Optimized extraction of polycyclic aromatic hydrocarbons from contaminated soil samples

A comparison of Soxhlet extraction and a new extraction technique, fluidized-bed extraction, has been conducted. The extraction of polycyclic aromatic hydrocarbons (PAHs) by this new technique has been optimized considering as experimental variables the variation of the number of extraction cycles and the holding time after reaching the heating temperature by means of a surface response design. The significance of the operational parameters of the fluidized-bed extraction onto the performance characteristics has been investigated. For the determination of the analytes, a cleanup of the extracts followed by gas chromatography with mass spectrometric detection was used. The accuracy of the method was established by extraction and analysis of a reference material, supplied from the European Commission's Joint Research Centre.     

Effect of extraction method on the yield of furanocoumarins from fruits of Archangelica officinalis Hoffm

Optimal conditions for the extraction and analysis of furanocoumarins from fruits of Archangelica officinalis Hoffm. have been determined. The following extraction methods were used: exhaustive extraction in a Soxhlet apparatus, ultrasonication at 25 and 60 degrees C, microwave-assisted solvent extraction in open and closed systems, and accelerated solvent extraction (ASE). In most cases the yields of furanocoumarins were highest using the ASE method. The effects of extracting solvent, temperature and time of extraction using this method were investigated. The highest yield of furanocoumarins by ASE was obtained with methanol at 100-130 degrees C for 10 min. The extraction yields of furanocoumarins from plant material by ultrasonication at 60 degrees C and microwave-assisted solvent extraction in an open system were comparable to the extraction yields obtained in the time- and solvent-consuming exhaustive process involving the Soxhlet apparatus.     

Supercritical fluid extraction of naringin from the peel of Citrus paradisi

The highest yield (14.4 g/kg) of naringin, the major flavonoid from the peel of Citrus paradisi L., that could be achieved by supercritical fluid extraction was obtained using supercritical carbon dioxide modified with 15% ethanol and fresh (rather than dried) peels at 95 bar and 58.6 degrees C. This yield is higher than that attained by the conventional technique of maceration, and close to those obtained by reflux and Soxhlet methods. Furthermore, supercritical fluid extraction consumes less solvent and provides a shorter extraction time than conventional extraction methods.     

Lipid sovent systems are not equivalent for analysis of lipid classes in the microeukaryotic green alga,Chlorella

A comparison of three lipid solvent system indicated that they are not equivalent for the analysis of lipid classes in the green alga, Chlorella. Soxhlet extraction (methylene chloride/methanol, 3 h refulx) recovers more neutral lipid than the other methods but is equivalent to the room-temperature Bligh and Dyer (chloroform/methanol/water) extraction modified with phosphate buffer in glycolipid and polar lipid recovery. The Soxhlet method, however, gave a significantly lower recovery of many polyunsaturated fatty acids. The hexane/isopropanol method is selective for algal neutral lipids with poor recovery of membrane lipids (glyco- and polar lipids). Although this selectivity may have some useful applications, for biochemical studies of lipid synthesis in Chlorella, the modified Bligh and Dyer provides the most quantitative and reproducible recovery of all Chlorella lipid classes while minimizing artifacts due to the extraction procedure.     

Isolation of chlorophylls and carotenoids from freshwater algae using different extraction methods

Usually marine algae are an excellent source of pigments for different commercial sectors. Freshwater macroalgae can be exploited as a good source of biologically active compounds provided an appropriate extraction method is developed. The efficiency of four methods, like microwave‐assisted (MAE), ultrasound‐assisted extraction (UAE), supercritical fluid extraction (SFE) with ethanol as a co‐solvent, as well as conventional Soxhlet extraction were studied in the same conditions (time, solvent and temperature) for the recovery of chlorophylls and carotenoids from three freshwater green algae species: Cladophora glomerata, Cladophora rivularis and Ulva flexuosa. UV‐Vis spectrophotometry was used to determine chlorophyll a, chlorophyll b and total carotenoid content in obtained extracts. The results of this study showed that the advantages of novel extraction techniques (MAE and UAE) include higher yield and, in consequence, lower costs compared to traditional solvent extraction techniques. These methods were much more efficient in freshwater green algae pigment recovery than the classic Soxhlet extraction as well as SFE.     

Influence of the extraction mode on the yield of some furanocoumarins from Pastinaca sativa fruits

Analysis of plant material is an important task in chemotaxonomical investigations, in search of plants with pharmacological activity or in standardisation of plant drugs. The choice of optimal conditions for the analysis of plant material and effect of extraction method on the yield of furanocoumarins from Pastinaca sativa fruits were examined. The following extraction methods were used in experiments: exhaustive extraction in Soxhlet apparatus, ultrasonification (USAE) at 25 and 60 degrees C, microwave-assisted solvent extraction in open and closed system (MASE) and accelerated solvent extraction (ASE). In most cases, the yield of furanocoumarins was highest by use of ASE method as well as by ultrasonification at 60 degrees C.     

