Simultaneous Microwave-assisted Extraction Research Articles

Simultaneous microwave-assisted extraction of bioactive compounds from aged garlic

In this work, the simultaneous extraction of bioactives (organosulfur compounds, such as S-allyl-L-cysteine (SAC), carbohydrates, such as neokestose and neonystose, and total phenolic compounds) from aged garlic has been optimized for the first time to obtain multifunctional extracts for further application as food ingredients. Analytical methods using liquid chromatography coupled to mass spectrometry (HPLC-MS) and by hydrophilic interaction liquid chromatography with evaporative light scattering detection (HILIC-ELSD) were also previously optimized. High sensitivity (limits of detection between 0.013 and 0.77 µg mL−1) and appropriate repeatability (< 12%) and accuracy (> 92%) for the analysis of bioactives were achieved. After selecting water as the extraction solvent and microwave-assisted extraction (MAE) as the most efficient technique, operation conditions were optimized using a Box-Behnken experimental design (60 min; 120 °C; 0.05 g mL−1; 1 cycle) to maximize the content of bioactives from different aged garlic samples. Regarding organosulfur compounds, only SAC (traces-2.32 mg g−1 dry sample) and cycloalliin (1.23–3.01 mg g−1 dry sample) were detected in all samples, while amino acids such as arginine (0.24–3.45 mg g−1 dry sample) and proline (0.43–3.91 mg g−1 dry sample) were, in general, the most abundant. Bioactive carbohydrates (from trisaccharides to nonasaccharides) were only detected in fresh garlic and aged garlic processed under mild conditions, whereas all garlic extracts showed antioxidant activity. The developed MAE methodology is shown as a successful alternative to other procedures for the simultaneous extraction of aged garlic bioactives intended by the food and nutraceutical industries, among others.

A high throughput method for fatty acid profiling using simultaneous microwave-assisted extraction and derivatization followed by reversed fill/flush flow modulation comprehensive multidimensional gas chromatography

The fatty acid composition of a food product provides information regarding the origin of the product and its overall quality, such as its nutritional value. This work proposes a fast and accurate method for preparing fatty acid methyl esters from a wide variety of food products by using a single-step microwave-assisted extraction and derivatization coupled to reversed fill/flush flow modulation comprehensive two-dimensional gas chromatography (GC×GC) – flame ionization detector (FID) to tentatively identify and quantify the individual fatty acid. The robustness of the GC×GC – FID platform was successfully assessed, as well as the reliability of the entire proposed procedure, assuring repeatability largely below 10%. The enhanced separation obtained by the use of GC×GC allowed for the identification of 81 FAMEs in a single run of 30 min. The fatty acid methyl esters profiles obtained with the proposed microwave-assisted extraction and derivatization were comparable with reference methods from the literature and the American Oil Chemistry Society. This method also proved to be a significant step towards a greener procedure than the reference one when evaluated based on the PrepAGREE metrics that have been recently proposed.

Extraction of Antioxidant Compounds from Onion Bulb (Allium cepa L.) Using Individual and Simultaneous Microwave-Assisted Extraction Methods.

Despite the excellent beneficial properties that anthocyanins and total phenolic compounds give to the red onion bulbs, few articles have investigated modern extraction techniques or experimental designs in this field. For this reason, the present study proposes the development and optimization of alternative methods for the extraction of these compounds based on microwave-assisted extraction and the Box-Behnken experiment design. The optimal values for the extraction of total anthocyanins have been established at 62% methanol composition as a solvent, pH 2, 56 °C temperature, and 0.2:13 g:mL sample-solvent ratio. Regarding the extraction of total phenolic compounds, the optimal conditions have been established at 100% pure methanol as a solvent with pH 2, 57 °C temperature, and 0.2:8.8 g:mL sample-solvent ratio. Short extraction times (min), good recoveries (mg of bioactive compound g−1 of dry onion), and high repeatability and intermediate precision (coefficient of variation (%)) have been confirmed for both methods. Regarding total anthocyanins, the following results have been obtained: 2 min, 2.64 ± 0.093 mg of total anthocyanins g−1 of dry onion, and 2.51% and 3.12% for precision. Regarding phenolic compounds, the following results have been obtained: 15 min, 7.95 ± 0.084 mg of total phenolic compound g−1 of dry onion, and 3.62% and 4.56% for precision. Comparing these results with those of other authors and with those obtained in a previous study of ultrasound-assisted extraction, it can be confirmed that microwave-assisted extraction is a quantitative, repeatable, and very promising method for the extraction of phenolic compounds and anthocyanins, which offers similar and even superior results with little solvent expense, time, and costs.

