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1.
Unsymmetrical ureas and S‐thiocarbamates were prepared in good to excellent yields by direct condensation of phenylurea with amines and thiols in 1‐butyl‐3‐methylimidazolium tetrafluoroborate ([BMIM]BF4) without the addition of any additives. The [BMIM]BF4 ionic liquid is a mild medium and can be recycled and reused several times.  相似文献   

2.
A simple, rapid and environment‐friendly technique of single‐drop liquid‐phase microextraction has been developed for the determination of sulfonamides in environmental water. Several important parameters including stirring rate, extraction solvent, extraction pH, salinity and extraction time were optimized to maximize the extract efficiency. Extraction solvent 1‐octyl‐3‐methylimidazolium hexafluorophosphate [C8MIM][PF6] ionic liquid showed better extraction efficiency than 1‐butyl‐3‐methylimidazolium hexafluorophosphate [C4MIM][PF6] and 1‐octanol. The optimum experimental conditions were: pH, 4.5; sodium chloride content, 36% w/v; extraction time, 20 min. This method provided low detection limits (0.5–1 ng/mL), good repeatability (the RSD ranging from 4.2 to 9.9%, n=5) and wide linear range (1–1500 ng/mL), with determination coefficients (r2) higher than 0.9989 for all the target compounds. Real sample analysis showed relative recoveries between 63.5 and 115.8% for all the target compounds.  相似文献   

3.
An ionic liquid‐based ultrasound‐assisted extraction method has been developed for the effective extraction of fangchinoline and tetrandrine from Stephaniae tetrandrae. The effects of some ultrasound‐assisted extraction parameters including the concentration of [BMIM][BF4], pH, ultrasonic power and time were investigated to optimize the ultrasound‐assisted extraction conditions. Compared to the regular ultrasound‐assisted extraction and traditional refluent extraction, the proposed [BMIM][BF4]‐based ultrasound‐assisted extraction offered shorter extraction times (from 6 h to 40 min) and remarkable higher efficiencies (approximately 30% improved), which supported the suitability of the proposed approach. In addition, the proposed approach was confirmed by the good correlation coefficient (R2), recovery and reproducibility (RSD, n = 5), which were in the range of 0.9992–0.9995, 85.5–101.1%, and 1.87–4.33%, respectively.  相似文献   

4.
Multi‐walled carbon nanotubes (MWNTs) were dispersed in the ionic liquid [BMIM][BF4] to form a uniform black suspension. Based on it, a novel glucose oxidase (GOx)‐hyaluronic (HA)‐[BMIM][BF4]‐MWNTs/GCE modified electrode was fabricated. UV‐vis spectroscopy confirmed that GOx immobilized in the composite film retained its native structure. The experimental results of EIS indicated MWNTs, [BMIM][BF4] and HA were successfully immobilized on the surface of GCE and [BMIM][BF4]‐MWNTs could obviously improve the diffusion of ferricyanide toward the electrode surface. The experimental results of CV showed that a pair of well‐defined and quasi‐reversible peaks of GOx at the modified electrode was exhibited, and the redox reaction of GOx at the modified electrode was surface‐confined and quasi‐reversible electrochemical process. The average surface coverage of GOx and the apparent Michaelis‐Menten constant were 8.5×10−9 mol/cm2 and 9.8 mmol/L, respectively. The cathodic peak current of GOx and the glucose concentration showed linear relationship in the range from 0.1 to 2.0 mmol/L with a detection limit of 0.03 mmol/L (S/N=3). As a result, the method presented here could be easily extended to immobilize and obtain the direct electrochemistry of other redox enzymes or proteins.  相似文献   

5.
Ionic liquids of 1‐butyl‐3‐methylimidazolium ([BMIM]) cation with different anions (Cl?, Br?, I?, and BF4?), and their aqueous mixtures were investigated by using Raman spectroscopy and dispersion‐included density functional theory (DFT). The characteristic Raman bands at 600 and 624 cm?1 for two isomers of the butyl chain in the imidazolium cation showed significant changes in intensity for different anions as well as in aqueous solutions. The area ratio of these two bands followed the order I?>Br?>Cl?>BF4? (in terms of the anion X in [BMIM]X), indicating that the butyl chain of [BMIM]I tends to adopt the trans conformation. The butyl chain was found to adopt the gauche conformation upon dilution, irrespective of the anion type. The Raman bands in the butyl C?H stretch region for [BMIM]X (X=Cl?, Br?, and I?) blueshifted significantly with the increase in the water concentration, whereas that for [BMIM]BF4 changed very little upon dilution. The blueshift in the C?H stretch region upon dilution also followed the order: [BMIM]I>[BMIM]Br>[BMIM]Cl>[BMIM]BF4, the same order as the above trans conformation preference of the butyl chain in pure imidazolium ionic liquids, which suggested that the cation‐anion interaction plays a role in determining the conformation of the chain.  相似文献   

