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1.
微波辅助萃取技术的进展   总被引:44,自引:0,他引:44  
李核  李攻科  张展霞 《分析化学》2003,31(10):1261-1268
介绍了微波辅助萃取技术的特点和装置,综述了近年来微波辅助萃取技术在环境分析和药物提取中的应用,并展望了微波辅助萃取技术的应用前景和发展方向。引用文献74篇。  相似文献   

2.
超临界流体萃取技术在中草药有效成份提取中的应用   总被引:18,自引:0,他引:18  
本文介绍了超临界流体萃取技术的基本原理、优越性以及中草药有效成分提取中的应用。  相似文献   

3.
超临界流体萃取技术在提取中药挥发油中的应用   总被引:5,自引:0,他引:5  
用超监介CO2流体萃取技术对多种中药挥发油的提取进行了综述,并将其与传统的水蒸馏法进行比较。结果表明,用超临界流体法不仅挥发油的收率高,而且提取时间也大大缩短。  相似文献   

4.
微波辅助萃取应用研究进展   总被引:5,自引:0,他引:5  
近年来关于微波辅助萃取(MAE)与其他各种样品前处理技术的结合使用,以及与多种检测技术在线联用的研究越来越多,此外离子液体等新型绿色溶剂作为萃取剂在MAE中的应用也开始得到广泛关注.本文综述了近几年微波辅助萃取在环境、天然产物提取、食品和药物分析领域的应用情况,并对其将来的发展进行了展望.  相似文献   

5.
美国应用分离公司压力溶剂提取仪利用高压、高温提高物质在溶剂中的溶解度,而提高物质在溶剂中的萃取能力。该法和传统方法相比,所需时间短(15min处理一个样品)、萃取效率高(15mL溶剂可提取10g)、且回收率高于传统的提取方法如索氏提取、超声提取等,是现代分析样品前处理的最佳选择。被美国环境保护机构EPA推荐为EPA3545标准,可广泛的应用于环境、食品、制药等领域。  相似文献   

6.
微波萃取法研究进展   总被引:86,自引:2,他引:84  
对近几年微波萃取法的研究进展及其应用进行了综述。具体介绍了微波萃取的原理、特点、萃取参数及其在环境、生化、食品、化工分析和天然产物提取等领域的应用,并从简化样品预处理步骤、开发微波萃取新技术、探讨萃取机理和改进仪器装置4个方面展望了该法的发展前景,引用文献46篇  相似文献   

7.
固相萃取新技术研究   总被引:4,自引:0,他引:4  
固相萃取技术是一种用于样品分离、纯化、浓缩的重要的样品前处理手段.近年来,高分子材料合成技术、分子印迹技术等新技术与传统固相萃取技术相结合,衍生出众多技术改进和创新.主要对各种固相萃取新技术进行评述.  相似文献   

8.
金属检测中新型前处理技术研究进展及应用   总被引:1,自引:0,他引:1  
精准检测环境和食品中金属含量对环境保护和人体健康至关重要.样品的准备环节是造成样品损失和二次污染的关键步骤, 因此合适的前处理方法可以提高金属分析的选择性和灵敏度.从液相萃取和非液相萃取新技术两方面综述了浊点萃取、离子液体、超分子溶剂-分散液液微萃取、顶空固相微萃取技术、超临界流体萃取特点及在复杂样品前处理中的应用和研究进展, 并对其未来发展方向进行了展望.  相似文献   

9.
对化学毒剂及其降解产物的分析检测是准确鉴别化学沾染的重要手段。由于化学毒剂及其降解产物的样品可能存在于各种基质中,且部分化学毒剂在水体等基质中降解速度过快,所以将痕量样品从复杂基质中快速高效的富集提取出来显得尤其重要。微萃取技术具有装置体积小、使用少量或不使用溶剂、绿色环保、易与色谱分析技术联用等突出优势受到广泛的关注,并且在含化学毒剂环境样品的前处理过程中得到大量的应用。本文介绍了基于固相和液相萃取剂的多种微萃取技术,并综述了固相微萃取和液相微萃取技术应用于化学毒剂及其降解产物检测方面的研究进展。  相似文献   

10.
离子液体是在室温或近于室温下呈液态的熔盐体系,由特定阳离子和阴离子构成。与传统的液态物质相比,离子液体几乎没有蒸气压、不易挥发、能溶解许多无机物和有机物。在样品前处理技术中得到了广泛的应用。微萃取技术是一种简便快速、提取效率高、溶剂用量少、环境友好的样品前处理技术。本文综述了离子液体在微萃取技术(液相微萃取和固相微萃取)中的应用。  相似文献   

