Dynamic Microwave-assisted Extraction Research Articles

Dynamic Microwave-Assisted Micelle Extraction Coupled with Cloud Point Preconcentration for the Determination of Triazine Herbicides in Soil.

A green and simple method, dynamic microwave-assisted micelle extraction coupled with cloud point preconcentration, was developed for the determination of triazine herbicides in soil samples. The method has the advantages of those two extraction procedures, which could eliminate the interferences from complex soil samples greatly. Non-ionic surfactant Triton X-114 aqueous solution used as extraction solvent was continuously pumped into soil samples. The resulting extract was heated and centrifuged in the presence of NaCl. After centrifugation, the analytes were enriched into the surfactant-rich phase. No filtration or cleaning steps were required. Several key parameters were investigated. The Box-Behnken design was applied to optimize the experimental factors involved in the dynamic microwave-assisted micelle extraction. Good linearity was observed in the range of 1.00-250.00μgkg-1. The limits of detection were ranged between 0.26 and 1.71μgkg-1. The recoveries of analytes ranged from 80.3 to 98.3% with the relative standard deviations ranging from 1.1 to 6.6%.

Dynamic microwave-assisted extraction combined with liquid phase microextraction based on the solidification of a floating drop for the analysis of organochlorine pesticides in grains followed by GC

A convenient, cost-effective and fast method using dynamic microwave-assisted extraction and liquid phase microextraction based on the solidification of a floating drop was proposed to analyze organochlorine pesticides in grains including rice, maize and millet. Twelve samples can be processed simultaneously in the method. During the extraction process, 10% acetonitrile-water solutions containing 110μL of n-hexadecane were used to extract organochlorine pesticides. Subsequently, 1.0g sodium chloride was placed in the extract, and then centrifuged and cooled. The n-hexadecane drops containing the analytes were solidified and transferred for determination by gas chromatography-electron capture detector without any further filtration or cleaning process. Limits of detection for organochlorine pesticides were 0.97–1.01μg/kg and the RSDs were in the range of 2.6%–8.5%. The developed technology has succeeded in analyzing six real grains samples and the recoveries of the organochlorine pesticides were 72.2%–94.3%. Compared with the published extraction methods, the developed method was used to analyze organochlorine pesticides in grains, being more environmentally friendly, which is suitable for the daily determination of organochlorine pesticides.

Microwave absorption medium-assisted extraction coupled with reversed-phase dispersive liquid-liquid microextraction of triazine herbicides in corn and soybean samples.

A new extraction method, microwave absorption medium-assisted extraction coupled with reversed-phase dispersive liquid-liquid microextraction, was developed for the determination of triazine herbicides in corn and soybean samples. Triazine herbicides were extracted with hexane and then directly enriched into the ionic liquid phase. The purification of sample and concentration of target analytes were performed simultaneously. The method combines the advantages of nonpolar solvent dynamic microwave extraction and reversed-phase dispersive liquid-liquid microextraction, which could greatly simplify the operation and reduce the whole pretreatment time. The Box-Behnken design was used to the optimization of experimental factors involved in the dynamic microwave-assisted extraction. In the present study, good linearity in the range of 5.00-500.00µg/kg was obtained. The limits of detection and quantification varying from 1.3 to 4.2 and 4.1 to 13.9µg/kg were achieved, respectively. The intra- and interday precisions were between 2.7 and 6.9%. The present method was applied to the analysis of corn and soybean samples, and the recoveries of analytes ranged from 80.7 to 106.9% with the relative standard deviations of 2.1-7.8%. The present method shows the potentials of practical applications in the treatment of the complex fatty solid samples.

