对硫磷分子印迹聚合物在固相萃取中的应用

采用分子印迹技术,以对硫磷为模板分子,二乙烯三胺为固化剂,环氧树脂为单体,聚乙二醇为致孔剂,制备了具有良好识别性能的分子印迹聚合物.系统考察了对硫磷与其结构类似物在该聚合物上的选择性分离富集特性.用聚合物固相萃取了小白菜中的对硫磷.结果表明,聚合物对模板分子产生了印迹效应,对对硫磷有明显的选择性.本文采用C18色谱柱,...     

电色谱模式下四肽印迹整体柱分子识别机理的研究

本文采用原位聚合法制备了以四肽YPLG为模板的毛细管分子印迹整体柱,在毛细管电色谱模式下以模板分子和它的结构类似物YPGL为样品,对分子印迹聚合物的识别机理进行了研究。这两种四肽由于化学结构相似且等电点非常相近,普通的电色谱和毛细管电泳方法分离非常困难。但我们的实验表明,印迹整体柱对模板分子具有特异性识别能力,因此YPLG与YPGL之间的分离因子为1.73,分离度达3.72。实验中系统地研究了流动相中有机溶剂的含量、缓冲溶液的pH值、缓冲溶液的盐浓度以及柱温对四肽识别的影响。实验中我们观察到模板在印迹柱上具有非线性的Van’t Hoff行为,揭示可能存在多重保留机理。本研究结果表明,在毛细管电色谱模式下,分子印迹整体柱的分子识别主要决定于样品与印迹聚合物之间的氢键作用以及印迹孔穴的三维结构。     

分子印迹整体柱快速分离烟酰胺及烟酸

以药物烟酰胺为模板分子,甲基丙烯酸为功能单体,乙二醇二甲基丙烯酸酯为交联剂,甲苯和正十二醇的混合溶液为致孔剂,采用原位聚合法制备了具有特定识别性能和分离能力的分子印迹聚合物,并将其作为高效液相色谱固定相,实现了模板分子与烟酸在2 min内的快速分离。在规格为50 mm×4.6 mm i.d.色谱柱上,以纯水为流动相（流速为7.0 mL/min）、操作温度为室温的色谱条件下,模板分子与烟酸的分离度达1.8。讨论了流动相中有机溶剂含量、醋酸及碱含量和流速对分离的影响。结果表明,原位聚合法制备的整体分子印迹聚合物在以纯水作流动相时对模板分子与其类似物有快速分离能力,这对于体内药物的分离富集研究具有很好的应用前景。     

反相气相色谱研究金属离子中介甲醛印迹聚合物的气相识别

采用配位聚合法制备了Co2+中介的甲醛印迹聚合物,用红外光谱和扫描电镜研究了分子印迹聚合物的表面结构。以甲醛印迹聚合物作为气相色谱固定相,采用反相气相色谱技术研究了印迹材料对模板及其结构相似物的选择保留性能、等温吸附及吸附热力学,并探讨了分子印迹聚合物对室内空气中甲醛的脱除效果。结果表明,在相同色谱条件下,分子印迹柱对模板分子的容量因子均远高于乙醛。较低柱温和较低载气流速有利于印迹材料对气态模板分子的选择保留,当柱温为90℃,载气流速7.0 mL/min,进样体积为3.0μL时,分子印迹柱对模板的容量因子高达61.1,对模板及结构类似物的分离因子达到10.66。模板分子在印迹聚合物柱上的气相吸附等温线呈近似线性,而结构类似物乙醛的吸附等温线符合BET吸附的Ⅲ类模型。分子印迹聚合物对室内空气中的甲醛也具有一定的脱除能力。     

腈菌唑分子印迹聚合物的制备及识别性能研究

以腈菌唑为模板分子，采用原位分子印迹技术，制备具有特定识别性能的连续棒状分子印迹聚合物。考察了流动相中酸量对分离的影响，研究了几种结构类似物在所得分子印迹柱上的保留特性。结果表明，这种棒状分子印迹聚合物比相应的空白聚合物有高的识别性能和选择性。     

L-组氨酸手性识别印迹固定相的制备及表征

以L-组氨酸为模板分子, 甲基丙烯酸为功能单体, 乙二醇二甲基丙烯酸酯为交联剂, 偶氮二异丁腈为引发剂, 在水-乙腈微乳体系中采用沉淀聚合方法制备了具有手性识别L-组氨酸功能的印迹微球. 采用静态平衡吸附实验及色谱分析探讨聚合微球对模板分子的选择识别吸附性能. 结果表明, 该印迹聚合物微球对模板分子存在两种结合位点, 最大表观结合量分别为33.04和24.16 μmol/g. 相对于常规的C18柱, 该印迹聚合物填充柱能够完全分离L-组氨酸和D-组氨酸, 分离度R为2.23, 选择因子为2.14. 利用差热分析、红外光谱及X射线衍射等技术表征聚合物微球的热性能及结构. 结果表明, 聚合物微球具有良好的热稳定性, 是一种具有部分晶体结构的聚合物.     