11.
A novel infrared‐assisted extraction coupled to headspace solid‐phase microextraction followed by gas chromatography with mass spectrometry method has been developed for the rapid determination of the volatile components in tobacco. The optimal extraction conditions for maximizing the extraction efficiency were as follows: 65 μm polydimethylsiloxane‐divinylbenzene fiber, extraction time of 20 min, infrared power of 175 W, and distance between the infrared lamp and the headspace vial of 2 cm. Under the optimum conditions, 50 components were found to exist in all ten tobacco samples from different geographical origins. Compared with conventional water‐bath heating and nonheating extraction methods, the extraction efficiency of infrared‐assisted extraction was greatly improved. Furthermore, multivariate analysis including principal component analysis, hierarchical cluster analysis, and similarity analysis were performed to evaluate the chemical information of these samples and divided them into three classifications, including rich, moderate, and fresh flavors. The above‐mentioned classification results were consistent with the sensory evaluation, which was pivotal and meaningful for tobacco discrimination. As a simple, fast, cost‐effective, and highly efficient method, the infrared‐assisted extraction coupled to headspace solid‐phase microextraction technique is powerful and promising for distinguishing the geographical origins of the tobacco samples coupled to suitable chemometrics.  相似文献   

12.
样品制备与处理的进展——无溶剂萃取技术   总被引:12,自引:0,他引:12  
黄骏雄 《化学进展》1997,9(2):179-191
本文讨论了现代分析化学的重要领域之一, 样品制备及前处理技术的进展——无溶剂萃取技术。包括气相萃取、超临界流体萃取、膜萃取、固相萃取、固相微萃取等方法。简述了这些方法的原理及其应用, 探讨了样品制备与前处理技术的发展动向。  相似文献   

13.
An approach that combined green‐solvent methods of extraction with chromatographic chemical fingerprint and pattern recognition tools such as principal component analysis (PCA) was used to evaluate the quality of medicinal plants. Pressurized hot water extraction (PHWE) and microwave‐assisted extraction (MAE) were used and their extraction efficiencies to extract two bioactive compounds, namely stevioside (SV) and rebaudioside A (RA), from Stevia rebaudiana Bertoni (SB) under different cultivation conditions were compared. The proposed methods showed that SV and RA could be extracted from SB using pure water under optimized conditions. The extraction efficiency of the methods was observed to be higher or comparable to heating under reflux with water. The method precision (RSD, n = 6) was found to vary from 1.91 to 2.86% for the two different methods on different days. Compared to PHWE, MAE has higher extraction efficiency with shorter extraction time. MAE was also found to extract more chemical constituents and provide distinctive chemical fingerprints for quality control purposes. Thus, a combination of MAE with chromatographic chemical fingerprints and PCA provided a simple and rapid approach for the comparison and classification of medicinal plants from different growth conditions. Hence, the current work highlighted the importance of extraction method in chemical fingerprinting for the classification of medicinal plants from different cultivation conditions with the aid of pattern recognition tools used.  相似文献   

14.
侧柏叶中挥发性组分的酶提取及分析   总被引:1,自引:0,他引:1  
侧柏叶为柏科(Cupressaceae)植物侧柏Biota orientalis(L.)End l.的干燥嫩枝叶,侧柏别名扁柏、香柏、片柏、片松。常绿乔木,多为栽培,为我国特产[1]。侧柏叶气清香,味苦涩、微辛。具有凉血止血、清肺止咳功效,在临床上常用于治疗出血症、风湿痹痛、高血压、咳喘等,国内外学者对  相似文献   

15.
"分子模拟作为一种全新的研究手段已经在化学、化工、材料、生物等领域受到了广泛的关注。特别是在超临界流体技术方面,其应用不但可以获得许多结构、传递以及热力学信息,而且可以部分取代昂贵的超临界实验。本文从超临界流体在主体相和受限空间中的特性以及超临界萃取、反应等几个方面对现有的分子模拟方法和成果进行总结与评述,并对进一步发展的方向和面临的困难进行了讨论。  相似文献   

16.
We have developed a method for bacterial endospore detection based on the presence dipicolinic acid (dpa), a substance unique to endospores. Since the sensitivity of this technique correlates directly with the amount of dpa extracted from the spores, we examined several types of extraction techniques for their dpa extraction efficiency. The three main categories investigated are physical, germination, and chemical methods for liberation of dpa from B. subtilis endospores. Attention is concentrated on the speed, efficiency, and simplicity of the extraction techniques for optimization of endospore detection using terbium-dipicolinate photoluminescence. Although methods from all categories succeeded in extracting dpa, the technique utilizing heated dodecylamine (dda) extracted the majority of the available dpa in less than 3 min. Application of the dda extraction procedure to the terbium-dipicolinate photoluminescence method in conjunction with an increased detection capability resulted in a two-order of magnitude improvement in endospore detection. This combination of methods resulted the lowest reported limit of detection (LOD) (1000 CFU/ml) for a terbium-dipicolinate photoluminescence method in the shortest reported time (5-7 min) for the total procedure.  相似文献   