6.
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).  相似文献   

7.
Hydrophilic ionic liquid of [BMIM][BF4] was successfully applied for the ultrasound-assisted extraction (UAE) of hydrophilic chlorogenic acid from Lonicera japonica Thunb. To explore this extraction procedure, the corresponding extraction parameters including the sample size, [BMIM][BF4] concentration, pH, extraction temperature, ultrasonic power and extraction time were investigated. The results revealed that the [BMIM][BF4]-based UAE efficiency of chlorogenic acid was higher than that of the ethanol-based UAE and the traditional refluent ethanol extraction. And the study on the method reliability further confirmed that the [BMIM][BF4]-based UAE is suitable for the effective extraction of chlorogenic acid from honeysuckle.  相似文献   

8.
Yarrowia lipolytica (YLL), Candida rugosa (CRL), and porcine pancreatic lipase (PPL) were employed successfully as catalysts in the enzymatic ring‐opening polymerization (ROP) of ε‐caprolactone in the presence of 1‐ethyl‐3‐methylimidazolium tetrafluoroborate ([EMIM][BF4]), 1‐butyl‐3‐methylimidazolium tetrafluoroborate ([BMIM][BF4]), 1‐butylpyridinium tetrafluoroborate ([BuPy][BF4]), 1‐butylpyridinium trifluoroacetate ([BuPy][CF3COO]), 1‐ethyl‐3‐methylimidazolium nitrate ([EMIM][NO3]) ionic liquids. Poly(ε‐caprolactone)s (PCLs) with molecular weights (Mn) in the range of 300–9000 Da were obtained. 1H‐ and 13C‐NMR analyses on PCLs formed by YLL, CRL, and PPL showed asymmetric telechelic α‐hydroxy‐ω‐carboxylic acid end groups. Differences between CP‐MAS and MAS spectra are observed and discussed in terms of morphology. MALDI‐TOF spectra show the formation of at least seven species. Differential scanning calorimetry (DSC) and Wide Angle X‐Ray Scattering (WAXS) results demonstrate the high degree of crystallinity present in all the polyesters. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5792–5805, 2009  相似文献   

9.
A rapid, sensitive and rugged solid‐phase extraction ultra performance liquid chromatography tandem mass spectrometry (UPLC‐MS/MS) method was developed for determination of paroxetine in human plasma. The procedure for sample preparation includes simple SPE extraction procedure coupled with Hypersil Gold C18 column (100 mm ? 2.1 mm, i.d., 1.9 μm) with isocratic elution at a flow‐rate of 0.350 mL/min and fluoxetine was used as the internal standard. The analysis was performed on a triple‐quadrupole tandem mass spectrometer by multiple reactions monitoring mode via electrospray ionization. Using 500 μL plasma, the methods were validated over the concentration range 0.050–16.710 ng/mL for paroxetine, with a lower limit of quantification of 0.050 ng/mL. The intra‐ and inter‐day precision and accuracy of the quality control samples were within 10.0%. The recovery was 69.2 and 74.4% for paroxetine and fluoxetine respectively. Total run time was only 1.9 min. The method was highly reproducible and gave peaks with excellent chromatography properties. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

10.
An efficient and green procedure for the synthesis of novel 12‐aryl‐8,9,10,12‐tetrahydrobenzo[a]xanthen‐11‐one derivatives has been described through one‐pot condensation of 2‐naphthol, arylaldehyde and 5,5‐dimethyl‐cyclohexane‐1,3‐dione in the presence of sulfamic acid (NH2SO3H) in ionic liquid 1‐n‐butyl‐3‐methylimidazolium tetrafluoroborate ([BMIM]BF4). These reactions proceed with good yields under short reaction time. Furthermore, the green catalytic system can be recycled specific times with no decreases in yields and reaction rates.  相似文献   

