Microwave-assisted Extraction Solvent Research Articles

Optimization of saponin extracts using microwave-assisted extraction as a sustainable biopesticide to reduce Pomacea canaliculata population in paddy cultivation

This study highlights the optimum conditions to extract saponins from Furcraea selloa var. marginata (Furcraea leaves) and spent tea leaves (STL) using supercritical-CO2 (ScCO2) and microwave. The bioactivity effects of saponins towards golden apple snails, Pomacea canaliculata were shown. The experiment was designed using the response surface methodology (RSM) to determine the optimum conditions for both extractions technique. Based on RSM analysis, the highest yield of saponins was obtained at 21.60 MPa, 0.30 mm particle size and 4.62 ml/min CO2 for 30 min using ScCO2 extraction. Meanwhile, in microwave-assisted extraction (MAE), the highest yield obtained was at 90 °C, 9 min of extraction time and 23.54 ml solvent per gram of sample. The effect of solvent was also investigated. Using water as co-solvent in ScCO2 extraction and as solvent in MAE resulted in better yield of saponins. Overall, MAE was more efficient to extract saponins with 3.43 wt% compared to ScCO2 extraction with only 0.49 wt%. The efficacy test of synthesized biopesticides against golden apple snails (GAS) proved that Furcraea leaves extract is the active ingredient to produce effective biopesticide as its performance was able to increase the mortality of GAS up to 100% within 24 h observation and enhanced the paddy growth at early stage of cultivation.

Recycling of Tea Waste: Simple and Effective Separation of Caffeine and Catechins by Microwave Assisted Extraction (MAE)

This study was designed to develop a cost effective green extraction method to separate valuable chemicals from black tea waste (BTW) and tea dust called “caffeine dust” (CD). These materials are totally unwanted residue and treated as rubbish. Two extraction methods were used for extraction of waste materials obtained in three collection periods. In conventional extraction method, material was subjected to hot water extraction at 80 o C for 40 minutes. In microwave assisted extraction (MAE) method, different eco-friendly aqueous solvents (water, citric acid-water or ethanol-water) were used under a controlled 600 W microwave power at 80 o C for only 4 minutes treatment in a close microwave system. MAE and conventional method gave similar extract yields for both waste materials but MAE was more successful and economical completing the extraction in shorter time. Using citric acid-water solvent in MAE significantly increased the extraction of individual catechins such as epicatechin (EC) and epigallocatechin gallate (EGCG). This study showed that tea waste could be utilized for production of valuable chemicals using nontoxic solvents at extremely short extraction periods.

New Approaches for Effective Microwave Assisted Extraction of Caffeine and Catechins from Green Tea

This study was designed to develop an effective microwave assisted extraction (MAE) method for extraction of caffeine and catechins from green tea samples. A series of solvents (water, ethanol:water mixture or citric acid:water mixture) were used for extraction of green tea samples (fresh, frozen or dried) collected in three collection periods (first, second and third collection periods). Tea samples were extracted using water in a close microwave system under the certain extraction conditions. Extraction was carried out under a controlled 600 W microwave power at 80 oC temperature for 4 min irradiation time. Alternative to water, an ethanol-water mixture (1:1) or a citric acid-water (1:1) mixture was used as extracting solvent under the same conditions. After MAE crude aqueous extract was partitioned first with chloroform to separate caffeine then ethyl acetate for catechins. Both caffeine and catechin extraction was quite successful with microwave assisted system employing only 4 minutes treatment. The highest caffeine yield was obtained in the second collection period using frozen green tea samples and ethanol-water as extracting solvent. The yield of catechin extracts was between 0.84-3.96% depending on the solvent system used for extraction. Ethanol-water mixture seems to be appropriate for effective extraction in the basis of extract yields. However, HPLC results showed that individual catechin content of each extraction is more important criteria for the evaluation of most effective extraction medium rather than the mass of the extract. Using citric acid as extracting solvent in MAE seem to be more fruitful providing 100% catechin mixture with the highest EGCG content.

Microwave assisted extraction of ketamine and its metabolites from skeletal tissues

The use of Microwave Assisted Extraction (MAE) to extract ketamine and its metabolites from decomposed bone tissue is described. Wistar rats received 75 mg kg−1 (i.p.) ketamine (n = 12) or remained drug-free (controls, n = 4). Following euthanasia, rats were allowed to decompose to skeleton outdoors. Bones (vertebrae, rib, pelvi, femora, tibiae, humeri and scapulae) were collected and pooled. Analyte stability to MAE in methanol or acetone–hexane mixture (1 : 1, v/v) in a closed vessel microwave system was assessed, and acetone–hexane was chosen as the MAE solvent. Bone samples underwent MAE, and extracts were assayed using microplate solid phase extraction (MPSPE) in a mixed-mode configuration and gas chromatography-mass spectrometry. Drug levels, expressed as mass normalized response ratios, were used to characterize extraction time and the effect of MAE solvent volume on the extraction time and relative recovery for each analyte. Extraction time varied slightly with solvent volume, while relative analyte recovery did not differ significantly. Recovery was at least 90% of maximal value within the first 5 min for all samples examined and maximum recovery occurred within 20 minutes. MAE in combination with MPSPE offers a substantial improvement in analytical throughput for toxicological analysis of skeletal remains.