Extraction Efficiency and HPLC Determination of Imidacloprid in Soil

Two extraction methods were successfully applied to study the extraction of imidacloprid from soil. The first method, using a mix of acetone and hexane, was based on Soxhlet extraction, and the second method, using acetonitrile, methanol, and water, was a modified version of a liquid extraction method. Quantification was performed by reversed-phase High Performance Liquid Chromatography (HPLC) with Diode Array Detection (DAD) at 270 nm using 40:60 (v/v) acetonitrile/water as a mobile phase. The mean recoveries for imidacloprid from soil ranged from 82.6 to 109%, with a relative standard deviation between 1.9 and 5.6% for both extraction methods. The detector linearity and the reproducibility of the method proved to be very precise. The limits of detection were 0.08 and 0.06 mg kg^?1 for liquid extraction and Soxhlet extraction, respectively. Overall, the efficiency of the Soxhlet extraction at lower concentrations was better than at higher concentrations, while liquid extraction proved efficient for all spiked levels. Liquid extraction performed better at higher concentrations compared to Soxhlet extraction. Taken together, our study suggests that the analysis of imidacloprid in soil can be performed with the modified liquid extraction method with a higher recovery and a lower RSD than Soxhlet extraction.     

A Rapid Screening Method for the Determination of Seventy Pesticide Residues in Soil Using Microwave-Assisted Extraction Coupled to Gas Chromatography and Mass Spectrometry

A rapid screening method using microwave-assisted extraction (MAE) in combination with gas chromatography and mass spectrometry for the determination of 70 pesticide residues in soil was established. The pesticides included 27 organophosphorus pesticides (OPPs), 29 organochlorine pesticides (OCPs), nine pyrethroids, and five carbamates. Parameters that could affect the efficiency of extraction, such as temperature, time, and solvent, were investigated. The condition of the extraction, under which recoveries of all 70 pesticides ranged from 70% to 120%, was optimized with a 1:1 (V/V) mixture of acetone and hexane, a temperature of 100°C, and an extraction time of 10 min. All compounds studied could be recovered in good yields and with relative standard deviations (RSDs) lower than 20%. The linearity of the method for all the pesticides was greater than 0.99 over a concentration range of 0.1–5 μg/g. The detection limits varied from 0.5 to 211.25 ng/g. Interday and intraday precision analyses yielded RSDs of 1.2%–11.7% and 3.6%–15.1%, respectively. This method, which was as effective as Soxhlet extraction and accelerated solvent extraction (ASE), proved to be accurate and precise. When the proposed method was used to examine environmental samples, the obtained results were in good agreement with those obtained using Soxhlet extraction.     

Microwave-assisted extraction of glycyrrhizic acid from licorice root

In the present study, a microwave-assisted extraction (MAE) technique has been developed for the extraction of glycyrrhizic acid (GA) from licorice root. Various experimental conditions, such as extraction time, different ethanol and ammonia concentration, liquid/solid ratios, pre-leaching time before MAE and material size for the MAE procedure were investigated to optimize the efficiency of the extraction. Under appropriate MAE conditions, such as extraction times of 4-5min, ethanol concentrations of 50-60% (v/v), ammonia concentrations of 1-2% (v/v) and liquid/solid ratios of 10:1(ml/g), the recovery of GA from licorice root with MAE was equivalent with conventional extraction methods. Those methods include extraction at room temperature (ERT), the traditional Soxhlet extraction, heat reflux extraction and ultrasonic extraction. Due to the considerable savings in time and solvent, MAE was more effective than the conventional methods. This novel method is suitable for fast extraction of GA from licorice root.     

Techniques of preparing plant material for chromatographic separation and analysis

This paper discusses preparation techniques of samples of plant material for chromatographic analysis. Individual steps of the procedures used in sample preparation, including sample collection from the environment or from tissue cultures, drying, comminution, homogenization, leaching, extraction, distillation and condensation, analyte enrichment, and obtaining the final extracts for chromatographic analysis are discussed. The techniques most often used for isolation of analytes from homogenized plant material, i.e., Soxhlet extraction, ultrasonic solvent extraction (sonication), accelerated solvent extraction, microwave-assisted extraction, supercritical-fluid extraction, steam distillation, as well as membrane processes are emphasized. Sorptive methods of sample enrichment and removal of interferences, i.e., solid-phase extraction, and solid-phase micro-extraction are also discussed.     

