Determination of three capsaicinoids in Capsicum annuum by pressurized liquid extraction combined with LC‐MS/MS

A new method based on pressurized liquid extraction followed by LC‐MS/MS analysis has been developed for the identification and quantification of three capsaicinoids (capsaicin, dihydrocapsaicin, and nordihydrocapsaicin) in extracts of Capsicum annuum. For the recovery of three capsaicinoids, the efficiency levels of ultrasonic‐assisted extraction, microwave‐assisted extraction, Soxhlet extraction, and pressurized liquid extraction were compared under different conditions. Pressurized liquid extraction resulted in higher yields. Pressurized liquid extractions were performed using methanol; temperature was set at 100°C and pressure at 1500 psi. LC analysis was performed on a Waters XBridge? C₁₈ column (150 × 2.1 mm, id 3.5 μm) eluted by a mobile phase of 0.1% formic acid and ACN. Data acquisition was carried out in multiple reaction monitoring transitions mode, monitoring two‐reaction monitoring transitions to ensure an accurate identification of target compounds in the samples. The proposed method is rapid, simple, and could be utilized for the routine analysis of three capsaicinoids in C. annuum samples.     

Application of ionic liquid‐based surfactants in the microwave‐assisted extraction for the determination of four main phloroglucinols from Dryopteris fragrans

An ionic liquid‐based surfactant combined with microwave‐assisted extraction method, followed by RP‐HPLC‐diode array detection (DAD) with a core shell column, was successfully applied in extracting and quantifying four major phloroglucinols from Dryopteris fragrans. Eight ionic liquids with different cation and anion were investigated, and 1‐octyl‐3‐methylimidazolium bromide presented the best relative extraction efficiency for four phloroglucinols. The optimum conditions of this method were as follows: ionic liquid concentration 0.75 M, liquid/solid ratio 12:1 mL/g, extraction time 7 min, extraction temperature 50°C, and irradiation power 600 W. The quality analytical parameters of the method were obtained based on the linearity, precision, accuracy, detection, and quantification limits. The recoveries were between 96.90 and 103.5% with standard deviations not higher than 4.7%. Compared with ionic liquid‐based heat reflux extraction, ultrasonic‐assisted extraction, negative‐pressure cavitation extraction, and conventional microwave‐assisted extraction, the relative extraction efficiencies of the proposed method for four phloroglucinols increased 1.5–40.4%. The method was successfully applied for the quantification of four major phloroglucinols from D. fragrans. All these results suggest that the developed method represents an excellent alternative for the extraction and quantification of phloroglucinols in other plant materials.     

Rapid and cost‐effective method for the simultaneous quantification of seven alkaloids in Corydalis decumbens by microwave‐assisted extraction and capillary electrophoresis

A rapid and cost‐effective method based on microwave‐assisted extraction followed by capillary electrophoresis was developed for simultaneous quantification of seven alkaloids in Corydalis decumbens for the first time. The main parameters affecting microwave‐assisted extraction and capillary electrophoresis separation were investigated and optimized. The optimal microwave‐assisted extraction was performed at 40°C for 5 min using methanol/water (90:10, v/v) as the extracting solvent. Electrophoretic separation was achieved within 15 min using an uncoated fused‐silica capillary (50 μm internal diameter and 27.7 cm effective length) and a 500 mM Tris buffer containing 45% v/v methanol (titrated to pH^* 2.86 with H₃PO₄). The developed method was successfully applied to the quantification of seven alkaloids in Corydalis decumbens obtained from different regions of China. The combination of microwave‐assisted extraction with capillary electrophoresis was an effective method for the rapid analysis of the alkaloids in Corydalis decumbens .     

Microwave‐assisted extraction versus Soxhlet extraction to determine triterpene acids in olive skins

Microwave‐assisted extraction is compared with a more classical technique, Soxhlet extraction, to determine the content of triterpene acids in olive skins. The samples used in their original unmilled state and milled were extracted with ethyl acetate or methanol as solvents. The optimized operating conditions (e.g., amount and type of solvent, and time and temperature of extractions) to attain the better extraction yields have been established. For the identification and quantitation of the target compounds, an ultra high performance liquid chromatography with tandem mass spectrometry method was employed. The best results were achieved using the microwave‐assisted extraction technique, which was much faster than the Soxhlet extraction method, and showed higher efficiency in the extraction of the triterpenic acids (oleanolic and maslinic).     