Dynamic Microwave-assisted Extraction Online Coupled with QuEChERS for the Determination of Organophosphorus Pesticides in Cereals by Gas Chromatography

A rapid analytical method was first developed to detect organophosphorus pesticides(OPPs) in cereals, which used dynamic microwave assisted extraction(DMAE) coupled online with a modified quick, easy, cheap, effective, rugged, and safe(QuEChERS) method. Cereals samples were mixed with a certain amount of quartz, C18 and primary second amine(PSA), and extracted successively with the acetonitrile-water solution(80%, V/V) under microwave irradiation. The obtained eluate was directly introduced into a collection tube containing NaCl and MgSO4. Finally, the supernate was evaporated and reconstructed, and determined by gas chromatographic spectrometry. Some factors affecting the experimental results were studied and optimized. The extraction and purification processes were carried out coinstantaneously and 12 samples could be treated in one step in 4 min. Low limits of detection(0.43–1.31 µg/kg) for OPPs were obtained in cereals. The relative standard deviations(RSDs) were 2.1%–9.3%. The recoveries of OPPs ranged from 76.1% to 100.2%. By combining the advantages of DMAE with QuEChERS, the sample pretreatment process was simple to operate, with little amount of organic solvent. The whole extraction process was completed in a closed environment, therefore it was very appropriate for daily analysis of OPPs in cereals.

Optimization of dynamic-microwave assisted enzymatic hydrolysis extraction of total ginsenosides from stems and leaves of panax ginseng by response surface methodology

Ginseng stems and leaves (GSAL) are abundant in ginsenosides compounds. For efficient utilization of GSAL and the enhancement of total ginsenosides (TG) compound yields in GSAL, TG from GSAL were extracted, using dynamic-microwave assisted extraction coupled with enzymatic hydrolysis (DMAE-EH) method. The extraction process has been simulated and its main influencing factors such as ethanol concentration, microwave temperature, microwave time and pump flow rate have been optimized by response surface methodology coupled with a Box-Behnken design(BBD). The experimental results indicated that optimal extraction conditions of TG from GSAL were as follows: ethanol concentration of 75%, microwave temperature of 60°C, microwave time of 20 min and pump flow rate of 38 r/min. After experimental verification, the experimental yields of TG was 60.62 ± 0.85 mg g−1, which were well agreement with the predicted by the model. In general, the present results demonstrated that DMAE-EH method was successfully used to extract total ginsenosides in GSAL.

Dynamic microwave assisted extraction coupled with matrix solid phase dispersion for the determination of chlorfenapyr and abamectin in rice by LC-MS/MS

Chlorfenapyr and abamectin are two insecticides used commonly in rice-planting to control insects and mites. The residue remained in rice present potential health hazard to consumers. To realize the accurate determination of chlorfenapyr and abamectin in rice samples, a method based on dynamic microwave assisted extraction (DMAE) coupled with matrix solid phase dispersion (MSPD) was established and validated. In the proposed method, microwave energy was introduced into the elution process of MSPD and therefore improved the extraction efficiency. Different parameters affecting the extraction efficiency were studied and optimized, including type of dispersing sorbent, ratio of dispersing sorbent to sample, type of clean-up sorbents, microwave power, extraction solvent, volumes and flow rate of extraction solvent. Under optimal conditions, the interference in rice extract were removed effectively, moreover, the extraction and clean-up were combined in a single step and 15 samples were treated simultaneously with in 4min. Low limits of detection (0.8ng g−1) for chlorfenapyr and abamectin were obtained. The RSDs of intra- and inter-day were in the range of 2.6 to 8.1%. The recoveries of chlorfenapyr and abamectin from rice samples at spiking levels of 5, 50 and 100ng g−1 were 92.1–96.5% and 88.6–91.0%, respectively. Finally, the proposed method was successfully applied to analyze chlorfenapyr and abamectin in six rice samples, and satisfactory results were obtained.

