert‐butylphenol, 4‐sec‐butylphenol, 4‐tert‐amylphenol, and 4‐cumylphenol, respectively. The limits of detection range from 0.161 to 0.192 ng/mL. Subsequently, the new fabric phase sorptive extraction with high‐performance liquid chromatography and ultraviolet detection was successfully applied for the recovery of alkyl phenols from spiked ground water, river water, and treated water from a sewage treatment plant, and soil and sludge samples.     

Solid‐phase microextraction based on polyaniline doped with perfluorooctanesulfonic acid coupled to HPLC for the quantitative determination of chlorophenols in water samples

A porous and highly efficient polyaniline‐based solid‐phase microextraction (SPME) coating was successfully prepared by the electrochemical deposition method. A method based on headspace SPME followed by HPLC was established to rapidly determine trace chlorophenols in water samples. Influential parameters for the SPME, including extraction mode, extraction temperature and time, pH and ionic strength procedures, were investigated intensively. Under the optimized conditions, the proposed method was linear in the range of 0.5–200 μg/L for 4‐chlorophenol and 2,4,6‐trichlorophenol, 0.2–200 μg/L for 2,4‐dichlorophenol and 2–200 μg/L for 2,3,4,6‐tetrachlorophenol and pentachlorophenol, with satisfactory correlation coefficients (>0.99). RSDs were <15% (n = 5) and LODs were relatively low (0.10–0.50 μg/L). Compared to commercial 85 μm polyacrylate and 60 μm polydimethylsiloxane/divinylbenzene fibers, the homemade polyaniline fiber showed a higher extraction efficiency. The proposed method has been successfully applied to the determination of chlorophenols in water samples with satisfactory recoveries.     

Metal Oxide Assisted Preparation of Core–Shell Beads with Dense Metal–Organic Framework Coatings for the Enhanced Extraction of Organic Pollutants

Dense and homogeneous metal–organic framework (MOF) coatings on functional bead surfaces are easily prepared by using intermediate sacrificial metal oxide coatings containing the metal precursor of the MOF. Polystyrene (PS) beads are coated with a ZnO layer to give ZnO@PS core–shell beads. The ZnO@PS beads are reactive in the presence of 2‐methylimidazole to transform part of the ZnO coating into a porous zeolitic imidazolate framework‐8 (ZIF‐8) external shell positioned above the internal ZnO precursor shell. The obtained ZIF‐8@ZnO@PS beads can be easily packed in column format for flow‐through applications, such as the solid‐phase extraction of trace priority‐listed environmental pollutants. The prepared material shows an excellent permeance to flow when packed as a column to give high enrichment factors, facile regeneration, and excellent reusability for the extraction of the pollutant bisphenol A. It also shows an outstanding performance for the simultaneous enrichment of mixtures of endocrine disrupting chemicals (bisphenol A, 4‐tert‐octylphenol and 4‐n‐nonylphenol), facilitating their analysis when present at very low levels (<1 μg L^?1) in drinking waters. For the extraction of the pollutant bisphenol A, the prepared ZIF‐8@ZnO@PS beads also show a superior extraction and preconcentration capacity to that of the PS beads used as precursors and the composite materials obtained by the direct growth of ZIF‐8 on the surface of the PS beads in the absence of metal oxide intermediate coatings.     

Effect of sample matrix on sensitivity of mercury and methylmercury quantitation in human urine,saliva, and serum using GC‐MS

A rapid and sensitive method has been developed for the simultaneous determination of monomethylmercury (MMHg) and inorganic mercury (iHg) in human body fluids. The procedure is based on in situ derivatization of MMHg and iHg with sodium tetraethylborate (NaBEt₄) directly in aqueous solutions followed by headspace solid phase microextraction (HS‐SPME). The extracted species from spiked human urine, saliva, and serum are separated by capillary gas chromatography and detected by quadrupole MS (GC‐MS). The optimization of the HS‐SPME conditions like temperature, sample volume, extraction duration, and amount of alkylation agent, was performed in urinary solutions and aqueous solutions similarly buffered. The gas chromatographic conditions like injection temperature, helium flow rate, temperature program, and pressure conditions were also optimized. The recovery was ranged between 85 and 96% for MMHg and 88 and 98% for iHg. The LODs achieved were 10 and 15 ng/L for iHg and MMHg in urine, respectively, 54 and 60 ng/L for iHg and MMHg in saliva, respectively, and 61 and 81 ng/L for iHg and MMHg in serum, respectively. The RSD was ranged between 6.2 and 9.2% for MMHg and 5.0 and 8.2% for iHg.     

Determination of Trace Methyl Tert‐Butyl Ether in Water Samples Using Dispersive Liquid‐Liquid Microextraction Coupled with GC‐FID

A rapid and sensitive analytical method has been developed for trace analysis of methyl tert‐butyl ether (MTBE) in water samples using dispersive liquid‐liquid microextraction and gas chromatography with flame ionization detection. Factors relevant to the microextraction efficiency, such as the kind of extraction solvent, the disperser solvent and their volumes, the effect of salt, sample solution temperature and the extraction time were investigated and optimized. Under the optimal conditions the linear dynamic range of MTBE was from 0.2 to 25.0 μg L^?1 with a correlation coefficient of 0.9981 and a detection limit of 0.1 μg L^?1. The relative standard deviation (RSD%) was less than 5.1% (n = 3) and the recovery values were in the range of 97.8 ± 0.9%. Finally, the proposed method was successfully applied for the analysis of MTBE in aqueous samples.     