Determination of hexabromocyclododecane diastereoisomers in Sargassum fusiforme and comparison of the extraction efficiency of ultrasonication, microwave-assisted extraction, Soxhlet extraction and pressurised liquid extraction

The concentrations of hexabromocyclododecanes (HBCD) in Sargassum fusiforme, the common Chinese edible seaweed, were investigated by LC‐MS/MS. For the recovery of HBCD, the efficiency levels of ultrasonic‐assisted extraction, microwave‐assisted extraction, Soxhlet extraction and pressurised liquid extraction were compared under different conditions. Pressurised liquid extraction and ultrasonic‐assisted extraction resulted in complete extraction of HBCD (92.7–102.5% recovery). Microwave‐assisted extraction and Soxhlet extraction, on the other hand, offered relatively low extraction recoveries (82.1–90.6%). The instrumental LODs on columns in this study were 1.0, 0.3 and 0.7 ng/g for α‐HBCD, β‐HBCD and γ‐HBCD, respectively. Because of its accuracy, this straightforward method is particularly suitable for routine HBCD analysis.     

Green approach to the extraction of major capsaicinoids from habanero pepper using near-infrared,microwave, ultrasound and Soxhlet methods,a comparative study

A simple method for the extraction of two major capsaicinoids from habanero peppers, using near-infrared irradiation, microwave irradiation or ultrasound as the energy source and ethanol as the solvent, was compared with Soxhlet extraction. The extraction processes were monitored by gas chromatography/mass spectrometry. The new processes offer better overall yields and a higher ratio of capsaicin to dihydrocapsaicin than Soxhlet extraction. The physical effect of the different energy sources on the peppers was determined using scanning electron microscopy. Extraction of capsaicin and dihydrocapsaicin using near-infrared irradiation, which has not been previously reported, was shown to be a simple and efficient alternative extraction procedure.     

Extraction of polycyclic aromatic hydrocarbons and organochlorine pesticides from soils: a comparison between Soxhlet extraction, microwave-assisted extraction and accelerated solvent extraction techniques

The methods of simultaneous extraction of polycyclic aromatic hydrocarbons (PAHs) and organochlorine pesticides (OCPs) from soils using Soxhlet extraction, microwave-assisted extraction (MAE) and accelerated solvent extraction (ASE) were established, and the extraction efficiencies using the three methods were systemically compared from procedural blank, limits of detection and quantification, method recovery and reproducibility, method chromatogram and other factors. In addition, soils with different total organic carbon contents were used to test the extraction efficiencies of the three methods. The results showed that the values obtained in this study were comparable with the values reported by other studies. In some respects such as method recovery and reproducibility, there were no significant differences among the three methods for the extraction of PAHs and OCPs. In some respects such as procedural blank and limits of detection and quantification, there were significant differences among the three methods. Overall, ASE had the best extraction efficiency compared to MAE and Soxhlet extraction, and the extraction efficiencies of MAE and Soxhlet extraction were comparable to each other depending on the property such as TOC content of the studied soil. Considering other factors such as solvent consumption and extraction time, ASE and MAE are preferable to Soxhlet extraction.     

Application of microwave heating for the fast extraction of fat content from the poultry feeds

A rapid method has been developed to extract and quantitatively measure the total oil content in poultry feeds using a domestic microwave oven. The optimized extraction procedure involves the replicate (6×) extraction of 5 g of ground feed with 12 ml of hexane for 20 s in a 900 W oven. Each replicate involves the collection of the resulting miscella and its replacement with fresh solvent for re-extraction. The collected extracts were centrifuged and transferred to a vial. The solvent was evaporated to a constant weight and the residual lipid weighed. In comparison to conventional Soxhlet extraction method, lipid contents obtained using the optimized microwave procedure was not significantly different. However, FTIR analysis indicated that the microwave procedure was superior in minimizing the formation of free fatty acids (FFA) relative to the Soxhlet procedure if the temperature of the sample was kept within the range of 45–50 °C. This simple, sequential extraction procedure is rapid, highly efficient and provides a simple mean of quantitating the lipid content of poultry feed in less than 40 min without the need for specialized microwave oven.     

