微波加压溶样冷原子吸收法测定氟石粉中微量汞

本文采用美国CEM公司生产的MDS-2000型微波样品制备系统分解氟石粉样品,然后用冷原子吸收法测定氟石粉中微量汞,测定下限达0.01μg·g~(-1).一般出口合同中常规定氟石粉中含汞量小于0.3μg·g~(-1),为此采用本法完全能满足合同检验要求.微波制样系统是将微波加热技术与高压密闭溶样结合为一体,采用微处理机控制溶样过程的温度与压力.密闭容器微波消解样品,利用在2～3min内获得高温、高压分解样品,具有快速不易挥发损失等优点.     

密闭微波辅助萃取当归粉中的阿魏酸

利用密闭微波样品制备系统(具有压力控制部件),对当归中的有效成分阿魏酸的萃取进行研究,比较了密闭微波萃取同超声波萃取和索氏萃取阿魏酸提取率的差异.结果表明:微波萃取与其他两种萃取方法相比,具有速度快和萃取率高的特点.并得到了阿魏酸提取的最佳条件:微波功率为400 W,萃取剂为90%的乙醇(体积分数),固-液比为1∶15,微波辐射为240 s,当归粒径为75μm.     

密闭微波辅助萃取丹参中有效成分的研究

应用具有压力控制附件的MSP-100D密闭微波萃取装置,对丹参中的有效成分丹参酮、丹参酮A及隐丹参酮进行微波萃取研究.在乙醇体积分数为90%,微波辐射时间为4min,溶剂体积对样品质量比为20∶1和样品粒径为120目的条件下,有效成分提取率最佳.对比了密闭微波萃取同索氏萃取和超声萃取丹参有效成分的差异.     

微波萃取气相色谱法分析全血中的甲基苯丙胺

苯丙胺(又称安非他明,amphetamine)类毒品是一类非法人工合成的有机胺类兴奋剂,它主要作用于中枢神经和交感神经,属于中枢神经兴奋类毒品,其中甲基苯丙胺(俗称冰毒)最常被滥用.由于苯丙胺类毒品的滥用现象日趋严重,对社会危害极大.因此,对该类毒品的分析研究不仅意义重大,而且十分迫切.目前,国内外报道的生物样品中苯丙胺类毒品的前处理方法主要有液液萃取、固相萃取及固相微萃取等方法.近年来,微波辅助萃取(microwave-assisted extraction,MAE)因其萃取时间短、回收率高、试剂用量少、污染小和可自动控制制样条件而得到了分析工作者的认同,并已应用于土壤、沉积物中有机芳烃[1]以及生物样品中农药残留[2]的萃取研究,而在法庭科学上的应用极少报道.本文对全血中的甲基苯丙胺进行了初步的微波萃取技术研究,建立了微波萃取气相色谱法分析生物样品中甲基苯丙胺的方法.     

加速溶剂萃取-气相色谱-质谱法测定土壤中醚类杀虫剂

农药的使用,对发展现代农业起到了积极作用,但是其大量使用甚至滥用,不仅对环境造成严重的污染,同时对人体健康造成危害,因此,对农药进行分析和检测十分必要[1]。固相基质(土壤等)的萃取方法主要有索氏提取[2]、超声辅助萃取[3]、微波辅助萃取[4]、超临界萃取[5]和加速溶剂萃取[6]等。加速溶剂萃取是在较高温度(50℃~200℃)、较高压力(6.89~20.68MPa)下对样品进行萃取,溶剂用量     

电感耦合等离子体原子发射光谱法测定黄连中铁、镁、锌含量

<正>样品基体对元素测定的准确性产生重要影响,特别是中药样品。目前,中药中很多成分还未被研究,因其基体成分非常复杂,需进行样品前处理。消化处理是元素分析中一种常用的样品前处理方法,即消解样品中的有机物。由于有些待测元素以化合物的形式存在于中药材中,需要破坏有机物的价键结构,从而释放出被结合的待测元素。已见报道的消化处理方法主要有湿法消化[1]、微波消化[2-3]、干法灰化[4]和密闭压力罐法[5],其中干法灰化、湿法消     