Screening the elite chemotypes of Gloriosa superba L. in India for the production of anticancer colchicine: simultaneous microwave-assisted extraction and HPTLC studies

BackgroundGloriosa superba L. (Colchicaceae) is a high-value medicinal plant indigenous to Africa and Southeast Asia. Its therapeutic benefits are well-established in traditional medicines including Ayurveda. It is well known for its natural bioactive compound colchicine which exhibits a wide range of pharmacological activities i.e. rheumatism, gout and was also introduced into clinical practices. The increasing demand as well as its illegal harvesting has brought this valuable plant under threatened category.MethodsThe present investigation describes a microwave assisted extraction (MAE) strategy coupled with a densitometric-high performance thin layer chromatographic (HPTLC) methodology for the analysis of colchicine from 32 different populations of G. superba. A Box-Behnken statistical design (3 level factor) has been employed to optimize MAE, in which power of microwave, time of irradiation, aqueous ethanol and pH were used as independent variables whereas colchicine was used as the dependent variables. Chromatography was carried out on Silica gel 60 F254 TLC plates with toluene: methanol, 85:15 (v/v) being used as solvent system. Densitometric measurement was performed at λ=254 nm following post-derivatization (10% methanolic sulphuric acid).ResultsOptimal conditions for extraction to obtain the maximum colchicine yield was found to be 7.51 mg g− 1 which was very close to be predicted response 7.48 mg g− 1 by maintaining microwave power (460 W), irradiation time (6.4 min), aqueous ethanol-30, pH -3. Colchicine content ranged between 2.12–7.58 mg g− 1 among 32 G. superba populations in which only three chemotypes viz. GS- 1, GS- 3, and GS- 2 collected from West Bengal and Sikkim, respectively exhibited maximum yield of colchicine.ConclusionTherefore, this newly developed optimized MAE coupled with HPTLC densitometry methodology not only quantifies colchicine in order to identify elite chemotypes of G. superba, but it also encourages in selecting high yielding populations of the plants for industrial use and economic boost for the farmers. This validated, simple and reproducible HPTLC protocol is being used for the first time to estimate colchicine from natural populations of G. superba obtained from 32 different geographical regions of India.Graphical abstract

Microwave assisted saponification (MAS) followed by on-line liquid chromatography (LC)–gas chromatography (GC) for high-throughput and high-sensitivity determination of mineral oil in different cereal-based foodstuffs

A high throughput, high-sensitivity procedure, involving simultaneous microwave-assisted extraction (MAS) and unsaponifiable extraction, followed by on-line liquid chromatography (LC)–gas chromatography (GC), has been optimised for rapid and efficient extraction and analytical determination of mineral oil saturated hydrocarbons (MOSH) and mineral oil aromatic hydrocarbons (MOAH) in cereal-based products of different composition. MAS has the advantage of eliminating fat before LC–GC analysis, allowing an increase in the amount of sample extract injected, and hence in sensitivity. The proposed method gave practically quantitative recoveries and good repeatability. Among the different cereal-based products analysed (dry semolina and egg pasta, bread, biscuits, and cakes), egg pasta packed in direct contact with recycled paperboard had on average the highest total MOSH level (15.9mgkg−1), followed by cakes (10.4mgkg−1) and bread (7.5mgkg−1). About 50% of the pasta and bread samples and 20% of the biscuits and cake samples had detectable MOAH amounts. The highest concentrations were found in an egg pasta in direct contact with recycled paperboard (3.6mgkg−1) and in a milk bread (3.6mgkg−1).

