Microwave-Assisted Solvent Extraction of Melamine from Seafood and Determination by Gas Chromatography–Mass Spectrometry: Optimization by Factorial Design

Melamine attracts considerable attention because of its toxicity. The determination of melamine in seafood was performed by gas-chromatography–mass spectrometry, using an optimized version of a method adopted by the U.S. Food and Drug Administration. The melamine was extracted by closed-vessel microwave-assisted solvent extraction (MAE), as a valid alternative in sample preparation, to reduce analysis time and provide less ambiguous data. The procedure was optimized by means of experimental factorial design considering the three main variables that affect this process: microwave oven power, the maximum temperature inside the extraction tube, and the hold time. The recovery of melamine in spiked samples was used as the elemental response value of the design. Temperature and hold time had a more positive effect on the response than the microwave power. A significant positive interaction was observed between oven power and hold time. A temperature of 70°C and a hold time of 1 min gave a recovery of 92 ± 5% for a microwave power of 600 W. Under these conditions, the total microwave extraction time was approximately 2 minutes, a much shorter time compared to the ultrasonic bath, which required a total time of 40 min. The repeatability of the method was approximately 3%. The limits of quantification were 0.55 mg kg^?1 for MAE and 1.9 mg kg^?1 for the ultrasonic bath; the linearity was confirmed up to 10 mg kg^?1. In conclusion, the MAE procedure was shown to be an excellent alternative to the official method.     

Evaluation of microwave-assisted extraction for aristolochic acid from Aristolochiae Fructus by chromatographic analysis coupled with nephrotoxicity studies

In this paper, a microwave-assisted extraction (MAE) method was established for aristolochic acid-I from Aristolochiae Fructus, and the advantage of MAE was evaluated by chromatographic analysis coupled with nephrotoxicity studies. The experimental parameters of MAE for aristolochic acid-I in Aristolochiae Fructus were investigated and MAE was compared with Soxhlet extraction and ultrasound-assisted extraction in terms of extraction yields and extraction conditions. Under the optimum conditions, MAE could provide higher extraction yields of aristolochic acid-I (1.10 mg/g) than ultrasound-assisted extraction (0.82 mg/g) and Soxhlet extraction (0.95 mg/g), in addition to using less solvent and having a shorter extraction time. Furthermore, the nephrotoxicities of the extracts of Aristolochiae Fructus from different extraction procedures were investigated in Sprague-Dawley rats. The results of nephrotoxicity studies of, for example, general conditions, biochemistry parameters and histopathology examination showed no significantly differences in the nephrotoxicity levels of the extracts from MAE and that from Soxhlet extraction. These results indicated that MAE technique is a simple, rapid and effective extraction method, and the microwave irradiation during MAE procedure did not have any influence on the nephrotoxicity of Aristolochiae Fructus compared with Soxhlet extraction.     

微波法提取水蓼中总黄酮的工艺研究

研究了水蓼中总黄酮的微波提取最佳工艺。采用单因素试验和正交试验考察微波功率、乙醇浓度、微波辐射时间、料液比对水蓼中总黄酮提取率的影响,优选提取工艺。最佳工艺条件为:微波功率为520W,乙醇浓度为60%,微波辐射60s,间歇辐射3次,料液比为1g∶20mL。结果表明,微波提取具有提取率高、提取速度快等特点,用于中草药的提取应用前景广阔。     

Determination of parabens and endocrine-disrupting alkylphenols in soil by gas chromatography–mass spectrometry following matrix solid-phase dispersion or in-column microwave-assisted extraction: a comparative study

Two rapid methods were evaluated for the simultaneous extraction of seven parabens and two alkylphenols from soil based on matrix solid-phase dispersion (MSPD) and microwave-assisted extraction (MAE). Soil extracts were derivatized with N,O-bis(trimethylsilyl)trifluoroacetamide and analyzed by gas chromatography with mass spectrometry. Extraction and clean-up of samples were carried out by both methods in a single step. A glass sample holder, inside the microwave cell, was used in MAE to allow the simultaneous extraction and clean-up of samples and shorten the MAE procedure. The detection limits achieved by MSPD were lower than those obtained by MAE because the presence of matrix interferences increased with this extraction method. The extraction yields obtained by MSPD and MAE for three different types of soils were compared. Both procedures showed good recoveries and sensitivity for the determination of parabens and alkylphenols in two of the soils assayed, however, only MSPD yielded good recoveries with the other soil. Finally, MSPD was applied to the analysis of soils collected in different sites of Spain. In most of the samples analyzed, methylparaben and butylparaben were detected at levels ranging from 1.21 to 8.04 ng g⁻¹ dry weight and 0.48 to 1.02 ng g⁻¹ dry weight, respectively.     