11.
A sensitive, simple method for quantification of chloroquine (CQ) and desethylchloroquine (MCQ) in whole blood and plasma from Plasmodium vivax patients has been developed using HPLC with diode array detection (DAD). Solid‐phase extraction on Isolute‐96‐CBA was employed to process 100 μL of plasma/whole blood samples. CQ, MCQ and quinine were separated using a mobile phase of phosphate buffer 25 mm , pH 2.60–acetonitrile (88:12, v/v) with 2 mm sodium perchlorate on a Zorbax SB‐CN 150 × 4.6 mm, 5 μm column at a flow rate of 1.2 mL/min, at ambient temperature in 10 min, with the DAD wavelength of 343 nm. The method was linear over the range of 10–5000 ng/mL for both CQ and MCQ in plasma and whole blood. The limit of detection was 4 ng/mL and limit of quantification was 10 ng/mL in both plasma and blood for CQ and MCQ. The intra‐, inter‐ and total assay precision were <10% for CQ and MCQ in plasma and whole blood. In plasma, the accuracies varied between 101 and 103%, whereas in whole blood, the accuracies ranged from 97.0 to 102% for CQ and MCQ. The method is an ideal technique with simple facilities and instruments, bringing about good separation in comparison with previous methods. © 2016 The Authors Biomedical Chromatography Published by John Wiley & Sons Ltd  相似文献   

12.
The hydrophobic ionic liquid of [BMIM][PF6] was successfully used for the ultrasound‐assisted extraction of hydrophobic magnolol and honokiol from cortex Magnoliae officinalis. To obtain the best extraction efficiencies, some ultrasonic parameters including the concentration of [BMIM][PF6], pH, ultrasonic power and ultrasonic time were evaluated. The results obtained indicated that the [BMIM][PF6]‐based ultrasound‐assisted extraction efficiencies of magnolol and honokiol were greater than those of the [BMIM][BF4]‐based ultrasound‐assisted extraction (from 48.6 to 45.9%) and the traditional ethanol reflux extraction (from 16.2 to 13.3%). Furthermore, the proposed extraction method is validated by the recovery, correlation coefficient (R2) and reproducibility (RSD, n=5), which were 90.8–102.6, 0.9992–0.9998, and 1.6–5.4%, respectively.  相似文献   

13.
First, the direct and indirect electrochemical oxidation of ammonia has been studied by cyclic voltammetry at glassy carbon electrodes in propylene carbonate. In the case of the indirect oxidation of ammonia, its analytical utility of indirect for ammonia sensing was examined in the range from 10 and 100 ppm by measuring the peak current of new wave resulting from reaction between ammonia and hydroquinone, as function of ammonia concentration, giving a sensitivity 1.29×10?7 A ppm?1 (r2=0.999) and limit‐of‐detection 5 ppm ammonia. Further, the direct oxidation of ammonia has been investigated in several room temperature ionic liquids (RTILs), namely 1‐butyl‐3‐methylimidazolium tetrafluoroborate ([C4mim] [BF4]), 1‐butyl‐3‐methylimidazolium trifluoromethylsulfonate ([C4mim] [OTf]), 1‐Ethyl‐3‐methylimidazolium bis(trifluoromethylsulfonyl)imide ([C2mim] [NTf2]), 1‐butyl‐3‐methylimidazolium bis(trifluoromethylsulfonyl)imide ([C4mim] [NTf2]) and 1‐butyl‐3‐methylimidazolium hexafluorophosphate ([C4mim] [PF6]) on a 10 μm diameter Pt microdisk electrode. In four of the RTILs studied, the cyclic voltammetric analysis suggests that ammonia is initially oxidized to nitrogen, N2, and protons, which are transferred to an ammonia molecule, forming NH via the protonation of the anion(s) (A?). However, in [C4mim] [PF6], the protonated anion was formed first, followed by NH . In all five RTILs, both HA and NH are reduced at the electrode surface, forming hydrogen gas, which is then oxidized. The analytical ability of this work has also been explored further, giving a limit‐of‐detection close to 50 ppm in [C2mim] [NTf2], [C4mim] [OTf], [C4mim] [BF4], with a sensitivity of ca. 6×10?7 A ppm?1 (r2=0.999) for all three ionic liquids, showing that the limit of detection was ca. ten times larger than that in propylene carbonate since ammonia in propylene carbonate might be more soluble in comparison with RTILs when considering the higher viscosity of RTILs.  相似文献   

