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1.
    
A selective and sensitive method was developed based on dispersive micro‐solid‐phase extraction for the extraction of hydroquinone, resorcinol, pyrocatechol and phenol from water samples prior to high‐performance liquid chromatography with UV detection. SiO2, SiO2@MPTES, and SiO2@MPTES@Au nanoparticles (MPTES = 3‐mercaptopropyltriethoxysilane) were synthesized and characterized by scanning electronic microscopy, thermogravimetric analysis, differential thermogravimetric analysis, and infrared spectroscopy. Variables such as the amount of sorbent (mg), pH and ionic strength of sample the solution, the volume of eluent solvent (μL), vortex and ultrasonic times (min) were investigated by Plackett–Burman design. The significant variables optimized by a Box–Behnken design were combined by a desirability function. Under optimized conditions, the calibration graphs of phenol and dihydroxybenzenes were linear in a concentration range of 1–500 μg/L, and with correlation coefficients more than 0.995. The limits of detection for hydroquinone, resorcinol, pyrocatechol, and phenol were 0.54, 0.58, 0.46, and 1.24 μg/L, and the limits of quantification were 1.81, 1.93, 1.54, and 4.23 μg/L, respectively. This procedure was successfully employed to determine target analytes in spiked water samples; the relative mean recoveries ranged from 93.5 to 98.9%.  相似文献   

2.
    
A rapid and simple method for the extraction and preconcentration of ceftazidime in aqueous samples has been developed using dispersive liquid–liquid microextraction followed by high‐performance liquid chromatography analysis. The extraction parameters, such as the volume of extraction solvent and disperser solvent, salt effect, sample volume, centrifuge rate, centrifuge time, extraction time, and temperature in the dispersive liquid–liquid microextraction process, were studied and optimized with the experimental design methods. Firstly, for the preliminary screening of the parameters the taguchi design was used and then, the fractional factorial design was used for significant factors optimization. At the optimum conditions, the calibration curves for ceftazidime indicated good linearity over the range of 0.001–10 μg/mL with correlation coefficients higher than the 0.98, and the limits of detection were 0.13 and 0.17 ng/mL, for water and urine samples, respectively. The proposed method successfully employed to determine ceftazidime in water and urine samples and good agreement between the experimental data and predictive values has been achieved.  相似文献   

3.
    
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.  相似文献   

4.
    
Sudan Red pollutants have gained more attention in recent years. The present study described a simple and sensitive determination method for Sudan Red pollutants with dispersive liquid–liquid microextraction coupled to high‐performance liquid chromatography. Chlorobenzene and ethanol were used as the extraction solvent and disperser solvent, respectively. The possible parameters such as the kind of solvents, ionic strength, and sample pH that could affect the enrichment have been optimized. Under the optimal conditions, the pollutants have been well enriched and the linear ranges of Sudan Red I and II were in the range of 0.3–40 μg/L, and the linear ranges of Sudan Red III and IV were in the range of 1.2–160 μg/L. The detection limits were in the range of 0.18–0.46 μg/L, and the precisions were in the range of 3.7–5.9%. All these demonstrated that the proposed method could be a good alternative for the routine analysis of Sudan Red pollutants in water samples.  相似文献   

5.
    
A simple technique for the collection of an extraction solvent lighter than water after dispersive liquid–liquid microextraction combined with high‐performance liquid chromatography with ultraviolet detection was developed for the determination of four paraben preservatives in aqueous samples. After the extraction procedure, low‐density organic solvent together with some little aqueous phase was separated by using a disposable glass Pasteur pipette. Next, the flow of the aqueous phase was stopped by successive dipping the capillary tip of the pipette into anhydrous Na2SO4. The upper organic layer was then removed simply with a microsyringe and injected into the high‐performance liquid chromatography system. Experimental parameters that affect the extraction efficiency were investigated and optimized. Under optimal extraction conditions, the extraction recoveries ranged from 25 to 86%. Good linearity with coefficients with the square of correlation coefficients ranging from 0.9984 to 0.9998 was observed in the concentration range of 0.001–0.5 μg/mL. The relative standard deviations ranged from 4.1 to 9.3% (n = 5) for all compounds. The limits of detection ranged from 0.021 to 0.046 ng/mL. The method was successfully applied for the determination of parabens in tap water and fruit juice samples and good recoveries (61–108%) were achieved for spiked samples.  相似文献   

6.
    