Techniques of preparing plant material for chromatographic separation and analysis

This paper discusses preparation techniques of samples of plant material for chromatographic analysis. Individual steps of the procedures used in sample preparation, including sample collection from the environment or from tissue cultures, drying, comminution, homogenization, leaching, extraction, distillation and condensation, analyte enrichment, and obtaining the final extracts for chromatographic analysis are discussed. The techniques most often used for isolation of analytes from homogenized plant material, i.e., Soxhlet extraction, ultrasonic solvent extraction (sonication), accelerated solvent extraction, microwave-assisted extraction, supercritical-fluid extraction, steam distillation, as well as membrane processes are emphasized. Sorptive methods of sample enrichment and removal of interferences, i.e., solid-phase extraction, and solid-phase micro-extraction are also discussed.     

四种真菌油脂提取方法的比较研究

采用索氏法、超临界CO2萃取法、酸热法和有机溶剂法分别提取雅致枝霉、拉曼被孢霉、少根根霉、畸雌腐霉和橙黄红酵母的油脂,从样品要求、最小样品量、仪器要求、处理样品能力及油脂得率等方面对4种提取方法进行综合评价,并对索氏法、超临界CO2萃取法和酸热法提取的雅致枝霉油脂的脂肪酸组成进行气相色谱分析。索氏法的油脂得率最高,但耗时较长;超临界CO2萃取法和酸热法的油脂得率相近,较索氏法略低,但酸热法更为简便,单位时间内样品处理能力强;有机溶剂法提取效果最差。我们建立的酸热法是一种适合油脂及多水饱和脂肪酸高产菌株筛选的简便、有效的真菌油脂提取方法。     

Simultaneous determination of cortisol and prednisolone in body fluids by using HPLC-DAD coupled with second-order calibration based on alternating trilinear decomposition

A novel method for simultaneous determination of cortisol and prednisolone in body fluids has been developed in this paper. Three-way data recorded by high-performance liquid chromatography with a diode array detector (HPLC-DAD) have been analyzed by second-order calibration based on the alternating trilinear decomposition (ATLD) algorithm. The chemometric methodology selected exploits the second-order advantage of the three-way data arrays, which allows one to obtain concentrations of individual calibrated analytes even in the presence of interferences not present in the calibration samples (e.g. background in urine or plasma). It was applied to simultaneous determination of cortisol and prednisolone in both plasma and urine samples. Though the chromatographic and spectral peaks of the analytes were heavily overlapped and interferents coeluted with the compounds studied, good recoveries of the analytes could be obtained with HPLC-DAD coupled with second-order calibration based on ATLD. Sample preparation was based on solvent extraction (SE), and quantification can be carried out with simple mobile phase. The time required for the quantification process is shorter than other methods.     

正交试验法优选烟草中辅酶Q10的匀浆提取工艺

以烟草叶片为原料,用正交试验法优化了烟草中辅酶Q10的匀浆提取工艺,考察了匀浆时间、乙醇体积分数、液料比和提取次数4个因素对辅酶Q10提取率的影响,确立了烟草中辅酶Q10的优化匀浆提取工艺条件为:提取溶剂为85%乙醇,匀浆时间6 min,液料比9∶1(mL/g),提取次数2次。将该法与索氏提取进行了对比。结果表明,匀浆提取烟草中辅酶Q10的提取率为12.82μg·g-1,与索氏提取的提取率相当,但匀浆提取所用提取时间短,提取溶剂用量少,因此匀浆法具有明显的优势。     

Multivariate optimisation of microwave-assisted extraction of capsaicin from Capsicum frutescens L. and quantitative analysis by 1H-NMR

A simple and rapid microwave-assisted extraction (MAE) procedure combined with 1H-NMR spectrometry was developed and optimised for the extraction and quantitative determination of capsaicin in Capsicum frutescens. The influence of experimental variables, including irradiation power, extraction temperature and dynamic extraction time before reaching the selected extraction temperature, on the performance of the extraction procedure was systematically studied using a Box-Behnken experimental design followed by a conventional central composite design approach. Statistical treatment of the results together with results from some additional experiments suggested optimum extraction conditions as 120 degrees C and 150 W, for 15 min with acetone as extractant. The optimised MAE method provides extracts that can be analysed quantitatively using 1H-NMR without any preliminary clean-up or derivatisation steps. In the 1H-NMR spectrum of the crude extracts the doublet signal in the delta range 4.349-4.360 ppm was well separated from other resonances in deuterated chloroform. The quantity of the compound was calculated from the relative ratio of the integral value of the target peak to that of a known amount of dimethylformamide as internal standard. In comparison with traditional Soxhlet extraction, the proposed method is less labour-intensive and provides a drastic reduction of extraction time and solvent consumption. In addition, MAE showed higher extraction yield and selectivity, with comparable reproducibility and recovery, relative to both conventional Soxhlet and sonication methods.     