邻苯二甲酸-乙酸铜分子印迹聚合物识别性能的研究

以邻苯二甲酸与乙酸铜的配合物为模板, 在甲醇溶剂中制备印迹聚合物, 对其色谱保留行为及结构类似物的识别性能进行了研究. 结果表明, 在甲醇溶液中, 该印迹聚合物不仅能够区分模板分子的结构类似物, 而且对配合物的金属阴、阳离子都具有很好的识别作用. 以邻苯二甲酸为模板制备的聚合物对模板分子本身的保留较弱, 但对模板与铜的配合物却表现出了很强的保留值, 在此从结构分析的角度给出了解释.     

2,4-二氯苯氧乙酸分子印迹整体柱的制备、表征及色谱性能研究

以2,4-二氯苯氧乙酸分子为模板,甲基丙烯酸为单体,乙二醇二甲基丙烯酸酯为交联剂,甲苯和十二醇为混合致孔剂,采用热引发原位聚合法制备了作为高效液相色谱固定相的分子印迹整体柱.用红外光谱、扫描电镜、比表面积分析法对聚合物进行了表征.考察了模板分子在不同条件下合成的印迹整体柱及空白整体柱上容量因子的变化规律,同时探讨了流动相中甲醇的体积分数、pH值、流速对印迹整体柱分离性能的影响.结果表明,在优化的合成条件下制备的分子印迹整体柱可在15 min内分离2,4-二氯苯氧乙酸及其类似物苯氧乙酸,分离度为1.52.对柑桔提取液进行了分离测试,结果满意.     

类模板分子印迹整体柱测定甲氧苄啶的研究

利用三聚氰胺(MAM)与甲氧苄啶(TMP)分子中嘧啶环局部结构类似的特性,以三聚氰胺为类模板分子,甲基丙烯酸(MAA)为功能单体,二甲基丙烯酸乙二醇酯(EDMA)为交联剂,原位聚合法制备了对甲氧苄啶(TMP)有识别作用的分子印迹(MIP)整体柱.在优化的色谱条件下,该印迹整体柱对甲氧苄啶显示出选择性识别作用,而对叶酸、...     

樟脑分子印迹整体柱的制备及性能评价

利用原位聚合法制备了樟脑分子印迹整体柱作为液相色谱固定相,通过优化制备条件和色谱条件,得到了对模板分子有较高保留性能的整体柱。采用前沿色谱分析法测定柱容量,得到有效结合位点Bt=1.815×102mmol/g和解离常数Kd=9.064 mmol/mL。Van’t Hoff方程得到的热力学参数焓值和熵值,说明了聚合物对樟脑的吸附为熵增过程。等温吸附模型证明在该聚合物表面只存在一种结合位点。     

Photochemical ring opening of barbital

Photolysis of barbital yields derivatives of urea and biuret. The mechanism of ring opening involves an isocyanate intermediate.     

多亚甲基桥连双巴比妥的合成及鉴定

在ＰＴＣ条件下合成了多亚甲基桥连的双巴比妥类化合物１～３，并通过了元素分析，ＩＲ及＾１ＨＮＭＲ予以鉴定。     

Sur le Polymorphisme du barbital et le systeme eau-barbital

The crystal structures of three forms (I, II and IV) of barbital are well known.The DTA curve of barbital I is marked by only one endotherm, at 186°, which is the melting point of this crystalline form. For barbital II, the DTA curve shows a first endotherm at 160°, which indicates the transition point II I, and then an endotherm at 186° for the melting of form I. By fast cooling of a boiling saturated aqueous solution, another crystalline form of barbital (form X) can be obtained. The DTA curve of this new sample shows another endotherm, at 119°, preceding the endotherms at 160 and 186°. Though the TG curve does not indicate any weight loss at this temperature, this endotherm does not indicate a new phase transition, but a monotectic equilibrium.This monotectic equilibrium (x _L1=78 mol % H₂O,x _L2=98 mol % H₂O) is observed at 119° in the phase diagrams (isochöric sections atV/m=7 cm³·g^–1) of the water-barbital systems established for form I, form II and form X.

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Zusammenfassung Die Kristallstrukturen von 3 Barbitalformen (I, II und IV) sind gut bekannt. Die DTA-Kurve von Barbital I weist nur einen endothermen Peak bei 186° auf, der dem Schmelzpunkt dieser kristallinen Form entspricht. Die DTA-Kurve von Barbital II zeigt einen ersten endothermen, dem Umwandlungspunkt II I kennzeichnenden Peak bei 160° und dann einen zweiten endothermen Peak bei 186° für das Schmelzen der Form I. Durch schnelles Abkühlen einer kochenden gesättigten wässrigen Lösung kann eine andere kristalline Form des Barbitais (Form X) erhalten werden. Die DTA-Kurve dieser neuen Probe zeigt einen weiteren endothermen Peak bei 119°. Obwohl aus der TG-Kurve bei dieser Temperatur kein Gewichtsverlust ersichtlich ist, zeigt dieser endotherme Peak doch keinen neuen Phasenübergang, sondern ein monotektisches Gleichgewicht an. Dieses monotektische Gleichgewicht (x _L1=78 mol% H₂O,x _L2=98 mol% H₂O) wird in den Phasendiagrammen (isochore Schnittpunkte beiV/m=7 cm³·g^–1) der für die Formen I, II and X aufgestellten Wasser/Barbital-Systeme bei 119° beobachtet.