Determination of chlorpyrifos in soils using multi-throughput dynamic microwave-assisted extraction coupled online with salting-out-assisted liquid–liquid extraction followed by LC–MS/MS

ABSTRACTA simple and rapid method based on multi-throughput dynamic microwave-assisted extraction coupled online with salting-out-assisted liquid–liquid extraction was developed for the analysis of chlorpyrifos in soil. First, the chlorpyrifos was extracted with acetonitrile aqueous (50%, v/v) under the action of microwave energy. Then the obtained extract was separated clearly and easily into an acetonitrile phase and an aqueous phase with the assistance of ammonium acetate. The acetonitrile phase containing chlorpyrifos was concentrated and determined by liquid chromatography–tandem mass spectrometry. The effects of parameters on extraction efficiency including microwave power, extraction solvent, volumes and flow rate of extraction solvent, sample pH, types and amount of salt were studied and optimised. To eliminate the matrix effect, validation of the method was carried out using the matrix-based calibration curve. The limits of detection and quantification for chlorpyrifos were 0.17 and 0.5 ng g−1, respectively. The proposed method was applied to analyse chlorpyrifos in five soil samples and verified by the recovery test. The recoveries of chlorpyrifos at three spiked levels (5, 50, 200 ng g−1) were in the range of 90.0–100.5%, with relative standard deviations varying from 1.3% to 5.7%. Compared with the methods reported previously, the proposed method can simplify the operation procedure and reduce solvent consumption in sample pretreatment.

Analysis of sulfonamides in soil, sediment, and sludge based on dynamic microwave-assisted micellar extraction.

A green and high-throughput analytical method was described for the simultaneous determination of ten sulfonamides (SAs) from soil, sediment, and sludge in northeast China. None of potentially hazardous organic solvents was used in the whole sample preparation procedure, and the total preparation time of 15 samples was about 18min. The limits of detection for the SAs were in the range of 0.42-0.68ngg(-1). The intra-day and inter-day precisions, expressed by the relative standard deviation, were below 7%. Under the optimum conditions, the recoveries of ten SAs were between 69.7 and 102.7%. The proposed method was successfully applied to analyze the SAs residues in agricultural soils, river sediments, and sewage sludge. SAs were found at the levels of 1.40-2.31ngg(-1) and 3.77-29.29ngg(-1) in the sediments and sludge, respectively. The aging effect of spiked soil samples on the SAs recoveries was examined, and the results demonstrate that eight SAs could persist in five soils for 3months. Compared with the traditional method, the proposed method could reduce the consumption of the organic solvent, shorten the sample preparation time, and increase the sample throughput.

High-throughput dynamic microwave-assisted extraction coupled with liquid–liquid extraction for analysis of tetrabromobisphenol A in soil

Fifteen soil samples can be treated simultaneously in 20 min with low cost and less solvent by the proposed method.

Optimization, characterization, and biological activity of polysaccharides from Berberis dasystachya Maxim

In this study, the extraction of water-soluble polysaccharides (BDPs) from Berberis dasystachya Maxim using dynamic microwave-assisted extraction (DMAE) was discussed. A Box–Behnken design combined with response surface methodology has been employed to optimize extraction parameters of DMAE. The BDPs have been analyzed in order to identify a variety of chemical properties. Antioxidant and anti-tumor activities in vitro have been studied by DPPH, ABTS, reducing power assay, and MTT assay, respectively. The results obtained showed that the optimal extraction conditions were as follows: ratio of water to raw material (X1) 25.84mg/L, extraction power (X2) 433.13W, extraction time (X3) 35.18min, and the maximum yield of extraction was 6.472±0.384%, which was in good agreement with the predicted value. The physicochemical tests demonstrated that the BDPs mainly consist of rhamnose, arabinose, xylose, mannose, glucose and lactose in a molar ratio of 1:17.3:1.33:7:2.33:1.78; the average molecular weight of the BDPs was estimated to be from 2.95×105 and 1.52×103Da, respectively. Furthermore, the BDPs exhibited effective antioxidant and anti-proliferative properties in vitro. Such pharmaceutical activities could prove useful for potential future applications involving the berries of B. dasystachya Maxim.