A simultaneous microwave-assisted extraction and adsorbent treatment process under acidic conditions for recovery and separation of paclitaxel from plant cell cultures

We have developed a simultaneous microwave-assisted extraction and adsorbent treatment process under acidic conditions to increase the recovery and separation efficiency of the anticancer agent paclitaxel from plant cell culture. The simultaneous process under the conditions of extracting solution (90% aqueous methanol), pH 2.2, extraction time, 6min, ratio of extracting solution to biomass, 1: 1 (v/w), extraction temperature, 40 °C, adsorbent type, sylopute, and ratio of adsorbent to biomass, 0.08: 1 (w/w), facilitated 1.97-fold higher recovery of paclitaxel in a shorter extraction time than the conventional solvent extraction process. In addition, biomass-derived tar compounds were successfully removed by the simultaneous process alone (average removal >97%). Using the simultaneous process, the paclitaxel extraction efficiency was improved, biomass-derived tar compounds were removed, and the purification process was simplified at the same time.

Development and application of microwave assisted extraction (MAE) for the extraction of five polycyclic aromatic hydrocarbons in sediment samples in Johannesburg area, South Africa

A microwave-assisted extraction (MAE) method was verified and applied for the extraction of polycyclic aromatic hydrocarbons (PAHs) in sediment samples. Soxhlet extraction was used as the reference method. The optimum MAE was carried out with 20mL of hexane/acetone (1:1, v/v) mixture in a 1-g sample at 250W for 20min. Soxhlet extraction was carried out with 250mL of dichloromethane:hexane (1:1, v/v) mixture in a 15-g sample for 24h in a water bath maintained at 60°C. The collected extracts were both cleaned up, reduced to 1mL under nitrogen and then injected into an HPLC fluorescence. To increase the sample throughput, simultaneous MAE was performed. The obtained percentage recoveries ranged from 61 to 93 and 88-98 for MAE and SE, respectively. The optimised MAE method was validated using certified reference material. It was then applied to real sediment samples from in and around the greater Johannesburg area. The sediments from Jukskei River were found to be the most polluted while Hartbeespoort Dam sediments were found to be least polluted. The overall order of concentrations for the studied PAHs per site was as follows: Jukskei River > Kempton Park > Centurion Dams > Natalspruit River (PIT) > Hartbeespoort Dam.

Microwave-Assisted Method for Simultaneous Extraction and Hydrolysis for Determination of Flavonol Glycosides in Ginkgo Foliage Using Brönsted Acidic Ionic-Liquid [HO3S(CH2)4mim]HSO4 Aqueous Solutions

The Brönsted acidic ionic-liquid [HO3S(CH2)4mim] HSO4, a novel dual catalyst–solvent, has been successfully applied in simultaneous microwave-assisted extraction and hydrolysis for the determination of flavonol glycosides in Ginkgo foliage. The parameters, namely the [HO3S(CH2)4mim]HSO4 concentration, microwave-irradiation power, microwave-irradiation time, and solid–liquid ratio, were optimized. The optimum conditions were: an amount of 1.5 M [HO3S(CH2)4mim]HSO4, a microwave-irradiation power of 120 W, an irradiation time of 15 min, and a solid–liquid ratio of 1:30 g/mL. Compared with traditional methods the proposed approach demonstrates higher efficiency in a shorter operating time, and is an efficient, rapid, and simple sample preparation method.

Development and optimization of a novel simultaneous microwave-assisted extraction and adsorbent treatment process for separation and recovery of paclitaxel from plant cell cultures

A novel simultaneous microwave-assisted extraction (MAE) and adsorbent treatment process was developed for recovering the anticancer agent paclitaxel from plant cell cultures and removing plant-derived tar and waxy compounds. The efficiency of the process was maximized by optimizing several major process variables. The optimal extraction time, ratio of adsorbent to liquid–liquid extract, ratio of methanol to biomass and extraction temperature were found to be 6 min, 4.5:1 (w/w), 1:1 (v/w) and 40 °C, respectively. By performing the simultaneous process under these conditions, we were able to recover most of the paclitaxel (>99%) with a purity of ∼22% after hexane precipitation. The efficiency of this process is similar to that of the conventional process (purity: ∼20%, yield: ∼95%) in which paclitaxel recovery is separate from adsorbent treatment. Therefore, it is expected that the conventional process can be simplified by simultaneously performing paclitaxel recovery and removal of impurities, thus dramatically reducing the cost of separation/purification.

