气相色谱质谱法快速测定人血浆中克仑特罗

血浆样品经0.01mol·L-1盐酸和无水乙醇浸取,在碱性条件下用氯仿萃取,GG-MS-选择离子测量法测定,外标法定量。在选定的色谱条件下,盐酸克仑特罗的检出限为0.05ng,线性范围为0.1-100ng,方法的平均回收率为95.6％,RSD小于6.82％(n=6)。该法毋需衍生化,基质无干扰,简便可靠,适用于生物材料中克仑特罗的快速分析。     

Optical Properties of Model Compounds of Polyaniline

The UV and visible spectra of six model compounds were studied. These compounds can be considered as models of polyaniline in the reduced, cation radical, partially oxidized and oxidized forms. After treatment of a mixture of equal molar quantities of the reduced form (DPPD) and the oxidized form (QDIM) with acid, the following reaction was observed: DPPD(I)+QDIM(III)+2H⁺=2DPPD⁺(II) After similar treatment of the partially oxidized form (V) with acid, the radical cation salt formed. The UV and visible spectra of polyaniline in the reduced form, oxidized form and conductive form are similar to the spectra of DPPD, QDIM and DPPD⁺ or radical cation salt of V respectively. We propose that the polyaniline synthesized by chemical oxidation of aniline consists of oxidized and reduced repeat units. Upon protonation a redox reaction (or electron rearrangement) occurs and forms delocalized radical cations (polarons) in the polymer chain which are highly conductive.     

Isothermal Titration Microcalorimetric Studies of the Effect of Temperature on Hydrophobic Interaction between Proteins and Hydrophobic Adsorbents

This study attempted to comprehend how temperature affects hydrophobic interaction between proteins and hydrophobic adsorbents. By equilibrium batch analysis, we measured the adsorption isotherm to evaluate the protein-adsorbent affinity, while isothermal titration calorimetry was used to measure the adsorption enthalpy. In addition, the affinity and enthalpy differences between two proteins, alpha-chymotrypsinogen A and trypsinogen, with two adsorbents, butyl-Sepharose and octyl-Sepharose gel, under varying temperatures were studied with respect to the exposed hydrophobic segments of the protein and ligand hydrophobicity. The enthalpies obtained in this investigation can be used to more thoroughly understand the hydrophobic interaction between proteins and adsorbents. First, the adsorption isotherm experiments reveal that the adsorption quantity of the proteins with the Sepharose gels increases with temperature. For a microcalorimetric measurement, as temperature is increased from 298 to 310 K, the DeltaH value of alpha-chymotrypsinogen A with butyl-Sepharose increases, while the DeltaH value of trypsinogen is reduced. This is likely due to the fact that alpha-chymotrypsinogen A has a higher area of exposed hydrophobic segments than trypsinogen does. This observation also implies that as temperature increases, the interaction mechanism of alpha-chymotrypsinogen A with butyl-Sepharose changes from an adsorption-dominated process to a partitioning process. In addition, for octyl-Sepharose, the DeltaH value of alpha-chymotrypsinogen A is positive and decreases with temperature increment. However, the DeltaH value of trypsinogen was positive and increased with temperature. Therefore, we conclude that as temperature increases, the interaction mechanism of the proteins for octyl-Sepharose is a partitioning-dominated process. Copyright 2000 Academic Press.     

Taxumairols X--Z,new taxoids from Taiwanese Taxus mairei

In addition to 19-dydroxybaccatin III, 1beta-hydroxy-5 alpha-deacetylbaccatin I, taxayuntin G and 13-O-deacetyltaxumairol Z (4), three new taxane diterpenoids, taxumairols X (1), Y (2), Z (3) have been isolated from extracts of the Formosan Taxus mairei (LEMEE & LEVL.) S. Y. HU. Compounds 1-2 belong to the 11(15-->1)-abeo-taxane system, having a tetrahydrofuran ring at C-2, C-3, C-4 and C-20. The new compound 3 and 4, which was misidentified previously are derivatives of 11(15-->1)-abeo-taxane with an intact oxirane system. The structures of compounds 1-4 were elucidated on the basis of extensive two dimensional (2D)-NMR analysis.     

Atomic absorption inhibition titration of orthophosphate and polyphosphates

The atomic absorption inhibition titration of phosphates was studied for two types of burner. Dependence on gas Flow-rates was observed. The method with a pre-mix burner was employed to determine phosphate in surface and waste waters. The results are compared with those by the standard method. The proposed method was found to be rapid, simple and accurate.     