14.
CuO feather‐like and flower‐like crystals have been synthesized by a fast microwave‐assisted solution approach using Cu(NO3)2 and NaOH. The morphology transformation of CuO could be achieved by ionic liquid 1‐n‐butyl‐3‐methyl imidazolium tetrafluoroborate ([BMIM]BF4). With [BMIM]BF4, flower‐like CuO were obtained, whereas without [BMIM]BF4, feather‐like CuO were obtained. The possible formation mechanism of flower‐like CuO was discussed on the basis of experimental results. The products were characterized by XRD, FESEM/EDS, and TEM/SAED. In addition, the adsorption of [BMIM]BF4 on flower‐like CuO was confirmed by FTIR and TG/DSC, and the band gap energies of the flower‐like CuO was estimated by UV‐vis spectra.  相似文献   

15.
In this work, a novel magnetic nanomaterial functionalized with a molecularly imprinted polymer was prepared for the extraction of protoberberine alkaloids. Molecularly imprinted polymers were made on the surface of Fe3O4 nanoparticles by using berberine as template, acetonitrile/water as porogen, acrylamide as functional monomer and ethylene glycol dimethacrylate as cross‐linker. The optimized molar ratio of template/functional monomer was 1:7. The polymeric magnetic nanoparticles were characterized by transmission electron microscopy and Fourier transform infrared spectroscopy. The stability and adsorption capacity of the molecularly imprinted polymers were investigated. The molecularly imprinted polymers were used as a selective sorbent for the magnetic molecularly imprinted solid‐phase extraction and determination of jatrorrhizine, palmatine, and berberine. Extraction parameters were studied including loading pH, sample volume, stirring speed, and extraction time. Finally, a magnetic molecularly imprinted solid‐phase extraction coupled to high‐performance liquid chromatography method was developed. Under the optimized conditions, the method showed good linear range of 0.1–150 ng/mL for berberine and 0.1–100 ng/mL for jatrorrhizine and palmatine. The limit of detection was 0.01 ng/mL for berberine and 0.02 ng/mL for jatrorrhizine and palmatine. The proposed method has been applied to determine protoberberine alkaloids in Cortex phellodendri and rat plasma samples. The recoveries ranged from 87.33–102.43%, with relative standard deviation less than 4.54% in Cortex phellodendri and from 102.22–111.15% with relative standard deviation less than 4.59% in plasma.  相似文献   

16.
A rapid and sensitive high‐performance liquid chromatography and electrospray tandem mass spectrometry method was developed and validated for estimation of fulvestrant in rabbit plasma using liquid–liquid extraction. The separation and quantification of fulvestrant were achieved by reverse‐phase chromatography on a Sunfire C18 column (50 × 2.1. i.d., 3.5 μm) with isocratic elution at a flow rate of 300 μL/min using norethistrone as an internal standard from 500 μL plasma sample. The method was validated over the concentration range from 0.092 to 16.937 ng/mL with a lower limit of detection of 0.023 ng/mL. The intra‐day and inter‐day accuracy and precision were within 10%. The recovery was 85 and 90% for fulvestrant and norethistrone respectively. The chromatographic run time was only 2.5 min. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

17.
A rapid, simple and sensitive ultra high‐performance liquid chromatography (UHPLC‐MS/MS) method was established for determining the absorption amount of emodin in the five digestive segments of rat. Plasma samples were pre‐purified by solid‐phase extraction (SPE) with Oasis MAX cartridge. Separation of emodin and 1,8‐dihydroxyanthraquinone (internal standard) was performed on an Acquity BEH UHPLC C18 column (100 mm×2.1 mm, 1.7 μm) with gradient elution of methanol and 0.1% formic acid aqueous solution. The LC/MS system was operated under multiple reaction monitoring mode using electrospray ionization (ESI) in negative ion mode. The results showed that this established method was valid and sensitive for emodin within 0.04–16.4 μg/mL, with low limits of detection and quantification of 0.6 ng/mL and 2.4 ng/mL, respectively and upper limit of quantification of 220.0 ng/mL. The intra‐ and interday variations were below 4.9% of RSD. The extraction recoveries were 98.9–106.1% with RSD of 1.9–3.2%. The plasma concentration‐time relationship showed that the absorption of emodin in stomach was faster than in intestine segments. The sequence of absorption amount was: ileum>jejunum>colon≈duodenum>stomach. Most of emodin was absorbed in ileum, and the absorption amount was increased with prolonged retention of drug form in intestine, especially in ileum and jejunum. The developed UHPLC‐ESI‐MS/MS method was appropriate for determining the in vivo absorption of emodin in other herbal medicines or preparations containing this compound.  相似文献   