微波辅助萃取新鲜芦荟叶中芦荟甙的研究

应用密闭微波萃取装置对芦荟中的有效成分芦荟甙进行了微波萃取研究,并利用透射电子显微镜对微波萃取机理进行了初步探讨.讨论了不同萃取剂、溶剂浓度、萃取时间和微波功率等对提取率的影响.在萃取剂为乙醇-水体系,溶剂(乙醇)体积分数为70%、萃取时间为4min及微波功率为340W的条件下,萃取效果最佳.与索氏提取及超声波萃取法相比,本法具有萃取速度快、提取率高及溶剂用量少等特点.     

Optimization and comparison of MAE, ASE and Soxhlet extraction for the determination of HCH isomers in soil samples

The microwave-assisted extraction (MAE), accelerated solvent extraction (ASE) and Soxhlet extraction of two isomers of hexachlorocyclohexane, alpha-HCH and gamma-HCH, from a polluted landfill soil have been optimized following different experimental designs. In the case of microwave-assisted extraction, the following variables were considered: pressure, extraction time, microwave power, percentage of acetone in n-hexane mixture and solvent volume. When ASE extraction was studied the variables were pressure, temperature and extraction time. Finally, the percentage of acetone in n-hexane mixture and the extraction time were the only variables studied for Soxhlet extraction. The concentrations obtained by the three extraction techniques were, within their experimental uncertainties, in good agreement. This fact assures the possibility of using both ASE and MAE techniques in the routine determination of lindane in polluted soils and sediments.     

微波辅助萃取鬼箭羽叶中芦丁和槲皮素

建立了鬼箭羽中主要有效成分芦丁和槲皮素的MAE-HPLC定量分析方法, 该方法具有测定准确、操作简便和分析速度快等优点. 此外, 利用扫描电镜观察了鬼箭羽叶经微波辅助萃取后植物结构的变化, 初步证明了微波辅助萃取鬼箭羽叶的萃取机理符合细胞破壁学说.     

Comparison of techniques for the extraction of the anti-cancer drug camptothecin from Nothapodytes foetida

Extraction methods using stirring extraction, Soxhlet extraction, ultrasonic extraction and microwave-assisted extraction (MAE) were evaluated for the percentage extraction of camptothecin (CPT) and 9-methoxycamptothecin (9-Me-CPT) from Nothapodytes foetida. The extracts were analyzed by high performance liquid chromatography (HPLC). Methanol (90%, v/v) extracted high percentage extraction of CPT and 9-Me-CPT compared to ethanol (90%, v/v). The results shows that the percentage extraction of CPT and 9-Me-CPT from N. foetida by MAE was more efficient in short time followed by Soxhlet extraction, ultrasonic and stirring extraction methods. Maximum percentage extraction of CPT (2.67%, w/w) was obtained by MAE technique. MAE has need of 3 min, whereas ultrasonic extraction, Soxhlet extraction and stirring extraction techniques require 30, 120 and 30 min, respectively to leach higher percentage extraction of CPT and 9-Me-CPT. The times taken by the microwave extraction process was 40 times less than the Soxhlet extraction for percentage extraction of alkaloids. The present results show that the extraction efficiency and considerable saving of time by MAE was more competent than the other extraction techniques.     

一种新型微波辅助萃取法用于中药刺五加中总黄酮萃取的研究

微波萃取法是目前世界上公认的绿色样品预处理技术之一 .它在环境、生化、食品、工业以及天然产物和中药等领域均有广泛的应用 [1～ 4 ] .目前 ,最常用的微波萃取系统有两种 [5] ,一种是使用多模式微波炉 ,在密闭容器中加热样品及有机溶剂 ,将目的组分从样品基体中萃取出来 .由于在密闭容器中 ,被萃取样品和溶剂处于高压下 ,温度很高 ,使待萃取物的溶解度增大 ,可获得更高的萃取率 .同时 ,用于这种微波萃取的系统一般可同时容纳 9～ 1 2个萃取罐 ,使试样的批量处理能力大大提高 .该法最主要的缺点是萃取后的液体一般需经离心分离或微孔玻璃…     