Preconcentration of pharmaceuticals residues in sediment samples using microwave assisted micellar extraction coupled with solid phase extraction and their determination by HPLC-UV

An analytical method combining microwave assisted micellar extraction (MAME) and solid phase extraction (SPE) has been developed to extract and preconcentrate a selected group of eight pharmaceutical compounds in sediment samples prior to their determination using liquid chromatography with an UV-DAD detector. A non-ionic surfactant, Polyoxyethylene 10 lauryl ether (POLE) was used for the MAME extraction and the different parameters for the optimization process were studied. Then, SPE was used to clean-up and preconcentrate the target analytes in the extract, prior to their determination using HPLC-UV. The method was applied to the determination of the selected pharmaceuticals compounds in several kinds of sediment samples with different characteristics. Relative recoveries for spiked sediment samples were over 70% and relative standard deviations (RSDs) were under 11% for all recoveries tested. Detection limits between 4 and 167ngg(-1) were obtained. The method was validated using Soxhlet extraction procedure.     

Determination of food constituents based on SFE: applications to vitamins A and E in meat and milk

A method has been developed for the determination of vitamins A and E in food using supercritical fluid extraction (SFE), applying liquid or solid trapping, with an accuracy equal to conventional solvent extraction methods. Under optimal conditions, using methanol modified carbon dioxide as a supercritical fluid, Hydromatrix as a water adsorbent, and with a small amount of ascorbic acid and methanol added to the sample, the extraction time is reduced to 80 min. This time is considerably shorter than in conventional methods. Other advantages are the reduction of manual manipulations leading to lower labour costs and reduced consumption of organic solvents in the sample preparation step.     

Optimisation of supercritical fluid extraction of indole alkaloids from Catharanthus roseus using experimental design methodology--comparison with other extraction techniques

Response surface modelling, using MODDE 6 software for Design of Experiments and Optimisation, was applied to optimise supercritical fluid extraction (SFE) conditions for the extraction of indole alkaloids from the dried leaves of Catharanthus roseus. The effects of pressure (200-400 bar), temperature (40-80 degrees C), modifier concentration (2.2-6.6 vol%) and dynamic extraction time (20-60 min) on the yield of alkaloids were evaluated. The extracts were analysed by high-performance liquid chromatography and the analytes were identified using ion trap-electrospray ionisation-mass spectrometry. The method was linear for alkaloid concentration in the range 0.18-31 microg/mL. The limits of detection and quantification for catharanthine, vindoline, vinblastine and vincristine were 0.2, 0.15, 0.1 and 0.08 microg/mL and 2.7, 2.0, 1.3 and 1.1 microg/g, respectively. The dry weight content of major alkaloids in the plants were compared using different extraction methods, i.e. SFE, Soxhlet extraction, solid-liquid extraction with sonication and hot water extraction at various temperatures. The extraction techniques were also compared in terms of reproducibility, selectivity and analyte recoveries. Relative standard deviations for the major alkaloids varied from 4.1 to 17.5% in different extraction methods. The best recoveries (100%) for catharanthine were obtained by SFE at 250 bar and 80 degrees C using 6.6 vol% methanol as modifier for 40 min, for vindoline by Soxhlet extraction using dichloromethane in a reflux for 16 h, and for 3',4'-anhydrovinblastine by solid-liquid extraction using a solution of 0.5 m sulphuric acid and methanol (3:1 v/v) in an ultrasonic bath for 3 h.     

The development and validation of liquid chromatography method for the simultaneous determination of metformin and glipizide, gliclazide, glibenclamide or glimperide in plasma

This article describes the development of SPE and HPLC methods for the simultaneous determination of metformin and glipizide, gliclazide, glibenclamide or glimperide in plasma. Several extraction and HPLC methods have been described previously for the determination of each of these analytes in plasma separately. The simultaneous determination of these analytes is important for the routine monitoring of diabetic patients who take combination medications and for studying the pharmacokinetics of the combined dosage forms. In addition this developed method can serve as a standard method for the plasma determination of these analytes therefore saving time, effort and money. The recoveries of the developed methods were found to be between 76.3% and 101.9%. The limits of quantification were between 5 and 22.5 ng/ml. The intraday and interday precision (measured by coefficient of variation, CV%) was always less than 9%. The accuracy (measured by relative error %) was always less than 12%. Stability analysis showed that all analytes are stable for at least 3 months when stored at -70 degrees C.     

密闭微波辅助间歇提取RP-HPLC测定三七中三种皂苷类化合物

本文建立了采用微波辅助间歇提取三七样品中的皂苷类化合物,并以反相高效液相色谱（RP—HPLC）测定其中三七皂苷R1、人参皂苷Rg1和人参皂苷Rb1含量的实验方法。分别通过单因素实验和正交实验设计,优化了萃取溶剂浓度、溶剂用量、微波功率和微波辐射时间等提取条件。与传统的索氏提取法、冷浸法和超声波提取法比较,微波辅助萃取法具有快速、提取率高、溶剂消耗少等优点,间歇萃取较连续萃取更是大大节省了微波能耗。