18.
A liquid chromatographic–electrospray ionization–time‐of‐flight/mass spectrometric (LC‐ESI‐TOF/MS) method was developed and applied for the determination of WKYMVm peptide in rat plasma to support preclinical pharmacokinetics studies. The method consisted of micro‐elution solid‐phase extraction (SPE) for sample preparation and LC‐ESI‐TOF/MS in the positive ion mode for analysis. Phenanthroline (10 mg/mL) was added to rat blood immediately for plasma preparation followed by addition of trace amount of 2 m hydrogen chloride to plasma before SPE for stability of WKYMVm peptide. Then sample preparation using micro‐elution SPE was performed with verapamil as an internal standard. A quadratic regression (weighted 1/concentration2), with the equation y = ax2 + bx + c was used to fit calibration curves over the concentration range of 3.02–2200 ng/mL for WKYMVm peptide. The quantification run met the acceptance criteria of ±25% accuracy and precision values. For quality control samples at 15, 165 and 1820 ng/mL from the quantification experiment, the within‐run and the between‐run accuracy ranged from 92.5 to 123.4% with precision values ≤15.1% for WKYMVm peptide from the nominal values. This novel LC‐ESI‐TOF/MS method was successfully applied to evaluate the pharmacokinetics of WKYMVm peptide in rat plasma.  相似文献   

19.
An ionic liquid (IL) in situ preconcentration method was optimized and applied to the monitoring of the 15 + 1 European Union polycyclic aromatic hydrocarbons in water and fruit‐tea infusions. The optimized method utilizes 10 mL of water (or infusion) containing 38 μL of the IL 1‐butyl‐3‐methylimidazolium chloride and a content of 36.1 g/L NaCl, which are mixed with Li‐NTf2 (340 μL, 0.2 g/mL), followed by vortex (4 min) and centrifugation (5 min). The obtained microdroplet containing hydrocarbons is diluted with acetonitrile and injected into an HPLC with UV/Vis and fluorescence detection. The method presented average enrichment factors of 127 for water (tap water and bottled water) and 27 for two fruit‐tea infusions; with average relative recoveries of 86.7 and 106% for water and fruit‐tea infusions, respectively. The method was sensitive, with detection limits ranging from 0.001 to 0.050 ng/mL in water, and from 0.010 to 0.600 ng/mL in fruit‐tea infusions, for the fluorescent hydrocarbons. Real extraction efficiencies ranged from 12.7 to 58.7% for water, and from 20.2 to 117% for the infusions. The method was also fast (~12 min) and free of organic solvents in the extraction step.  相似文献   

20.
A rapid dispersive micro‐solid phase extraction (D‐μ‐SPE) combined with LC/MS/MS method was developed and validated for the determination of ketoconazole and voriconazole in human urine and plasma samples. Synthesized mesoporous silica MCM‐41 was used as sorbent in d ‐μ‐SPE of the azole compounds from biological fluids. Important D‐μ‐SPE parameters, namely type desorption solvent, extraction time, sample pH, salt addition, desorption time, amount of sorbent and sample volume were optimized. Liquid chromatographic separations were carried out on a Zorbax SB‐C18 column (2.1 × 100 mm, 3.5 μm), using a mobile phase of acetonitrile–0.05% formic acid in 5 mm ammonium acetate buffer (70:30, v /v). A triple quadrupole mass spectrometer with positive ionization mode was used for the determination of target analytes. Under the optimized conditions, the calibration curves showed good linearity in the range of 0.1–10,000 μg/L with satisfactory limit of detection (≤0.06 μg/L) and limit of quantitation (≤0.3 μg/L). The proposed method also showed acceptable intra‐ and inter‐day precisions for ketoconazole and voriconazole from urine and human plasma with RSD ≤16.5% and good relative recoveries in the range 84.3–114.8%. The MCM‐41‐D‐μ‐SPE method proved to be rapid and simple and requires a small volume of organic solvent (200 μL); thus it is advantageous for routine drug analysis.  相似文献   

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