高效液相色谱法测定山楂中的苦杏仁甙

 建立了从山楂中提取苦杏仁甙的方法,样品先用石油醚脱脂，然后用甲醇进行索氏提取。用高效液相色谱法定量测定了山楂中的苦杏仁甙,色谱条件如下：反相C18柱,流动相为15%的甲醇水溶液,检测波长为215 nm。测定了含不同比例山楂籽的山楂样品,结果表明含山楂籽比例高的山楂样品中苦杏仁甙的含量高,且山楂粗粒样品中苦杏仁甙的提取量比粉末样品的提取量高。     

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.     

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。     

Chaotic Time-Delay Signature Suppression and Entropy Growth Enhancement Using Frequency-Band Extractor

By frequency-band extracting, we experimentally and theoretically investigate time-delay signature (TDS) suppression and entropy growth enhancement of a chaotic optical-feedback semiconductor laser under different injection currents and feedback strengths. The TDS and entropy growth are quantified by the peak value of autocorrelation function and the difference of permutation entropy at the feedback delay time. At the optimal extracting bandwidth, the measured TDS is suppressed up to 96% compared to the original chaos, and the entropy growth is higher than the noise-dominated threshold, indicating that the dynamical process is noisy. The effects of extracting bandwidth and radio frequencies on the TDS and entropy growth are also clarified experimentally and theoretically. The experimental results are in good agreements with the theoretical results. The skewness of the laser intensity distribution is effectively improved to 0.001 with the optimal extracting bandwidth. This technique provides a promising tool to extract randomness and prepare desired entropy sources for chaotic secure communication and random number generation.     

内导体对相对论返波振荡器工作波段选择的影响

 设计了一种紧凑型、GW级同轴引出电子束相对论返波振荡器,利用KARAT 2.5维全电磁粒子模拟程序研究了器件内部束 波作用的物理过程。模拟结果表明：当器件中使用内导体,在电子束能量700 keV,电子束流11 kA,导引磁场为1.0 T时,能实现L波段2.66 GW高功率微波输出,平均效率约为34%;去掉内导体时,能实现S波段1.88 GW单频微波输出,平均效率约为24%。同一个器件,仅通过装卸内导体就可以选择在两个波段实现GW级、高效微波输出,这对于高功率微波器件的设计有一定的参考意义。     

Enhanced Preconcentration of Pesticides from Water Using the Goulden Large-Sample Extractor

Abstract

Recoveries of nine model pesticides measured in water samples ranging from 4 to 120 liters using the Goulden large-sample extractor and were similar to recoveries predicted by a continuous liquid-liquid extraction model. Recoveries from the largest volumes were affected by emulsion formation at high sample flow rates. Limits of detection using the Goulden extractor under optimized conditions were lower than those obtained from 1 liter serial batch extractions by factors inversely proportional to sample volumes for pesticides with logarithm of solvent/water partition coefficients greater than 2. Average limits of detection for the pesticides were 9ng/l for 10 liter samples and 1 ng/l for 120 liter samples. Extraction of large water samples with methylene chloride using the Goulden large-sample extractor is an alternative technique to extraction of water by using solid-phase sorbents.     

加速溶剂萃取法与索氏提取法对废线路板中二噁英测定的影响

将经过多级破碎分选所得的废线路板粉末过60目筛,以2 mol/L HCl溶液、超纯水洗涤,并用丙酮脱水.将预处理后的滤渣、滤纸填入萃取池,或者用新滤纸包裹后置于索氏提取管内,添加5 μL内标物,分别用加速溶剂萃取法(ASE)或索氏提取(SE)法进行萃取,依次采用多层硅胶柱和活性炭柱对萃取提取物进行净化、洗脱,得到二噁英测试样品.用同位素稀释-高分辨气相色谱-质谱联用仪分析样品中二噁英的含量.考察两种提取方法及不同氯代数对15种13C-2,3,7,8-PCDD/Fs回收率的影响,比较两种方法的准确度和精密度.结果表明,ASE和SE对15种13C-2,3,7,8-PCDD/Fs的回收率分别为54.3%~113.0%和28.3%~77.7%, 实测废线路板中二噁英毒性当量(Toxic equivalent quangtity,TEQ)分别为0.075 ng TEQ/kg和0.266 ng TEQ/kg.在方法精密度允许范围内,ASE相对具有简单快速、溶剂用量少和准确的优势.     

Extraction of polycyclic aromatic nitrogen heterocycles from spiked soil samples

Extraction recovery of 10 selected polycyclic aromatic nitrogen heterocycles (PANHs), quinoline, 2-methylquinoline, 6-methylquinoline, 8-methylquinoline, acridine, benzo[h]quinoline, phenantridine, indole, 2-methylindole, and carbazole from spiked soil samples was tested. Four different extraction techniques, pressurized solvent extraction (PSE), supercritical fluid extraction (SFE), Soxhlet warm extraction (SOXW) and standard Soxhlet extraction (SOX), were applied and compared. The RP-HPLC technique with a silica-based octadecyl stationary phase was used for recovery determination of individual PANHs. Supercritical fluid extraction has been found to be the most effective method for the extraction of selected PANHs from soil. PSE and SOXW methods offered similar results with slightly lower extraction recoveries compared with SFE. On the contrary, SOX is a time-consuming method with a low recovery of target analytes and is not suitable for the extraction of PANHs from soils.     

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.     

Photoluminescence from xylene modified anatase TiO2 nanocrystals

The surface of anatase TiO₂ nanoparticles was modified by xylene using soxhlet extractor. The photoluminescence (PL) of the modified nanoparticles was investigated. A stable and strong blue luminescence peak at 420 nm can be observed, and the intensity of the PL peak increases with the increase of the extraction time.