Study of polyethylene glycol as a green solvent in the microwave-assisted extraction of flavone and coumarin compounds from medicinal plants

In this paper, the application of polyethylene glycol (PEG) aqueous solution as a green solvent in microwave-assisted extraction (MAE) was firstly developed for the extraction of flavone and coumarin compounds from medicinal plants. The PEG solutions were optimized by a mono-factor test, and the other conditions of MAE including the size of sample, liquid/solid ratio, extraction temperature and extraction time were optimized by means of an orthogonal design L 9 (3 4). Subsequently, PEG-MAE, organic solvent-MAE, and conventional heating reflux extraction (HRE) were evaluated with nevadensin extraction from Lysionotus pauciflorus, aesculin and aesculetin extraction from Cortex fraxini. Furthermore, the mechanism of PEG-MAE was investigated, including microwave-absorptive property and viscosity of PEG solutions, the kinetic mechanism of PEG-MAE and different microstructures of those samples before and after extraction. Under optimized conditions, the extraction yields of nevadensin from L. pauciflorus, aesculin and aesculetin from C. fraxini were 98.7%, 97.7% and 95.9% in a one-step extraction, respectively. The recoveries of nevadensin, aesculin and aesculetin were in the range of 92.0–103% with relative standard derivation lower than 3.6% by the proposed procedure. Compared with organic solvent-MAE and conventional extraction procedures, the proposed methods were effective and alternative for the extraction of flavone and coumarin compounds from medicinal plants. On the basis of the results, PEG solution as a green solvent in the MAE of active compounds from medicinal plants showed a great promising prospect.

Evaluation of Microwave-Assisted Extraction for the Analysis of Polychlorinated Biphenyls and Organochlorine Pesticides in Fish

The efficiency of microwave-assisted extraction (MAE) was evaluated for the analysis of polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) in fish. An isotope dilution method was used for quantification via analysis of the samples by gas chromatography and mass spectrometry. MAE solvent, temperature, and time were optimized, and observed concentrations were compared. The MAE results were also compared to those of other extraction techniques (Soxhlet extraction, pressurized liquid extraction, saponification, and homogenization). Concentrations of PCBs and OCPs obtained by MAE at 120 degrees C for 10 min were comparable to those by the other techniques. The results suggest that MAE can be used for the analysis of PCBs and OCPs in fish.

Application of microwave-assisted extraction to the analysis of PCBs and CBzs in fly ash from municipal solid waste incinerators

Polychlorinated biphenyls (PCBs) and chlorobenzenes (CBzs) are two classes of dioxin precursors formed in municipal solid waste incinerators (MSWIs) producing negative health effects similar to those of dioxins. Reducing the analytical time required for determining the concentrations of these compounds in MSWIs is important for quickly evaluating their importance and associated health risks. In the present study, microwave-assisted extraction (MAE) is compared with traditional Soxhlet extraction (SE) to determine the extraction efficiencies attained for PCB and CBz analysis. The efficiencies of MAE are compared with those of SE under various experimental conditions, using fly ash spiked with standards. Water is used as a safe and environmentally friendly solvent in MAE for PCB and CBz analyses and MAE has high extraction efficiency for spiked fly ash compared with that of SE. Furthermore, the extraction time and organic solvent consumption are reduced with MAE compared with SE. The optimum conditions for MAE established in this study are using a 30-ml volume of toluene/acetone (1/1) or a 15-ml volume of toluene, samples with less than 60% water content (WC), and an irradiation time of 15min.

Optimization of an analytical procedure for the determination of banned azo dyes in leather

The possibility of improving an existing method, based on supercritical-fluid extraction (SFE) and microwave-assisted extraction (MAE), for the determination of banned azo dyes in leather has been studied. Thus, optimization of experimental conditions in different steps (degreasing, reduction, and extraction) of the analytical procedure was performed. The influence of different variables (reaction time, temperature, and concentration of reducing agent) on the reduction process was evaluated by use of a factorial design. It was found that the concentration of the reducing agent and the interaction between time and temperature were the most influential variables. Consequently, by applying a higher temperature, the reaction time could be halved. The use of acidified water as extraction solvent in MAE was also investigated. Usually 1 mol L(-1) HCl was superior to methanol and buffer in terms of extraction efficiency. In conclusion, the present method gave significantly higher recoveries in comparison with the original method. All dyes were determined indirectly by measuring their corresponding harmful amines, formed after reduction by use of sodium dithionite.

Application of water as a solvent in microwave-assisted extraction for analysis of PCBs and CBzs in fly ash

Polychlorinated biphenyls (PCBs) and chlorobenzenes (CBzs) are two classes of dioxin precursors formed in municipal solid waste incinerators (MSWIs); they produce negative health effects similar to those of dioxins. Reducing the analytical time required for determining the concentrations of these compounds in MSWIs is important for quickly evaluating their importance and assessing associated health risks. In the present study, water is used as a safe and environmentally friendly solvent in microwave-assisted extraction (MAE) for PCB and CBz analyses. MAE is compared with traditional Soxhlet extraction (SE) to determine the extraction efficiencies. The evaluation of extraction efficiencies shows that MAE has a high extraction efficiency compared with that of SE when water content is lower than 60%. Furthermore, the extraction time and organic solvent consumption are reduced with MAE compared with SE.