玻璃容器对水中铝测定的影响

铝的过量摄入是老年人患痴呆症的危险因素[1]之一.在饮用水、矿泉水、涉水管材中,铝含量是必检指标,其检测方法有铬天青S分光光度法、铝试剂分光光度法[2]、电感耦合等离子体发射光谱法[3]等,分析结果的准确性受样品采集(容器选择、样品运输保存),样品分析(标准溶液、仪器稳定性、实验室质量控制)及数据处理的影响.一般的玻璃容器在贮存水样时会溶出钠、钙、镁、硅、硼等元素,有的化学玻璃Al2O3含量达2.2%～2.4%[4].     

超声-微波协同萃取装置用于土壤中多环芳烃的分析

本研究将开放式微波和直接超声波振荡两种不同的能量方式相结合,研制出超声-微波协同萃取装置。通过萃取土壤中微量多环芳烃(PAHs),对方法和仪器的可行性进行了初步评价。结果表明,在60 mL二氯甲烷-正已烷(1∶1,V/V)的混合萃取剂,100 W微波辐射功率(超声振动功率固定为50 W),萃取9~10m in,土壤中多环芳烃回收率达86.6%,相对标准偏差约4.0%。与索氏抽提、高压密闭和开放式微波等萃取方法相比,本方法具有样品容量大,萃取时间短,萃取效率受样品中含水量和溶剂极性影响小等优点。     

用于固相微萃取的乙烯基开链冠醚复合涂层的研制

固相微萃取 (SPME)是一种新型的样品预处理技术 [1] ,其核心是 SPME装置中萃取头上的固相涂层 .目前商用 SPME涂层的种类较少 ,热稳定性较差 (推荐使用温度 2 0 0～ 2 80℃ ) ,使用寿命较短(40～ 1 0 0次 ) ,价格偏高 ,限制了其推广应用 .因此发展高选择性、高稳定性和高效的固     

密闭系统中微波辅助萃取机制探讨

通过与普通加热萃取虎杖中白藜芦醇的产率进行对比 ,对密闭系统中微波辅助萃取的机理进行了探讨。结果表明 ,微波辅助萃取与普通加热萃取二者的活化能相差不大 ,分别为30.06和30.32kJ·mol-1。但微波辅助萃取的表观速率常数约是普通加热萃取的20倍。并且还利用电子扫描显微镜对样品微结构进行了观察 ,研究表明 ,细胞内极性成分如水吸收了微波能后压力迅速增加导致细胞结构的破坏是MAE快速高效的关键 ,由于细胞的破坏 ,萃取剂和萃取目标化合物更容易通过细胞壁 ,加速了扩散速度 ,进而加速了萃取速度。     

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.     

Microwave-assisted extraction of phenolics from Canarium album L. and identification of the main phenolic compound

Microwave-assisted extraction (MAE) was applied in the extraction of phenolics from Canarium album L. Effects of various conditions including the solvent, solvent to material ratio, microwave power and irradiation time on extraction yield of phenolics were investigated. In terms of the optimal conditions of MAE, it was concluded that 70% (v/v) of ethanol was the proper extraction solvent, the solvent to material ratio was 10 : 1 (mL : g), and the microwave power and irradiation time were 600 W and 15 s, respectively. Compared with normal stirring extraction and ultrasound-assisted extraction, the MAE of phenolics from C. album L. was more time efficient and gave a high extraction rate. More than 1.2% extraction yield was achieved with MAE, and the purity of the phenolics in the extract product was up to 25%. In addition, by ultraviolet-visible (UV) spectrometry and electrospray ionised mass spectrometry (ESI/MS), the main phenolic compound in the extract product was identified as gallic acid.     

Orthogonal test design for optimisation of extraction of trans-resveratrol from Pinot Noir-grape pomace

Yield of trans-resveratrol from Pinot Noir-grape pomace obtained by microwave-assisted extraction (MAE) through an orthogonal experiment (16 (4(4))) was investigated to get the best extraction conditions. In this method, the highest yield was obtained when the extraction solvent used ethanol; the ratio of raw material to solvent, the extraction time, the extraction temperature and microwave irradiation power were 1:20 (g mL(-1)), 30 min, 55°C and 1.0 kW, respectively. The average yield of trans-resveratrol was 90.87%, and the recovery was in the range of 85.49-89.04% with relative standard deviation lower than 1.39%. Then, the extract of MAE was separated by NKA-9 macroporous resin and re-crystallisation. Finally, the purity of trans-resveratrol was 97.47%.     