Optimization of dynamic microwave-assisted extraction of Armillaria polysaccharides using RSM, and their biological activity

We used the Box–Behnken design to optimize polysaccharide extraction from Armillaria luteo-virens (Alb. et Schw. Fr.) Sacc. The independent factors included extraction time (X1), microwave power (X2) and water to raw material ratio (X3). The experimental values were fitted to a second-order polynomial equation using multiple regression analysis and a statistical method. Analysis of Variance results indicated that all factors including X1 – X3 had an impact on Armillaria luteo-virens (Alb. et Schw. Fr.) Sacc. polysaccharide extraction. The optimal conditions for efficient yield of polysaccharide, giving a maximum yield of 8.43%, were: X1 = 30.24 min, X2 = 600.6 W and X3 = 40 mL/g. The model was verified by modifying the optimal conditions (X1 = 30 min, X2 = 601 W and X3 = 40 mL/g) for practical application. A pilot scale test was also carried out under optimal conditions. The obtained yields 8.40 ± 0.12% and 8.34 ± 0.25% were comparable with the optimized condition, which indicated that our model is accurate. Fourier transform infrared spectroscopy characterization revealed that the extracted polysaccharide produced typical absorption peaks. Oxygen radical absorbance capacity results showed the polysaccharides had good potential as an antioxidant. Moreover, the polysaccharide showed relatively strong inhibitory activity on the growth of NCI–H446 cells.

Dynamic microwave-assisted extraction combined with continuous-flow microextraction for determination of pesticides in vegetables

A simple, rapid, solventless and cost-effective dynamic microwave-assisted extraction (DMAE) combined with continuous-flow microextraction (CFME) system was firstly assembled and validated for extraction of eight organophosphorus pesticides in vegetables. The method combines the advantages of DMAE and CFME, and extends the application of the single drop microextraction to complex solid samples. The extraction, separation, and enrichment were performed in a single step, which could greatly simplify the operation and reduce the whole pretreatment time. In the developed method, analytes were first extracted from the vegetables using 3% NaCl solution as extraction solvent, then concentrated into microextraction solvent. After extraction, the microextraction solvent containing the enriched analyte was directly analyzed by GC–MS without any filtration or clean-up process. Several parameters affecting the extraction efficiency were investigated and optimized. Real vegetable samples were analyzed, satisfactory recoveries were obtained in the range of 80.7–106.7%, and relative standard deviations were lower than 8.7%.

Dynamic microwave-assisted extraction online coupled with single drop microextraction of organophosphorus pesticides in tea samples

A new method for the determination of seven organophosphorus pesticides was developed using dynamic microwave-assisted extraction online coupled with single drop microextraction prior to gas chromatographic mass spectrometry (GC–MS). The method combines the advantages of dynamic microwave-assisted extraction and single-drop microextraction, which could greatly simplify the operation and reduce the whole pretreatment time. In the developed method, tea samples were extracted with 25% ethanol aqueous solution and purified with acidic alumina at the same time, and then the analytes were concentrated into microextraction solvent. When the extraction was completed, the solvent microdrop containing the enriched analytes was retracted into the microsyringe and directly analyzed by GC–MS without any filtration or cleanup step. The method makes extraction, cleanup, separation, and enrichment to be carried out in one step. Several experimental parameters, including type of extraction solvent, type and amount of dispersant, type and volume of microextraction solvent, microwave power, extraction time, and flow rate of extraction solvent were investigated and optimized. Under optimal experimental conditions, good linearity was observed in the range of 2.00–500.00μgkg−1. The limits of detection and quantification were in the range of 0.4–1.7μgkg−1 and 1.1–5.6μgkg−1, respectively. The present method was applied to the analysis of tea samples, and the recoveries of analytes were in the range of 84.9–106.4% with the relative standard deviations ranging from 1.0 to 6.1%. The results showed that the present method was a rapid and feasible method for the determination of organophosphorus pesticides in tea samples.