Microwave-assisted extractions of active ingredients from plants

Microwave-assisted extraction (MAE) is widely employed in the analysis and the extraction of active compounds from plants. This review summarizes the research done during the last decade on the MAE of active ingredients from plants. Advances and modifications to improve the performance of MAE are presented and discussed in detail. Modified MAE such as vacuum microwave-assisted extraction (VMAE), nitrogen-protected microwave-assisted extraction (NPMAE), ultrasonic microwave-assisted extraction (UMAE), dynamic microwave-assisted extraction (DMAE) and other advancements in MAE are also detailed in this article. In addition, the microwave extraction procedures and the important parameters influencing its performance are also included, together with the advantages and the drawbacks of each MAE techniques.     

微波辅助流动萃取槐花中的黄酮类成分

槐花为豆科落叶乔木槐树(Sophora japonica L.)的花蕾,槐花能降低血管的通透性,所含芸香甙(芦丁)对心脏传导系统有抑制作用,能增强收缩力及输出量,降低血压;所含槲皮素可以扩张冠状动脉,降低心肌耗氧量,并能降低血脂。     

微波辅助提取石蒜和虎杖中有效成分的动力学模型

基于微波辅助提取(MAE)中药材中化学成分的非稳态扩散过程, 根据Fick第二定律建立了石蒜中石蒜碱、力可拉敏和加兰他敏以及虎杖中白藜芦醇和大黄素微波辅助提取过程的动力学模型. 研究了提取时间、提取温度及药材粒度等因素对石蒜中石蒜碱、力可拉敏和加兰他敏以及虎杖中大黄素和白藜芦醇的提取率的影响, 采用Matlab软件编程对动力学模型进行回归分析, 拟合的动力学模型与实验结果吻合. 根据模型计算了石蒜中石蒜碱、力可拉敏和加兰他敏以及虎杖中大黄素和白藜芦醇在MAE提取过程中的扩散系数D, 与溶剂加热回流法(SRE)比较, 引入增强因子γ, 表征了微波对溶质分子扩散传质的影响及其对不同基质药材作用的差异.     

Microwave-assisted extraction of solanesol from tobacco leaves

Solanesol is the starting material for many high-value biochemicals, including co-enzyme Q10 and Vitamin K analogues. In the present study, a microwave-assisted extraction (MAE) technique has been developed for the fast extraction of solanesol from tobacco leaves. Compared to heat-reflux extraction, MAE reduced extraction time and obtained higher percentage extracted of solanesol. The effect of microwave on cell destruction of plant material was observed by scanning electron microscopy (SEM). The microwave-assisted extraction efficiency was further improved by adding NaOH into the extraction solvent, and the maximum percentage extracted of solanesol reached 0.91% (weight solanesol/weight tobacco) in 40 min at an optimum NaOH concentration of 0.05 M. The developed MAE integrated with saponification process provided an efficient method for solanesol recovery from tobacco leaf materials, and it also alleviated emulsification in the following separation and purification procedure as well.     

Optimisation of a microwave-assisted extraction method for the simultaneous determination of haloanisoles and halophenols in cork stoppers

This study presents a method based on the use of microwave-assisted extraction (MAE) for the quantitative analysis of 2,4,6-trichloroanisole (TCA), 2,3,4,6-tetrachloroanisole (TeCA), pentachloroanisole (PCA), 2,4,6-tribromoanisole (TBA), 2,4,6-trichlorophenol (TCP), 2,3,4,6-tetrachlorophenol (TeCP), pentachlorophenol (PCP) and 2,4,6-tribromophenol (TBP) in cork stoppers. The influential parameters of the MAE procedure (extraction time, temperature and solvent volume) were optimised using a central composite experimental design combined with desirability functions. The optimal conditions identified were temperature 170 degrees C, solvent volume 35 mL and extraction time 90 min. MAE extracts were concentrated and derivatised prior to separation and quantification by gas chromatography with electron capture detection. To evaluate the applicability of the proposed MAE method, recovery results were compared with those obtained with the Soxhlet extraction method; the results were similar with both extraction methods. The new method was also satisfactorily applied to real cork stopper samples.     

