非水液相微萃取-高效液相色谱法测定大黄中5种游离蒽醌类化合物

目的利用非水液相微萃取-高效液相色谱法(HPLC)同时测定大黄中游离蒽醌类化合物的含量。方法利用自制的液相微萃取装置,以聚偏氟乙烯中空纤维为溶剂载体,正己醇为萃取溶剂,供相为甲醇,接受相为1mmol/LNaOH,搅拌速度为1500r/min,萃取时间为50min。萃取结束,接受相在434nm处进行HPLC分析。结果在优化的液相微萃取条件下,芦荟大黄素、大黄酸、大黄素、大黄酚和大黄素甲醚的线性范围、回收率、精密度和检测限分别为:0.015～13.2、0.075～11.2、0.085～12.8、0.096～14.4、0.117～17.6μg/ml;103.8%～106.1%;2.5%～5.2%和2.9～20.0ng/ml。结论本法选择性高,有机溶剂消耗少,能快速、准确地测定大黄药材中游离蒽醌类化合物。

非水液相混合有机污染物的过冷液体溶解度间接测量

存在于混合物中的有机污染物是现代生活环境中常见的危害性较高的污染物。有机物过冷液体溶解度不仅是环境科学研究领域的重要概念,也是环境监测、环境质量评价、制定污染治理方案所需要的重要参数。由于过冷液体溶解度无法通过常规的实验方法进行测量,只能借助热力学计算取得。但是已有的热力学参数欠缺、精度不够,很多有机物的过冷液体溶解度或者无法准确计算,或者差异巨大。针对非水液相混合有机污染物中过冷液体溶解度取值问题,本文提出了一种测量过冷液体溶解度的实验方法,即采用批处理实验在不同摩尔分数点取得该点的平衡浓度,根据实验结果将不同摩尔分数点的平衡浓度外推(依线性或者非线性规律)至摩尔分数为一时,得到值为过冷液体溶解度。本文对对几种多环芳香烃进行了实验研究,并将实验结果的与其它方法得到的数值进行比较。结果与已经发表数值吻合,证实该方法的准确性和可靠性。同时也点评了该方法的局限性及应用前景。

液/液两相催化新进展——温控非水液/液两相催化

温控非水液 /液两相催化 ,是指一类由两种或多种液态有机物组成的催化反应体系 ,其特点是体系的相态变化可通过温度来调控 ,即体系在高温时相互混溶呈均相 ,低温不溶分成两相 ,催化剂和产物分别处于两相 ,从而为解决均相催化剂分离难的问题开拓了一个新方向 ,是液 /液两相催化研究领域最引人注目的进展之一 .首次以“温控”为主线将氟两相催化作为温控液 /液两相催化的一个特定类型纳入“温控非水液 /液两相催化”范畴 ,并与其它通过温度来调控的有机液

液相微萃取-高效液相色谱法测定银杏叶中槲皮素山柰素和异鼠李素的含量

目的:利用基于中空纤维为支持体的非水液相微萃取/后萃取-高效液相色谱法同时测定中药银杏叶中槲皮素、山柰素和异鼠李素的含量。方法:对影响萃取富集效率的实验条件进行优化,选定了聚砜纤维长度为10cm,正辛醇为萃取溶剂,含HCl 1×10-3 mol/L的甲醇溶液2.00mL为供相,pH10的NaOH为接受相,以1 500r/min搅拌萃取30min。萃取完成后,取接受相20μL进样高效液相色谱分析。结果:槲皮素、山柰素与异鼠李素的线性范围分别为:0.37～49.87,0.37～49.87和0.19～25.69μg/mL,相关系数均大于0.994。检测限分别为40、70、90ng/mL。平均回收率分别为89.9%～103.4%,101.3%～115.0%,97.3%～107.3%(n=5)。RSD分别为4.6%、3.7%和4.3%。结论:该方法能有效去除复杂基体的干扰,适用于银杏叶中槲皮素、山柰素和异鼠李素的含量测定。

Kinetic Mass Transfer Between Non-aqueous Phase Liquid and Gas During Soil Vapor Extraction

The mass transfer between non-aqueous phase liquid(NAPL) phase and soil gas phase in soil vapor extraction(SVE) process has been investigated by one-dimensional venting experiments. During quasi-steady volatilization of three single-component NAPLs in a sandy soil, constant initial lumped mass transfer coefficient (λgN,0) canbe obtained if the relative saturation (ξ) between NAPL phase and gas phase is higher than a critical value (ξc), andthe lumped mass transfer coefficient decreases with ξ when ξ＜ξc. It is also shown that the lumped mass transfercoefficient can be increased by blending porous micro-particles into the sandy soil because of the increasing of theinterfacial area.