Dynamic microwave-assisted extraction of total ginsenosides from ginseng fibrous roots

A dynamic microwave-assisted extraction (DMAE) method is established for the extraction of total ginsenosides from ginseng fibrous roots. The extraction process has been simulated and its main affection factors (liquid/solid ratio K of solvent to ginseng powders (V/m), irradiation time, irradiation temperature, extracting solution concentration, flow rate of solvent and microwave power) have been optimized by response surface methodology (RSM). The optimum conditions of extraction are the liquid/solid ratio of 270 mL/g, the extraction temperature of 75 °C, the extraction time of 35 min, ethanol concentration of 70% (V/V), the solvent flow rate of 1.3 mL/min, and the microwave power of 500 W. The yield of ginsenosides obtained by the proposed DAME method is (15.0±0.7) %, which is well agreement with the yield predicted by the model. Compared with static microwave-assisted extraction, DMAE has a higher extraction yield and can avoid the degradation of ginsenoside.

Determination of triazine herbicides in fresh vegetables by dynamic microwave-assisted extraction coupled with homogeneous ionic liquid microextraction high performance liquid chromatography.

A novel extraction method, dynamic microwave-assisted extraction coupled with homogeneous ionic liquid microextraction, was developed for the determination of triazine herbicides, including desmetryn, terbumeton, propazine, terbuthylazine, dimethametryn, and dipropetryn in fresh vegetable samples by high performance liquid chromatography (HPLC). In the developed method, 120 μL of 1-butyl-3-methylimidazolium tetrafluoroborate ([C4MIM][BF4]) was added to 10 mL of aqueous solution containing 0.3 g of NaCl to obtained the extraction solvent. Six triazines could be extracted completely within 4 min by the present method. Then, [NH4][PF6] was added into the extract to form a water-insoluble ionic liquid [C4MIM][PF6] via a simple metathesis reaction, and the analytes were enriched into the ionic liquid phase. After centrifugation and dilution with acetonitrile, the resulting solution was analyzed directly by HPLC. The effects of some experimental parameters, including type and volume of ionic liquid, volume of extraction solvent, amount of ion-pairing agent [NH4][PF6], salt concentration, microwave power, and flow rate of extraction solvent on the extraction efficiency were investigated and optimized. Under the optimum experimental conditions, the linearity for determining the analytes was in the range of 2.50-250.00 μg kg(-1), with the correlation coefficients ranging from 0.9989 to 0.9999. When the present method was applied to the analysis of vegetable samples, satisfactory recoveries were obtained in the range of 76.8%-106.9%, and relative standard deviations were lower than 9.8%.

Integrated microwave processing system for the extraction of organophosphorus pesticides in fresh vegetables

A simple and efficient integrated microwave processing system (IMPS) was firstly assembled and validated for the extraction of organophosphorus pesticides in fresh vegetables. Two processes under microwave irradiation, dynamic microwave-assisted extraction (DMAE) and microwave-accelerated solvent elution (MASE), were integrated for simplifying the pretreatment of the sample. Extraction, separation, enrichment and elution were finished in a simple step. The organophosphorus pesticides were extracted from the fresh vegetables into hexane with DMAE, and then the extract was directly introduced into the enrichment column packed with active carbon fiber (ACF). Subsequently, the organophosphorus pesticides trapped on the ACF were eluted with ethyl acetate under microwave irradiation. No further filtration or cleanup was required before analysis of the eluate by gas chromatography–mass spectrometry. Some experimental parameters affecting extraction efficiency were investigated and optimized, such as microwave output power, kind and volume of extraction solvent, extraction time, amount of sorbent, elution microwave power, kind and volume of elution solvent, elution solvent flow rate. Under the optimized conditions, the recoveries were in the range of 71.5–105.2%, and the relative standard deviations were lower than 11.6%. The experiment results prove that the present method is a simple and effective sample preparation method for the determination of pesticides in solid samples.