Chagas disease constitutes a major public health problem in Latin America. Human breast milk is a biological sample of great importance for the analysis of therapeutic drugs, as unwanted exposure through breast milk could result in pharmacological effects in the nursing infant. Thus, the goal of breast milk drug analysis is to inquire to which extent a neonate may be exposed to a drug during lactation. In this work, we developed an analytical technique to quantify benznidazole and nifurtimox (the two antichagasic drugs currently available for medical treatment) in human breast milk, with a simple sample pretreatment followed by an ionic‐liquid‐based dispersive liquid–liquid microextraction combined with high‐performance liquid chromatography and UV detection. For this technique, the ionic liquid 1‐octyl‐3‐methylimidazolium hexafluorophosphate has been used as the “extraction solvent.” A central composite design was used to find the optimum values for the significant variables affecting the extraction process: volume of ionic liquid, volume of dispersant solvent, ionic strength, and pH. At the optimum working conditions, the average recoveries were 77.5 and 89.7%, the limits of detection were 0.06 and 0.09 μg/mL and the interday reproducibilities were 6.25 and 5.77% for benznidazole and nifurtimox, respectively. The proposed methodology can be considered sensitive, simple, robust, accurate, and green.  相似文献   

7.
    
A simple, rapid, and efficient method, vortex‐assisted extraction followed by dispersive liquid–liquid microextraction (DLLME) has been developed for the extraction of polycyclic aromatic hydrocarbons (PAHs) in sediment samples prior to analysis by high performance liquid chromatography fluorescence detection. Acetonitrile was used as collecting solvent for the extraction of PAHs from sediment by vortex‐assisted extraction. In DLLME, PAHs were rapidly transferred from acetonitrile to dichloromethane. Under the optimum conditions, the method yields a linear calibration curve in the concentration range from 10 to 2100 ng g?1 for fluorene, anthracene, chrysene, benzo[k]fluoranthene, and benzo[a]pyrene, and 20 to 2100 ng g?1 for other target analytes. Coefficients of determinations ranged from 0.9986 to 0.9994. The limits of detection, based on signal‐to‐noise ratio of three, ranged from 2.3 to 6.8 ng g?1. Reproducibility and recoveries was assessed by extracting a series of six independent sediment samples, which were spiked with different concentration levels. Finally, the proposed method was successfully applied in analyses of real nature sediment samples. The proposed method extended and improved the application of DLLME to solid samples, which greatly shorten the extraction time and simplified the extraction process.  相似文献   

8.
    
A simple, rapid, organic‐solvent‐ and sample‐saving pretreatment technique, called dispersive liquid–liquid microextraction, was developed for the determination of six synthetic phenolic antioxidants from edible oils before high‐performance liquid chromatography with diode array detection. The entire procedure was composed of a two‐step microextraction and a centrifugal process and could be finished in about 5 min, only consuming only 25 mg of sample and 1 mL of the organic solvent for each extraction. The influences of several important parameters on the microextraction efficiency were thoroughly investigated. Recovery assays for oil samples were spiked at three concentration levels, 50, 100 and 200 mg/kg, and provided recoveries in the 86.3–102.5% range with a relative standard deviation below 3.5%. The intra‐day and inter‐day precisions for the analysis were less than 3.8%. The proposed method was successfully applied for the determination of synthetic phenolic antioxidants in different oil samples, and satisfactory results were obtained. Thus, the developed method represents a viable alternative for the quality control of synthetic phenolic antioxidant concentrations in edible oils.  相似文献   

9.
    