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。     

Microwave‐assisted extraction and rapid isolation of ursolic acid from the leaves of Eucalyptus × hybrida Maiden and its quantification using HPLC‐diode array technique

Ursolic acid (UA) is the most important bioactive phytoconstituent of Eucalyptus × hybrida Maiden leaves and exhibits anticancer, antimutagenic, anti‐inflammatory, antioxidative, and antiprotozoal activities. In this study, microwave‐assisted extraction technique was employed for rapid isolation of UA from the leaves of Eucalyptus × hybrida and simultaneously HPLC‐diode array method was developed for the quantification of UA. Effects of several experimental parameters on the extraction efficiencies of UA, such as type and volume of extraction solvents, microwave power and extraction time, were evaluated. The optimal extraction conditions were found to be 20 mL of a mixture of chloroform/methanol, 60:40; liquid‐to‐material ratio, 4:1; preleaching time, 10 min; microwave power, 600 W; temperature, 50°C; and microwave irradiation time, 5 min. Under the optimum conditions, the yield of UA was found to be 1.95 ± 0.08% in the dry leaves of Eucalyptus × hybrida. The results showed that microwave‐assisted extraction is a more rapid extraction method with higher yield and lower solvent consumptions than the conventional method. It is a faster, convenient, and appropriate method and it may be used for rapid isolation and quantification of UA and other important phytoconstituents present in the leaves of Eucalyptus × hybrida.     

中药刺五加叶中有效成分的几种微波辅助提取方法研究

利用高压微波提取法、常压回流微波提取法、流动微波提取法和索氏提取法提取中药刺五加中黄酮和皂苷类化合物,考察各种提取方法提取效率随时间的变化。结果表明,高压微波提取法在压力为300kPa,完全提取的时间为10min;常压回流微波提取法完全提取的时间为14min;流动微波提取法完全提取的时间为10min;索氏提取法需8h尚能完成。各种提取方法总黄酮的提取率分别为43．7、48．2、42．7和34．7mg／g;总皂苷的提取效率分别为60．2、61．5、59．8和46．5mg/g。与索氏提取法比较,微波提取法提取黄酮和皂苷,提取时间大大缩短,且提取效率显著提高。     

Ionic liquid‐based microwave‐assisted extraction for the determination of flavonoid glycosides in pigeon pea leaves by high‐performance liquid chromatography‐diode array detector with pentafluorophenyl column

In this study, an ionic liquid‐based microwave‐assisted extraction (ILMAE) followed by high‐performance liquid chromatograph y ‐diode array detector with a pentafluorophenyl column for the extraction and quantification of eight flavonoid glycosides in pigeon pea leaves is described. Compared with conventional extraction methods, ILMAE is a more effective and environment friendly method for the extraction of nature compounds from herbal plants. Nine different types of ionic liquids with different cations and anions were investigated. The results suggested that varying the anion and cation had significant effects on the extraction of flavonoid glycosides, and 1.0 M 1‐butyl‐3‐methylimidazolium bromide ([C4MIM]Br) solution was selected as solvent. In addition, the extraction procedures were also optimized using a series of single‐factor experiments. The optimum parameters were obtained as follows: extraction temperature 60°C, liquid–solid ratio 20:1 mL/g and extraction time 13 min. Moreover, an HPLC method using pentafluorophenyl column was established and validated. Good linearity was observed with the regression coefficients (r²) more than 0.999. The limit of detection (LODs) (S/N = 3) and limit of quantification (LOQs) (S/N = 10) for the components were less than 0.41 and 1.47 μg/mL, respectively. The inter‐ and intraday precisions that were used to evaluate the reproducibility and relative standard deviation (RSD) values were less than 4.57%. The recoveries were between 97.26 and 102.69%. The method was successfully used for the analysis of samples of pigeon pea leaves. In conclusion, the developed ILMAE‐HPLC‐diode array detector using pentafluorophenyl column method can be applied for quality control of pigeon pea leaves and related medicinal products.     