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: I, II IV. I 186°, . II 160°, II I, 186°, I. ( X), . 119°, 160 186°. - , , . (x _Li=78 % ,x _Li=98 % ) 119° ( V/m=7 cm³ · ^–1) - , I, II X.

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A la suite de ce travail, nous envisageons également de rechercher les phases qui seraient susceptibles d'abaisser la température de l'équilibre monotectique.     

X-ray structural studies on two forms of β-cyclodextrin barbital complexes

The crystal structures of two forms of -cyclodextrin barbital complexes (Form I and Form II) were investigated by X-ray analysis. In Form I crystal, two -cyclodextrin(-CyD) molecules including two barbital molecules form a dimeric structure by the hydrogen bonds among their secondary hydroxyl groups. The unit cell volume of Form II is about twice as large as that of Form I and there exist two -CyD dimers in Form II. Although the (Host)/(Guest) ratio is 1/1, only one barbital molecule can be found in Form II at the present stage. The sinilarities and differences between the two crystal structures are mainly discussed here.     

Molecular recognition of biotin, barbital and tolbutamide with new synthetic receptors

We have measured, by means of NMR titrations, the binding constants for the complexes between hosts N,N′-bis(6-methylpyridin-2-yl)-1,3-benzenedicarboxamide (7) and 4-chloro-N,N′-bis(6-methylpyridin-2-yl)-2,6-pyridinedicarboxamide (8, hydrated) with biotin methyl ester (1), N,N′-dimethylurea (2), 2-imidazolidone (3), N,N′-trimethylenurea (4), barbital (5) and tolbutamide (6) as guests. Molecular Mechanics calculations (Monte Carlo Conformational Search, AMBER and OPLS force fields, MacroModel v.8.1) on the complexes formed between the foregoing guests and hosts 7 and 8, comparatively with 4-oxo-N,N′-bis(6-methylpyridin-2-yl)-1,4-dihydro-2,6-pyridinedicarboxamide (9a) have been carried out in order to determine the correlation between experimental and theoretical results and to understand the behaviour of the designed new hosts. Finally we have performed single point DFT [B3LYP/6-31G(d,p)] calculations on the optimised Molecular Mechanics geometries for the complexes between hosts 7-9 and water.     

Structural studies of cyclic ureas: 3. Enthalpy of formation of barbital

A thermochemical and thermophysical study has been carried out for crystalline barbital [5,5′-diethylbarbituric acid]. The thermochemical study was made by static bomb combustion calorimetry, from which the standard () molar enthalpy of formation of the crystalline barbital, at T = 298.15 K, was derived as −(753.0 ± 1.8) kJ · mol⁻¹. The thermophysical study was made by differential scanning calorimetry over the temperature interval (265 to 470) K. A solid–solid phase transition was found at T = 413.3 K. The vapour pressures of the crystalline barbital were measured at several temperatures between T = (355 and 377) K, by the Knudsen mass-loss effusion technique, from which the standard molar enthalpy of sublimation, at T = 298.15 K was derived as (117.3 ± 0.6) kJ · mol⁻¹. The combination of the experimental results yielded the standard molar enthalpy of formation of barbital in the gaseous phase, at T = 298.15 K, as −(635.8 ± 1.9) kJ · mol⁻¹. This value is compared and discussed with our theoretical calculations by several methods (Gaussian-n theories G2 and G3, complete basis set CBS-QB3, density functional B3P86 and B3LYP) by means of atomization and isodesmic reaction schemes.     

液相微萃取-气相色谱法测定尿液中氨基比林、安替比林和巴比妥的研究

建立了一种以液相微萃取(Liquid Phase Microextraction,LPME)与气相色谱-氢火焰(LPME-GC-FID)联用技术为基础的测定尿样中氨基比林、安替比林和巴比妥的方法。考察了萃取溶剂、萃取时间、pH对萃取效果的影响。氨基比林、安替比林、巴比妥线性范围分别为1.67~333、133~667、60~300 mg/L,检出限分别为1、4、12 mg/L。     

Overview of capillary electrophoresis and capillary electrochromatography.

This paper provides an overview on the current status of capillary electrophoresis (CE) and capillary electrochromatography (CEC). The focus is largely on the current application areas of CE where routine methods are now in place. These application areas include the analysis of DNA, clinical and forensic samples, carbohydrates, inorganic anions and metal ions, pharmaceuticals, enantiomeric species and proteins and peptides. More specific areas such the determination of physical properties, microchip CE and instrumentation developments are also covered. The application, advantages and limitations of CEC are covered. Recent review articles and textbooks are frequently cited to provide readers with a source of information regarding pioneering work and theoretical treatments.