Testing of NAPL simulator to predict migration of a light nonaqueous phase liquid(LNAPL) under water table fluctuation in a sandy medium

Nanoqueous phase liquid(NAPL) simulator is a powerful and popular mathematical model for modeling the flow and transport of non-aqueous phase liquids in subsurface,but the testing of its feasibility under water table fluctuation has received insufficient attention.The feature in a column test was tested through two cycles of water table fluctuation.The sandy medium in the column was initially saturated,and each cycle of water table fluctuation consisted of one water table falling and one rising,resulting in a drainage and an imbibition of the medium,respectively.It was found that the difference between the simulated and measured results in the first drainage of the column test was minor.However,with the propagation of the water table fluctuations,the simulation errors increased,and the simulation accuracy was not acceptable except for the first drainage in the two fluctuation cycles.The main reason was proved to be the estimation method of residual saturation used in this simulator.Also,based on the column tests,it was assumed that the resulting residual saturation from an incomplete imbibition process was a constant,with a value equal to that of the residual value resulting from the main imbibition process.The results obtained after modifying NAPL simulator with this assumption were found to be more accurate in the first cycle of water table fluctuation,but this accuracy decreased rapidly in the second one.It is concluded that NAPL simulator is not adequate in the case of LNAPL migration under water table fluctuation in sandy medium,unless a feasible assumption to estimate residual saturation is put forward.

One-Stage Technology for Production of Concentrated Ethylene Glycol-Water Solutions （Automotive Antifreeze）

The reactor unit for one-stage technology for production of concentrated ethylene glycol-water solutions is described.Such solutions could be useful for production of automotive antifreezes. The technology is based on the highly selective hydration ofethylene oxide in the presence of heterogeneous catalyst-anion-exchange resin in HCO3-/CO/3/2-_form. The mathematical model of reactor allowed evaluating of economical benefit in comparison with conventional method.

温控液/液两相催化进展

本文以作者在温控水/有机两相及温控非水液/液两相催化领域的研究工作为主线,对这一领域的研究进展做一评述,重点是环绕经典水/有机两相催化体系存在"应用范围受底物水溶性限制"的根本问题展开。特别是对"温控相转移催化"做了较为详细的介绍,同时,按体系介质不同,对氟两相体系、PEG两相体系、离子液体两相体系等非水液/液两相体系以及温控相分离催化分别做了阐述。

Experimental study on applicability of using time-domain reflectometry to detect NAPLs contaminated sands

Underground contamination by non-aqueous phase liquids (NAPLs) becomes increasingly serious. Rapid and reliable detection of contaminated zone and degree is the first step to site remediation. In this paper, diesel and fine sand are used as experiment materials to investigate the applicability of using time-domain reflectometry (TDR) to detect LNAPLs contamination. The major work includes: measurement of dielectric constant and electrical conductivity for the diesel-water-air-sand mixtures; measurement of reflection waveform and dielectric constant for specimens with a diesel contaminated layer being sandwiched in sand. The experimental results show the followings: A significant decrease in both dielectric constant and electrical conductivity is observed for the diesel-water-air-sand mixtures when diesel displaces the pore water, and the content of diesel can be calculated by the model; insignificant change in dielectric properties is measured when diesel only displaces the pore gas; when the diesel contaminated sand is sandwiched between two saturated sand layers, the interfaces of the diesel contaminated layer can be identified by analyzing the reflection waveform; for field application, TDR method is valid for the case that LNAPLs seep into saturated sand layer, and the applicability of TDR method in vadose zone depends on the initial saturation of the sand layer. The findings obtained in this paper provide a guidance for the use of TDR for the field investigation of NAPLs contaminated site.