Ionic‐liquid‐based ultrasound/microwave‐assisted extraction of 2,4‐dihydroxy‐7‐methoxy‐1,4‐benzoxazin‐3‐one and 6‐methoxy‐benzoxazolin‐2‐one from maize (Zea mays L.) seedlings

We evaluated an ionic‐liquid‐based ultrasound/microwave‐assisted extraction method for the extraction of 2,4‐dihydroxy‐7‐methoxy‐1,4‐benzoxazin‐3‐one and 6‐methoxy‐benzoxazolin‐2‐one from etiolated maize seedlings. We performed single‐factor and central composite rotatable design experiments to optimize the most important parameters influencing this technique. The best results were obtained using 1.00 M 1‐octyl‐3‐methylimidazolium bromide as the extraction solvent, a 50°C extraction temperature, a 20:1 liquid/solid ratio (mL/g), a 21 min treatment time, 590 W microwave power, and 50 W fixed ultrasonic power. We performed a comparison between ionic‐liquid‐based ultrasound/microwave‐assisted extraction and conventional homogenized extraction. Extraction yields of 2,4‐dihydroxy‐7‐methoxy‐1,4‐benzoxazin‐3‐one and 6‐methoxy‐benzoxazolin‐2‐one by the ionic‐liquid‐based ultrasound/microwave‐assisted extraction method were 1.392 ± 0.051 and 0.205 ± 0.008 mg/g, respectively, which were correspondingly 1.46‐ and 1.32‐fold higher than those obtained by conventional homogenized extraction. All the results show that the ionic‐liquid‐based ultrasound/microwave‐assisted extraction method is therefore an efficient and credible method for the extraction of 2,4‐dihydroxy‐7‐methoxy‐1,4‐benzoxazin‐3‐one and 6‐methoxy‐benzoxazolin‐2‐one from maize seedlings.     

Determination of the oil content of seeds by focused microwave-assisted soxhlet extraction

Sumamry Soybean, rape and sunflower lipids have been extracted with a focused microwave-assisted Saxhlet extractor. The main factors affecting extraction efficiency, namely microwave irradiation power, number of cycles and microwave irradiation time were optimised by means of a power, number of cycles and microwave irradiation time were optimised by means of a central composite design based on a two-level-three-factor factorial design. A study of the influence of particle size on the extraction procedure was also performed. The results obtained were compared with those obtained by use of an ISO method using a conventional Soxhlet extractor. Quantitative results for lipid content based on gravimetric determinations and qualitative results based on analysis of fatty acid methyl esters and polymeric compounds were similar to those obtained by Soxhlet extraction with hexane. Substantial reduction of sample manipulation. analysis time and solvent wastage is achieved by use of the proposed 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.     

仿真饰品中邻苯二甲酸酯类增塑剂的含量测定和迁移风险考察

建立了仿真饰品中14种邻苯二甲酸酯类增塑剂的含量和迁移量测定的气相色谱-质谱(GC-MS)检测方法。考察了微波萃取、超声波萃取、快速溶剂萃取和索氏提取4种前处理方法对增塑剂含量测定的影响。在模拟人体温度及汗液环境下,考察了0～168 h内塑料仿真饰品中邻苯二甲酸二丁酯(DBP)、邻苯二甲酸二(2-乙基己基)酯(DEHP)和邻苯二甲酸二辛酯(DOP)3种增塑剂的迁移风险。结果表明微波萃取法的提取效率优于其余3种方法。所建立方法的定量限为5 mg/kg (邻苯二甲酸二异壬酯(DINP)、邻苯二甲酸二异癸酯(DIDP)为25 mg/kg),在0.1～50 mg/L(DINP、DIDP在0.5～250 mg/L)范围内,线性相关系数在0.99以上,在3个添加水平下的回收率在90.95%与98.67%之间。在模拟条件下,DEHP的迁移风险较高,浸泡72 h后约有0.75%溶出,而DBP和DOP的溶出风险较低。该法的灵敏度高、回收率高、选择性好,能满足实际工作的要求。     