The aim of this work is to develop a simple phase‐transfer method for dispersive liquid–liquid microextraction. For this purpose, a polystyrene nanofiber was prepared by a facile electrospinning strategy and used for the first time as an adsorbent to transfer the organic phase in dispersive liquid–liquid microextraction procedure. The fiber was characterized and its chemical stability and excellent hydrophobicity enable it to selectively adsorb the organic solvent in an aqueous sample. High porosity and specific surface area provide a large adsorption capacity. Under the optimal conditions, the developed dispersive liquid–liquid microextraction with high‐performance liquid chromatography method was successfully applied to the analysis of aldehydes in environmental water samples. The merits of this approach are that it is easy‐to‐operate, low‐cost, time‐saving, and has satisfactory sensitivity. It provides an alternative way for fast and convenient phase transfer of the hydrophobic organic solvent from the aqueous phase.  相似文献   

10.
    
A new pretreatment method, SPE combined with dispersive liquid–liquid microextraction, was proposed for the determination of abamectin in citrus fruit samples for the first time. In this method, fruit samples were extracted by ultrasound‐assisted extraction followed by SPE. Then, the SPE was used as a disperser solvent in the next dispersive liquid–liquid microextraction step for further purification and enrichment of abamectin. The effects of various parameters on the extraction efficiency of the proposed method were investigated and optimized. Good linearity of abamectin was obtained from 0.005 to 10.0 mg/kg for B1a and from 0.05 to 10.0 mg/kg for B1b with correlation coefficient (r2) of 0.998 for B1a and 0.991 for B1b, respectively. The LODs were 0.001 and 0.008 mg/kg (S/N = 3) for B1a and B1b, respectively. The relative recoveries at three spiked levels were ranged from 87 to 96% with the RSD less than 11% (n = 3). The method has been successfully applied to the determination of abamectin in citrus fruit samples.  相似文献   

11.
    
A method for the rapid pretreatment and determination of bisphenol A in water samples based on vortex‐assisted liquid–liquid microextraction followed by high‐performance liquid chromatography with fluorescence detection was proposed in this paper. A simple apparatus consisting of a test tube and a cut‐glass dropper was designed and applied to collect the floating extraction drop in liquid–liquid microextraction when low‐density organic solvent was used as the extraction solvent. Solidification and melting steps that were tedious but necessary once the low‐density organic solvent used as extraction solvent could be avoided by using this apparatus. Bisphenol A was selected as model pollutant and vortex‐assisted liquid–liquid microextraction was employed to investigate the usefulness of the apparatus. High‐performance liquid chromatography with fluorescence detection was selected as the analytical tool for the detection of bisphenol A. The linear dynamic range was from 0.10 to 100 μg/L for bisphenol A, with good squared regression coefficient (r2 = 0.9990). The relative standard deviation (n = 7) was 4.7% and the limit of detection was 0.02 μg/L. The proposed method had been applied to the determination of bisphenol A in natural water samples and was shown to be economical, fast, and convenient.  相似文献   

12.
    
A dispersive liquid–liquid microextraction (DLLME) method combined with solvolysis reaction for extraction of the carbamate fungicide benomyl as carbendazim from water samples is described. The method is based on the extraction of benomyl from acidified sample solution and its conversion into carbendazim via solvolysis reaction with DMF as organic solvent. The proposed DLLME method was followed by HPLC with fluorimetric detection for determination of benomyl. The proposed method has good linearity (0.998) with wide linear dynamic range (0.01–25 mg/L) and low detection limit (0.0033 mg/L), making it suitable for benomyl determination in water samples.  相似文献   

13.
    
An easy, quick, and green method, microwave‐assisted liquid–liquid microextraction based on solidification of ionic liquid, was first developed and applied to the extraction of sulfonamides in environmental water samples. 1‐Ethy‐3‐methylimidazolium hexafluorophosphate, which is a solid‐state ionic liquid at room temperature, was used as extraction solvent in the present method. After microwave irradiation for 90 s, the solid‐state ionic liquid was melted into liquid phase and used to finish the extraction of the analytes. The ionic liquid and sample matrix can be separated by freezing and centrifuging. Several experimental parameters, including amount of extraction solvent, microwave power and irradiation time, pH of sample solution, and ionic strength, were investigated and optimized. Under the optimum experimental conditions, good linearity was observed in the range of 2.00–400.00 μg/L with the correlation coefficients ranging from 0.9995 to 0.9999. The limits of detection for sulfathiazole, sulfachlorpyridazine, sulfamethoxazole, and sulfaphenazole were 0.39, 0.33, 0.62, and 0.85 μg/L, respectively. When the present method was applied to the analysis of environmental water samples, the recoveries of the analytes ranged from 75.09 to 115.78% and relative standard deviations were lower than 11.89%.  相似文献   

14.
    