17.
《Analytical letters》2012,45(4):654-674
Jujube extract has a unique flavor that has been used as a common fragrance due to the volatile compounds. In this study, the volatiles of jujube extract were isolated by liquid–liquid extraction, simultaneous distillation extraction, ultrasound-assisted solvent extraction, and headspace solid-phase microextraction, and analyzed by gas chromatography–mass spectrometry. Altogether 92 compounds were identified by the four methods, of which 53 components were identified for the first time; however, only 21 compounds were identified by all these methods. The performance characteristics of the four pretreatment techniques were compared by principal component analysis which showed that the volatile compounds obtained by liquid–liquid extraction and ultrasound-assisted solvent extraction were similar both in categories and in content; whereas, the volatiles extracted by simultaneous distillation extraction, ultrasound-assisted solvent extraction, and headspace solid-phase microextraction greatly varied. The results indicated that a multi-pretreatment technique should be adopted in order to obtain the most complete information about the volatile compounds in jujube extract. The ultrasound-assisted solvent extraction method exhibited excellent repeatability and recoveries, and was very suitable for quantitative analysis. Although the recoveries and reproducibility of headspace solid-phase microextraction were inferior to the other methods, it was more sensitive than other methods.  相似文献   

18.
Feature extraction is essential for chemical property estimation of molecules using machine learning. Recently, graph neural networks have attracted attention for feature extraction from molecules. However, existing methods focus only on specific structural information, such as node relationship. In this paper, we propose a novel graph convolutional neural network that performs feature extraction with simultaneously considering multiple structures. Specifically, we propose feature extraction paths specialized in node, edge, and three-dimensional structures. Moreover, we propose an attention mechanism to aggregate the features extracted by the paths. The attention aggregation enables us to select useful features dynamically. The experimental results showed that the proposed method outperformed previous methods.  相似文献   

19.
Resin acids are considered to be significant contributors to the toxicity of pulp mill effluents. Traditionally, the analysis of these acids is performed by liquid–liquid extraction followed by gas chromatography. This paper describes a method suitable for monitoring the relative concentration levels of the main resin acid component, dehydroabietic acid (DHAA), in process waters by atmospheric pressure chemical ionisation-mass spectrometry (APCI-MS). This method was further improved, first by testing different precolumns for on-line sample clean-up and then by developing the APCI-MS analysis of the analytes trapped in the precolumn (i.e., solid-phase extraction column). The external standard, internal standard, and response factor methods were compared. The curve profiles of the results obtained with the above determinations were very similar to each other. This finding suggested that the rapid APCI-MS method, using a selected ion monitoring (SIM) technique, is a potential tool for monitoring relative concentration levels of DHAA. The technique is also recommended for rapid and simple monitoring of DHAA as well as of other resin acids, and their derivatives, such as their chlorinated analogues, in various aquatic environmental samples.  相似文献   

20.
In recent years, the food, pharmacy, and cosmetic industries have focused on the search of natural compounds with antimicrobial and antioxidant properties; commonly, these compounds are obtained from Kingdom plantae. The aim of the present work is comparing antibacterial and antioxidant capacity of Annona cherimola Mill leaves, using different extraction methods. The ultrasound assisted extraction technique (UAE) was compared with conventional techniques: Soxhlet and maceration. Water and ethanol were used as solvents for leaves extractions performed with these three methods. The main acetogenins reported in Annona cherimola Mill and Annona muricata L. species were simulated using the functional hybrid B3LYP and to confirm its presence, analysis of the compound composition was performed using FT-IR, UV–Vis and HPLC. Total phenolics (TP) and flavonoids (TF) were determined by spectroscopy techniques and novel Differential Pulse Voltammetry (DPV) electrochemical technique. Total Antioxidant Capacity (TAC) of the extracts was measured, using the DPPH, FRAP and CUPRAC techniques. The highest antioxidant content was found in the Soxhlet water extracts; even so, the UAE technique presented an attractive alternative due to considerable reduction in extraction time, which was greater than 99%, and possible selectivity in compounds extraction. Finally, antibacterial activity of the extracts was evaluated, obtaining the best results against gram-positive bacteria using UAE water extract. In this way, the UAE technique presents an excellent extraction option due to the considerable reduction in time and energy, as well as the increase in antibacterial activity.  相似文献   

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