Analysis of sediment-associated insecticides using ultrasound assisted microwave extraction and gas chromatography-mass spectrometry

An ultrasound assisted microwave extraction (UAME) method was developed to simultaneously extract five organophosphate (OP) and eight pyrethroid insecticides from sediment. The optimized UAME conditions were to use 100 ml of a mixture of hexane and acetone (1:1, v/v) solution as the extraction solvents, and extraction time, microwave and ultrasonic power settings of 6 min, 100 W and 50 W, respectively. Extracts were cleaned using solid phase extraction and analyzed by gas chromatography-mass spectrometry in negative chemical ionization mode and quantification was based on matrix-matched standard solutions along with internal standard calibration. At the spiked concentrations of 1, 5 and 20 ng/g dry weight (dw), recoveries of OPs were 77.6-122%, 65.2-128% and 75.6-141% with relative standard deviations (RSDs) of 10.6-18.1%, 3.1-12.5% and 8.0-35.3%, respectively, while recoveries of pyrethroids were 78.0-101%, 76.4-104% and 71.0-99.5% with RSDs of 10.3-23.5%, 4.7-17.6% and 8.8-18.7%, respectively. Method detection limits ranged from 0.31 to 0.45 ng/g dw for the OP insecticides and from 0.27 to 0.70 ng/g dw for the pyrethroid insecticides. The newly developed UAME method was validated by comparing it to Soxhlet and sonication extraction methods. Better recoveries were achieved for most OPs by the novel UAME method, whereas there was no significant difference in recoveries for most of the pyrethroids. Finally, the UAME method was used to quantify the target insecticides in field-contaminated sediment samples which were collected in Guangzhou, China.     

Development of an analytical method based on microwave-assisted extraction and solid phase extraction cleanup for the determination of organochlorine pesticides in animal feed

A method to determine 21 organochlorine pesticides in animal feed samples using microwave assisted extraction and solid phase extraction cleanup was optimised regarding its main parameters. After extraction with hexane-acetone (50:50), three different sorbents (alumina/ENVI-Florisil, ENVI-Carb and ENVI-Carb II/PSA) were assayed for the cleanup step. Analytes were eluted with hexane-ethyl acetate (80:20) and determined by gas chromatography and electron capture detection followed by gas chromatography-mass spectrometry. ENVI-Carb and ENVI-Carb II/PSA provided colourless eluates but fewer interferent compounds were found in ENVI-Carb II/PSA chromatograms, so this system was selected to carry out the purification of the extracts. The analytical recoveries obtained with this method were close to 100% in most cases with relative standard deviations lower than 10%. These percentages were similar to those obtained with the Soxhlet extraction procedure, which shows the method suitable for the determination of organochlorine pesticides in animal feed material. The method was also validated with the analysis of a certified reference material (CRM-115 BCR), and the results obtained were in good accordance with the certified values.     

Microwave assisted extraction of polycyclic aromatic hydrocarbons from atmospheric particulate samples

For several years, microwave assisted extraction (MAE) was applied to extract organic compounds such as polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls, etc., from soils, sediments and standard reference materials. Very few authors applied this methodology for the extraction of PAHs from atmospheric particulate matter. In the present study, MAE of polycyclic aromatic hydrocarbons with hexane/acetone (1:1) from real atmospheric particulate samples was investigated and the effect of microwave energy and irradiation time studied. The yields of extracted compounds obtained by microwave irradiation were compared with those obtained using traditional Soxhlet extraction. MAE was evaluated using spiked real atmospheric particulate samples and two standard reference materials. Analytical determinations of PAHs were carried out by high performance liquid chromatography (HPLC) with ultraviolet and fluorescence detection. The best recoveries were achieved with a microwave energy of 400 W and an irradiation time of 20 min.     

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。