We describe an optimization approach to determine simultaneously occurring chelating agents (glycine, malonic acid, citric acid, glycolic acid, lactic acid, DL‐malic acid, and ethylenediaminetetraacetic acid) in an electroplating effluent using high‐performance liquid chromatography. With chromatography signal area and overall resolution considered as responses, detection conditions were optimized via multiple functions combined with response surface methodology and Plackett–Burman design. Optimized detection conditions were as follows: 15 mmol/L ammonium phosphate buffer (pH 2.5), a 94:6 v/v ratio of ammonium phosphate buffer/acetonitrile, a column temperature of 23.3°C, and a mobile phase flow rate of 1 mL/min. The experimental values conformed to the predicted values and were repeatable (relative standard deviation < 6.4%) and linear (r2 > 0.991) over concentration ranges of 1–100 µmol/L. Moreover, the quantification limit (signal‐to‐noise ratio = 10) and the detection limit (signal‐to‐noise ratio = 3) ranged from 0.03 to 0.15 µmol/L and from 0.01 to 0.04 µmol/L, respectively. These results indicate that high‐performance liquid chromatography coupled with statistical design may be a simple and rapid method for simultaneously determining multiple chelating agents in electroplating wastewater effectively.  相似文献   

15.
    
A rapid, selective and sensitive sample preparation method based on solid‐phase extraction combined with the dispersive liquid–liquid microextration was developed for the determination of pyrethroid pesticides in wheat and maize samples. Initially, the samples were extracted with acetonitrile and water solution followed phase separation with the salt addition. The following sample preparation involves a solid‐phase extraction and dispersive liquid–liquid microextraction step, which effectively provide cleanup and enrichment effects. The main experimental factors affecting the performance both of solid‐phase extraction and dispersive liquid–liquid microextration were investigated. The validation results indicated the suitability of the proposed method for routine analyze of pyrethroid pesticides in wheat and maize samples. The fortified recoveries at three levels ranged between 76.4 and 109.8% with relative standard deviations of less than 10.7%. The limit of quantification of the proposed method was below 0.0125 mg/kg for the pyrethoroid pesticides. The proposed method was successfully used for the rapid determination of pyrethroid residues in real wheat and maize samples from crop field in Beijing, China.  相似文献   

16.
    
Solid‐phase extraction coupled with dispersive liquid–liquid microextraction was developed as an ultra‐preconcentration method for the determination of four organophosphorus pesticides (isocarbophos, parathion‐methyl, triazophos and fenitrothion) in water samples. The analytes considered in this study were rapidly extracted and concentrated from large volumes of aqueous solutions (100 mL) by solid‐phase extraction coupled with dispersive liquid–liquid microextraction and then analyzed using high performance liquid chromatography. Experimental variables including type and volume of elution solvent, volume and flow rate of sample solution, salt concentration, type and volume of extraction solvent and sample solution pH were investigated for the solid‐phase extraction coupled with dispersive liquid–liquid microextraction with these analytes, and the best results were obtained using methanol as eluent and ethylene chloride as extraction solvent. Under the optimal conditions, an exhaustive extraction for four analytes (recoveries >86.9%) and high enrichment factors were attained. The limits of detection were between 0.021 and 0.15 μg/L. The relative standard deviations for 0.5 μg/L of the pesticides in water were in the range of 1.9–6.8% (n = 5). The proposed strategy offered the advantages of simple operation, high enrichment factor and sensitivity and was successfully applied to the determination of four organophosphorus pesticides in water samples.  相似文献   

17.
    