High-throughput dynamic microwave-assisted extraction on-line coupled with solid-phase extraction for analysis of nicotine in mushroom

A simple and low-cost high-throughput dynamic microwave-assisted extraction (HTDMAE) device was firstly assembled and validated by the extraction of nicotine in mushroom samples. In this device, a household microwave oven was applied to provide the microwave energy; a vacuum pump was used to deliver the solvent. Compared with traditional dynamic microwave-assisted extraction method, the sample throughput and microwave energy utilization were improved by the HTDMAE, up to 20 samples could be treated simultaneously in 9 min. Taking extraction of nicotine in mushroom sample as an example, a method was established with extraction, separation and enrichment of nicotine in a single step by the device on-line coupled with solid-phase extraction (SPE). Nicotine was first extracted from the mushroom samples with water under the action of microwave energy, and then directly introduced into the SPE column which was packed with cation-exchange resins. Subsequently, the nicotine trapped on the resins was eluted with methanol-ammonia (95:5, v/v) and determined by high-performance liquid chromatography. The limit of detection of nicotine obtained is 5.6 μg kg(-1) in fresh mushroom sample. The recovery of nicotine in mushroom samples is in the range of 87.4-104.0%. The proposed method which significantly reduced the overall analysis time and increased sample throughput should be favored for routine analyse of complex solid sample.     

An efficient microwave assisted extraction of phenolic compounds and antioxidant potential of Ginkgo biloba

Flavonoid glycosides are a significant group of compounds found in Ginkgo biloba leaves, but the long extraction procedures in existing methods are a challenging problem. In this work, a microwave-assisted extraction (MAE) method has been developed for extracting bioactive compounds from G. biloba. Several variables were optimized, such as extracting solvent, microwave power, and extraction time that can potentially affect the extraction yield. The total phenolic content, antioxidant activity (using DPPH, ABTS and FRAP assays) and flavonoid glycosides of different extracts using RP-HPLC were assessed. The antioxidant capacity was found to be highest with MAE using 60% aq. ethanol as extracting solvent and microwave power of 120W for 20 min.     

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.     

Optimization and comparison of MAE, ASE and Soxhlet extraction for the determination of HCH isomers in soil samples

The microwave-assisted extraction (MAE), accelerated solvent extraction (ASE) and Soxhlet extraction of two isomers of hexachlorocyclohexane, α-HCH and γ-HCH, from a polluted landfill soil have been optimized following different experimental designs. In the case of microwave-assisted extraction, the following variables were considered: pressure, extraction time, microwave power, percentage of acetone in n-hexane mixture and solvent volume. When ASE extraction was studied the variables were pressure, temperature and extraction time. Finally, the percentage of acetone in n-hexane mixture and the extraction time were the only variables studied for Soxhlet extraction. The concentrations obtained by the three extraction techniques were, within their experimental uncertainties, in good agreement. This fact assures the possibility of using both ASE and MAE techniques in the routine determination of lindane in polluted soils and sediments. Received: 28 January 2000 / Revised: 28 March 2000 / Accepted: 31 March 2000     

紫草中活性成分的非极性溶剂动态微波提取及高效液相色谱法测定

用非极性溶剂动态微波辅助提取,高效液相色谱法测定紫草中的紫草素和β,β′-二甲基丙烯酰紫草素.考察了微波吸收介质类型、提取溶剂种类、提取溶剂流速、微波功率和样品粒度对提取产率的影响,优化提取参数.在优化条件下,将所建立的方法与超声提取和索氏提取相比,所得紫草素和β,β′-二甲基丙烯酰紫草素的产率相差不大,但本文所建立的方法所需提取时间短(5min)、溶剂消耗少(10mL).与极性溶剂动态微波辅助提取相比,提取产率大幅度提高.结果说明,所建立的方法是一种有效的提取中草药中一些活性成分的方法,特别是对于一些在非极性溶剂中有更高溶解度的化合物,此方法更具优势.     

微波萃取土壤中PAHs的研究

研究了MK-1型光纤压力自控微波溶样系统用于微波萃取的可行性.以合成土样为对象,比较系统地研究了微波萃取PAHs的条件、萃取效率以及溶剂、水分、土壤基体物质等因素的影响.在微波作用下丙酮-正已烷(体积比为1:1)和二氯甲烷对PAHs的萃取能力相近;试样中小于20%的水分使丙酮-正己烷(体积比为1:1)的萃取能力提高,而水分高于5%则使二氯甲烷的萃取能力略有降低.在选定条件下,萘、苊烯、芴、菲、蒽、(出)、苯并(a)芘的回收率在82.2%～94.1%之间.