Selective separations by reactive ion exchange : Part III. Preconcentration and separation of oxo anions

A new procedure for simultaneous preconcentration, separation, and determination of permanganate, chromate and vanadate was developed for aqueous solutions containing p.p.b. levels of these anions (and molybdate). The presence of other (non-complexing) ions in p.p.m. concentrations did not interfere. The procedure consisted of reactive adsorption of all three anions as their reduced cations, on iron(II)-treated resin, followed by elution of vanadium(IV) with 0.01 M HNO₃/H₂O₂, manganese(II) with 0.35 M HCl, and chromium(III) with 4M HCl. Concentration factors of 40 were obtained with 1-l “samples” 10 p.p.b. concentrations were determined with standard deviations of 4–5 % by a.a.s. and conventional spectrophotometry.     

Low-temperature bath/coupled-capillary/sweeping-micellar electrokinetic capillary chromatography for the separation of naphthalene-2,3-dicarboxaldehyde-derivatized dopamine and norepinephrine

The use of a low-temperature (0 degrees C) bath-assisted coupled capillary for the separation of naphthalene-2,3-dicarboxaldehyde (NDA)-derivatized dopamine and norepinephrine using the sweeping-micellar electrokinetic capillary chromatography (MEKC) mode is described. In this technique, a capillary consisting of two portions with different inside diameters is used. Therefore, the field strength inside the capillary is different. Hence, the electrophoretic migration velocities of the analytes and the electro-osmotic flow (EOF) also are different. Furthermore, when a portion of the capillary (wide portion, used for sweeping) is immersed in a low-temperature bath, the viscosity of the buffer and the retention factor of the analytes inside are increased. Thus, not only are the interactions between the SDS micelles and the analytes increased, but the SDS-analytes also move more slowly. As a result, a more complete separation can be achieved, even when the sample injection volume is large, up to approximately 2 microL. In general, when the volume of an injected sample is larger, the effects of sweeping and separation would become insufficient, especially when the retention values (k) of the analytes are quite different. However, this limitation can be improved when the low-temperature bath/coupled capillary/sweeping-MEKC mode is used.     

Design and Synthesis of 1-Benzyl-3-(a-hydroxy-(un)substituted benzylidene)pyrrolidine-2,4-diones as Potential Herbicides

The inhibitors of 4-hydroxyphenylpyruvate dioxygenase (HPPD, EC 1.13.11.27) are an new kind of herbicides.[1]Generally, in structure, potent herbicides of this kind must possess: (1) a tricarbonyl methane structure and one of the three carbonyl groups must be a subustituted benzoyl group; (2) the compound must be able to enolise so that the enolate is capable of inhibiting HPPD enzyme by competitive combination with Fe2+, the reaction center of HPPD enzyme.[2]Recently, we noticed that the 3-acyltetramic acids form an expanding group of antibiotics and pigments from micro-organisms,[3] they display a range of biological activities[4] and all of this kind compounds possess all of the characters mentioned above. Tests of their antimicrobial activities indicated that the structure of the acyl substituent at the 3-position was important to many typical antibiotics.[4～6] These characters stimulated us to study this kind of compounds so as to discover new herbicides. In this report, we synthesized a series of compounds 3 and tested their herbicidal activities to investigate their structure-activity relationships.     

STUDY ON THE SYNTHESIS AND PROPERTIES OF MACRORETICULAR IPN POLYACRYLAMIDE—POLY(VINYL—ETHYLENEDIAMINE)CHELATE SORBENTS

A new series of MR-IPN polyacrylamide—poly(vinyl-ethylenediamine)chelatesorbents were prepared by the reaction of ethylenediamine with MR-IPN matrixes.The newchelate sorbent showed good sorption properties for auric and platinic ions.     

Adsorption of NH3 onto activated carbon prepared from palm shells impregnated with H2SO4

Adsorption of ammonia (NH3) onto activated carbons prepared from palm shells impregnated with sulfuric acid (H2SO4) was investigated. The effects of activation temperature and acid concentration on pore surface area development were studied. The relatively large micropore surface areas of the palm-shell activated carbons prepared by H2SO4 activation suggest their potential applications in gas adsorption. Adsorption experiments at a fixed temperature showed that the amounts of NH3 adsorbed onto the chemically activated carbons, unlike those prepared by CO2 thermal activation, were not solely dependent on the specific pore surface areas of the adsorbents. Further adsorption tests for a wide range of temperatures suggested combined physisorption and chemisorption of NH3. Desorption tests at the same temperature as adsorption and at an elevated temperature were carried out to confirm the occurrence of chemisorption due to the interaction between NH3 and some oxygen functional groups via hydrogen bonding. The surface functional groups on the adsorbent surface were detected by Fourier transform infrared spectroscopy. The amounts of NH3 adsorbed by chemisorption were correlated with the contents of elemental oxygen present in the adsorbents. Mechanisms for chemical activation and adsorption processes are proposed based on the observed phenomena.