Metal–organic framework UiO‐67‐coated fiber for the solid‐phase microextraction of nitrobenzene compounds from water

A sol–gel coating technique was applied for the preparation of a solid‐phase microextraction fiber by coating the metal–organic framework UiO‐67 onto a stainless‐steel wire. The prepared fiber was explored for the headspace solid‐phase microextraction of five nitrobenzene compounds from water samples before gas chromatography with mass spectrometric detection. The effects of the extraction temperature, extraction time, sample solution volume, salt addition, and desorption conditions on the extraction efficiency were optimized. Under the optimal conditions, the linearity was observed in the range of 0.015–12.0 μg/L for the compounds in water samples, with the correlation coefficients (r) of 0.9945–0.9987. The limits of detection of the method were 5.0–10.0 ng/L, and the recoveries of the analytes from spiked water samples for the method were in the range of 74.0–102.0%. The precision for the measurements, expressed as the relative standard deviation, was less than 11.9%.     

Preconcentration Ultra Trace of Cd(II) in Water Samples Using Dispersive Liquid‐Liquid Microextraction with Salen(N,N′‐Bis(Salicylidene)‐Ethylenediamine) and Determination Graphite Furnace Atomic Absorption Spectrometry

Dispersive liquid–liquid microextraction (DLLME) technique was successfully used as a sample preparation method for graphite furnace atomic absorption spectrometry (GF AAS). In this extraction method, 500 μL methanol (disperser solvent) containing 34 μL carbon tetrachloride (extraction solvent) and 0.00010 g Salen(N,N′‐bis(salicylidene)ethylenediamine) (chelating agent) was rapidly injected by syringe into the water sample containing cadmium ions (interest analyte). Thereby, a cloudy solution formed. The cloudy state resulted from the formation of fine droplets of carbon tetrachloride, which have been dispersed, in bulk aqueous sample. At this stage, cadmium reacts with Salen(N,N′‐bis(salicylidene)‐ethylenediamine), and therefore, hydrophobic complex forms which is extracted into the fine droplets of carbon tetrachloride. After centrifugation (2 min at 5000 rpm), these droplets were sedimented at the bottom of the conical test tube (25 ± 1 μL). Then a 20 μL of sedimented phase containing enriched analyte was determined by GF AAS. Some effective parameters on extraction and complex formation, such as extraction and disperser solvent type and their volume, extraction time, salt effect, pH and concentration of the chelating agent have been optimized. Under the optimum conditions, the enrichment factor 122 was obtained from only 5.00 mL of water sample. The calibration graph was linear in the range of 2‐21 ng L^?1 with a detection limit of 0.5 ng L^?1. The relative standard deviation (R.S.D._s) for ten replicate measurements of 20 ng L^?1 of cadmium was 2.9%. The relative recoveries of cadmium in tap, sea and rain water samples at a spiking level of 5 and 10 ng L^?1 are 99, 94, 97 and 96%, respectively. The characteristics of the proposed method have been compared with cloud point extraction (CPE), on‐line liquid‐liquid extraction, single drop microextraction (SDME), on‐line solid phase extraction (SPE) and co‐precipitation based on bibliographic data. Therefore, DLLME combined with GF AAS is a very simple, rapid and sensitive method, which requires low volume of sample (5.00 mL).     

Analysis of semi-volatile organic compounds in aqueous samples by microwave-assisted headspace solid-phase microextraction coupled with gas chromatography-electron capture detection

The pretreatment technique of microwave-assisted headspace solid-phase microextraction (MA-HS-SPME) has been developed and studied for the extraction of semi-volatile organic compounds (SVOCs) in aqueous samples prior to chromatographic analysis. The optimum conditions for obtaining extraction efficiency, such as the extraction time, extraction temperature, addition of salts, and the ratio of sample to headspace volume parameters were investigated. Experimental results indicated that the proposed MA-HS-SPME technique attained the best extraction efficiency under the optimized conditions, i.e., irradiation of extraction solution (20mL aqueous sample in 40mL headspace vial with no addition of salt) under 30W microwave power for 30min at 70 degrees C. The detection was linear at 1-250ng/L with correlation coefficient exceeding 0.997. The detection limits obtained were between 0.2-10.7ng/L, repeatability range from 2 to 15%. Real water samples collected from known sites in southern Taiwan were analyzed using the optimized conditions.     

Ionic‐liquid‐assisted microwave distillation coupled with headspace single‐drop microextraction followed by GC–MS for the rapid analysis of essential oil in Dryopteris fragrans

A rapid, green and effective miniaturized sample preparation technique, ionic‐liquid‐assisted microwave distillation coupled with headspace single‐drop microextraction was developed for the extraction of essential oil from dried Dryopteris fragrans. 1‐Ethyl‐3‐methylimidazolium acetate was the optimal ionic liquid as the destruction agent of plant cell walls and microwave absorption was medium. n‐Heptadecane (2.0 μL) was adopted as the suspended microdrop solvent in the headspace for the extraction and concentration of essential oil. The optimal parameters of the proposed method were an irradiation power of 300 W, sample mass of 0.9 g, mass ratio of ionic liquids to sample of 2.8, extraction temperature of 79°C, and extraction time of 3.6 min. In comparison to the previous reports, the proposed technique could equally monitor all the essential oil components with no significant differences in a simple way, which was more rapid and required a much lower amount of sample.