Application of factorial design and Box-Behnken matrix in the optimisation of a microwave-assisted extraction of essential oils from Salvia mirzayanii

Essential oil of Salvia mirzayanii cultivated in Iran was obtained by microwave assisted extraction (MAE) procedures. The essential oil was analysed by capillary gas chromatography using flame ionisation and mass spectrometric detections. The effects of different parameters, such as microwave power, temperature, time and type of solvent on the MAE of Salvia mirzayanii oil were investigated. Results of the two-level fractional factorial design (2(4-1)) based on an analysis of variance demonstrated that only the power, temperature and type of solvent were statistically significant. Optimal conditions for the extraction of essential oils were obtained by using Box-Behnken design. For optimum recovery of essential oil the variables power, temperature and solvent values were 115?W, 50°C and 14?s, respectively. Under the optimised experimental conditions, the extraction yield of microwave assisted extraction was 11.2% (w/w).     

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.     

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.     

Dynamic Microwave-assisted Extraction of Flavonoids from Radix Scutellariae

IntroductionRadix Scutellariaeis the root ofScutellaria bai-calensis Georgi(Labiatae), which is widely cultivatedand used as traditional Chinese medicine. It has beendemonstrated to be anti-inflammatory, anti-metamor-phic, antiviral, anti-hot, and live pr…     

Optimization of microwave‐assisted extraction of protopine and allocryptopine from stems of Macleaya cordata (Willd) R. Br. using response surface methodology

The purpose of the research was to investigate the multiple response optimizations for the extraction of protopine and allocryptopine from the stems of Macleaya cordata (Willd) R. Br. by using microwave‐assisted extraction (MAE). A three‐level, three‐factor Box–Behnken design of response surface methodology was used to develop response model, and desirability function was employed to optimize the effects of main extraction parameters. Three variables, ethanol concentration (20–80%, v/v), extraction temperature (30–70°C) and solvent/solid ratio (10:1 to 30:1, mL/g), were investigated in this study. The results showed that the optimum parameters of MAE were ethanol concentration of 45.2 % (v/v), extraction temperature of 54.7°C and solvent/solid ratio of 20.4:1 (mL/g). Under these conditions, the extraction yields of protopine and allocryptopine were 89.4 and 102.0%, respectively, and the extracta sicca yield was 12.5%. The combination use of response surface methodology, Box‐Behnken design and the appropriate desirability function could provide an insight into a lab‐scale MAE process, and help to develop procedures for commercial production of active ingredients from medical plants.     

微波萃取技术

介绍了在气相／液相色谱测定前的一种新的样品制备技术——微波萃取技术及其所使用的试剂、设备和条件。通过一些数据以及与Ｓｏｘｈｌｅｔ法、超声萃取法比较说明,微波萃取是一种快速、试剂用量少、回收率高、灵敏以及易于自动控制的方法。     

Microwave-assisted extraction of oxymatrine from Sophora flavescens

In this paper, microwave-assisted extraction (MAE) of oxymatrine from Sophora flavescens were studied by HPLC-photodiode array detection. Effects of several experimental parameters, such as concentration of extraction solvent, ratio of liquid to material, microwave power, extraction temperature, and extraction time on the extraction efficiencies of oxymatrine were evaluated. The optimal extraction conditions were 60% ethanol, a 20:1 (v/v) ratio of liquid to material and extraction for 10 min at 50 °C under 500 W microwave irradiation. Under the optimum conditions, the yield of oxymatrine was 14.37 mg/g. The crude extract obtained could be used as either a component of some complex traditional medicines or for further isolation and purification of bioactive compounds. The results, which indicated that MAE is a very useful tool for the extraction of important phytochemicals from plant materials, should prove helpful for the full utilization of Sophora flavescens.