A novel, simple, and rapid method is presented for the analysis of aflatoxin B1, aflatoxin B2, and ochratoxin A in rice samples by dispersive liquid–liquid microextraction combined with LC and fluorescence detection. After extraction of the rice samples with a mixture of acetonitrile/water/acetic acid, mycotoxins were rapidly partitioned into a small volume of organic solvent (chloroform) by dispersive liquid–liquid microextraction. The three mycotoxins were simultaneously determined by LC with fluorescence detection after precolumn derivatization for aflatoxin B1 and B2. Parameters affecting both extraction and dispersive liquid–liquid microextraction procedures, including the extraction solvent, the type and volume of extractant, the volume of dispersive solvent, the addition of salt, the pH and the extraction time, were optimized. The optimized protocol provided an enrichment factor of approximately 1.25 and with detection of limits (0.06–0.5 μg/kg) below the maximum levels imposed by current regulations for aflatoxins and ochratoxin A. The mean recovery of three mycotoxins ranged from 82.9–112%, with a RSD less than 7.9% in all cases. The method was successfully applied to measure mycotoxins in commercial rice samples collected from local supermarkets in China.  相似文献   

18.
    
Optimization of alcoholic‐assisted dispersive liquid–liquid microextraction of pentachlorophenol (PCP) and determination of it with high‐performance liquid chromatography (UV‐Vis detection) was investigated. A Plackett‐Burman design and a central composite design were applied to evaluate the alcoholic‐assisted dispersive liquid–liquid microextraction procedure. The effect of seven parameters on extraction efficiency was investigated. The factor studied were type and volume of extraction and dispersive solvents, amount of salt, and agitation time. According to Plackett‐Burman design results, the effective parameters were type and volume of extraction solvent and agitation time. Next, a central composite design was applied to obtain optimal condition. The optimized conditions were obtained at 170‐μL 1‐octanol and 5‐min agitation time. The enrichment factor of PCP was 242 with limits of detection of 0.04 μg L?1. The linearity was 0.1–100 μg L?1 and the extraction recovery was 92.7%. RSD for intra and inter day of extraction of PCP were 4.2% and 7.8%, respectively for five measurements. The developed method was successfully applied for the determination of PCP in environmental water samples.  相似文献   

19.
    
In this work, mesoporous silica (SBA‐15‐NH2) was used as an efficient adsorbent for extraction of chlordiazepoxide from different samples based on dispersive nanomaterial‐ultrasound assisted microextraction followed by high‐performance liquid chromatography. The prepared sorbent was characterized by fourier transform infrared spectroscopy, scanning electron microscopy, low‐angle X‐ray diffraction, thermal analysis, and N2 adsorption‐desorption surface area measurement. Several variables affecting the extraction efficiency of the chlordiazepoxide, including the amounts of adsorbent, time of adsorption, pH and volume of desorption solvent were optimized by central composite design combined with desirability function. The values of variables were set as 10 mg of SBA‐15‐NH2, 15 min adsorption time, pH = 7.3 and 1 mL methanol. The linear response (0.998) was obtained in the range of 0.006–10 µgmL?1 with detection limit 0.0014 µg/mL and extraction recovery was in the range of 91–96% with relative standard deviation < 6%.  相似文献   

20.
    
Matrix solid‐phase dispersion combined with dispersive liquid–liquid microextraction has been developed as a new sample pretreatment method for the determination of four sulfonylurea herbicides (chlorsulfuron, bensulfuron‐methyl, chlorimuron‐ethyl, and pyrazosulfuron) in tea by high‐performance liquid chromatography with diode array detection. The extraction and cleanup by matrix solid‐phase dispersion was carried out by using CN‐silica as dispersant and carbon nanotubes as cleanup sorbent eluted with acidified dichloromethane. The eluent of matrix solid‐phase dispersion was evaporated and redissolved in 0.5 mL methanol, and used as the dispersive solvent of the following dispersive liquid–liquid microextraction procedure for further purification and enrichment of the target analytes before high‐performance liquid chromatography analysis. Under the optimum conditions, the method yielded a linear calibration curve in the concentration range from 5.0 to 10 000 ng/g for target analytes with a correlation coefficients (r2) ranging from 0.9959 to 0.9998. The limits of detection for the analytes were in the range of 1.31–2.81 ng/g. Recoveries of the four sulfonylurea herbicides at two fortification levels were between 72.8 and 110.6% with relative standard deviations lower than 6.95%. The method was successfully applied to the analysis of four sulfonylurea herbicides in several tea samples.  相似文献   

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