Sample preparation of sewage sludge and soil samples for the determination of polycyclic aromatic hydrocarbons based on one-pot microwave-assisted saponification and extraction

A microwave-assisted sample preparation (MASP) procedure was developed for the analysis of polycyclic aromatic hydrocarbons (PAHs) in sewage sludge and soil samples. The procedure involved the simultaneous microwave-assisted extraction of PAHs with n-hexane and the hydrolysis of samples with methanolic potassium hydroxide. Because of the complex nature of the samples, the extracts were submitted to further cleaning with silica and Florisil solid-phase extraction cartridges connected in series. Naphthalene, acenaphthene, fluorene, phenanthrene, anthracene, fluoranthene, pyrene, benz[a]anthracene, chrysene, benzo[e]pyrene, benzo[b]fluoranthene, benzo[k]fluoranthene, benzo[a]pyrene, dibenz[a,h]anthracene, benzo[g,h,i]perylene, and indeno[1,2,3-cd]pyrene, were considered in the study. Quantification limits obtained for all of these compounds (between 0.4 and 14.8 microg kg(-1) dry mass) were well below of the limits recommended in the USA and EU. Overall recovery values ranged from 60 to 100%, with most losses being due to evaporation in the solvent exchange stages of the procedure, although excellent extraction recoveries were obtained. Validation of the accuracy was carried out with BCR-088 (sewage sludge) and BCR-524 (contaminated industrial soil) reference materials.

Optimization of a microwave-assisted extraction method for the analysis of polycyclic aromatic hydrocarbons from fish samples

A microwave-assisted extraction (MAE) procedure has been developed and optimized for the extraction of six regulated polycyclic aromatic hydrocarbons (PAHs) from muscle samples of polluted fish. The procedure involves the simultaneous microwave-assisted extraction of PAHs with n-hexane and the lipids hydrolysis with potassium hydroxide. Experimental design methodology allows a quick and robust optimization of operational parameters such as the extraction time, temperature, and solvent volumes. In these final optimized conditions, the procedure can be applied to a vast range of fat containing fish samples without significant changes, thus enabling its routine use. Recoveries around 90% for the studied compounds benz[a]anthracene, benzo[b]fluoranthene, benzo[k]fluoranthene, benzo[a]pyrene, dibenz[a,h]anthracene, and indene[1,2,3-cd]pyrene and quantification limits (between 0.07 and 0.53 ng/g dry weight) far below the regulated limits, have been obtained. The procedure is applied to several different fish samples. Further, accuracy validation using NIST SRM 2977 reference material was carried out.

Simultaneous microwave-assisted extraction of polycyclic aromatic hydrocarbons, polychlorinated biphenyls, phthalate esters and nonylphenols in sediments

A new method was developed for the simultaneous extraction of polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), phthalate esters (PEs), nonylphenols (NPs) and nonylphenol mono- and diethoxylates (NP1EOs and NP2EOs, respectively) in sediment samples by means of a closed microwave system. The extractions were carried out at 21 psi and 80% of microwave power and 15 ml of acetone were used as the common extraction solvent. The filtered extract was further fractionated in two groups using Florisil ® cartridges: PAHs and PCBs were eluted with n-hexane:toluene (4:1) and the PEs, NPs and ethoxylates were eluted with ethyl acetate. All the compounds were analysed by gas chromatography–mass spectrometry (GC–MS). In case of PAHs and PCBs, the developed method was validated by comparison of the results obtained for the certified reference material NIST 1944 with the certified values. In the absence of a reference material for phthalate esters and nonylphenols, one sediment sample was extracted twice under the optimal conditions in order to check than an exhaustive extraction of the analytes occurred. This method is currently used in the study of the distribution of those organic contaminants in the estuaries of the Bay of Biscay (Spain).

Experimental design of a microwave-assisted extraction–derivatization method for the analysis of methylmercury

A simultaneous microwave-assisted extraction–derivatization procedure was developed and optimized for methylmercury analysis from biological samples. The analyte was derivatized with sodium tetraphenylborate forming a more hydrophobic compound, methylphenylmercury, which was extractable in toluene. The microwave extraction–derivatization procedure was optimized using experimental design, 2 5-1 fractional factorial. This chemometrical approach considers main effects as well as interactions of the influential parameters, indicating that temperature and its interaction with NaBPh 4 and acetic acid volumes were the variables that significantly affected methylmercury recoveries.