Optimization of polysaccharides from Lycium ruthenicum fruit using RSM and its anti-oxidant activity

Dynamic microwave-assisted extraction (DMAE) technique was employed for the extraction of polysaccharides from Lycium ruthenicum (LRP). The extracting parameters were optimized by using three-variable-three-level Box–Behnken design and response surface methodology (RSM) based on the single-factor experiments. RSM analysis indicated good correspondence between experimental and predicted values. The optimum extraction parameters for the yield of polysaccharide were ratio of water to raw material 31.5mL/g, extracting time 25.8min and microwave power 544.0W. Polysaccharide was analyzed by chemical methods and Fourier-transform infrared (FT-IR). The antioxidant activities of LRP were investigated including scavenging activity of 2,2-diphenyl-1-picrylhydrazyl (DPPH), hydrogen peroxide and free radicals of superoxide anion in vitro. The results of antioxidant activity exhibited LRP had the potential to be explored as novel natural antioxidant for using in functional foods or medicine.

Dynamic Microwave-Assisted Extraction Coupled with Salting-Out Liquid–Liquid Extraction for Determination of Steroid Hormones in Fish Tissues

In this work, a simple and fast sample pretreatment method was proposed for determination of steroid hormones in fish tissues by coupling dynamic microwave-assisted extraction with salting-out liquid-liquid extraction. The steroid hormones were successively extracted with acetonitrile and water under the action of microwave energy. Subsequently, the extract was separated into an acetonitrile phase and an aqueous phase with ammonium acetate. The acetonitrile phase containing the target analytes was concentrated and determined by LC-MS/MS. The limits of detection for the steroid hormones were in the range of 0.03-0.15 ng g(-1). This method was successfully applied to analyze seven kinds of fish tissues, and the recoveries of the steroid hormones for the spiked samples were in the range of 75.3 ± 4.9% to 95.4 ± 6.2%. Compared with the traditional method, the proposed method could reduce the consumption of the organic solvent, shorten the sample preparation time, and increase the sample throughput.

On‐line ionic liquid‐based dynamic microwave‐assisted extraction‐high performance liquid chromatography for the determination of lipophilic constituents in root of Salvia miltiorrhiza Bunge

On-line continuous sampling, ionic liquid-based dynamic microwave-assisted extraction high performance liquid chromatography has been developed and applied to the extraction of lipophilic constituents from root of Salvia miltiorrhiza Bunge. Several operating parameters were optimized by single-factor and Box-Behnken design experiments. The type and concentration of ionic liquids, power of microwave irradiation, flow rate of sample suspension, amount, and particle size of sample were investigated. The limits of detection for tanshin-one I, cryptotanshinone, and tanshinone II(A) are 0.014, 0.009, and 0.009 mg/g, respectively. The RSDs of interday and intraday were lower than 2.02 and 2.16%, respectively. The recoveries for target analytes were in the range of 90.7-101.8%. The homogeneity of the suspension and stability of the analytes were investigated and the results were satisfactory. The proposed method was compared with the off-line ionic liquid-based dynamic microwave-assisted extraction, off-line ethanol-based dynamic microwave-assisted extraction, ionic liquid-based ultrasonic-assisted extraction, and ionic liquid-based maceration extraction. The results indicated that the proposed method is effective for the extraction of the active components in Chinese herbal medicine and has some advantages over the other methods.

Fast Determination of Paeonol from Cortex moutan by Microwave-Assisted Steam Extraction Followed by HPLC

In this work, microwave-assisted steam extraction (MASE) followed by high performance liquid chromatography is described for the extraction and determination of paeonol in Cortex moutan. This new approach was based on the combination of microwave-assisted extraction and steam distillation. No organic solvent was used and no clean-up step was required before chromatographic analysis. The extraction vessel and water were both under microwave radiation: the water was still heated while the generated steam flowed through the sample. Factors such as collection volume, microwave power, mass of the sample, and mixed proportion of the sample and quartz sand were investigated. The intra- and inter-day relative standard deviation values of <9 % show that the proposed method had good repeatability. To demonstrate its feasibility, the MASE was compared with other extraction methods such as dynamic microwave-assisted extraction, ultrasonic extraction, and steam distillation, and the experimental results show that the MASE was a rapid, effective, and environmentally friendly alternative for the extraction of paeonol in Cortex moutan. Finally, the proposed method was applied on Cortex moutan samples from different producing areas and the results were satisfactory.