Séparation des terres rares par chromatographie sur échangeurs d'ions II. Séparation et analyse de la paire europium-gadolinium [1]

A displacement chromatography technique is described for the separation of europium and light rare earths using the eluent ethylene-diaminetetraacetate buffered by ammonium acetate giving a determined pH in the separation columns. This method gives concentrations up to 20 g of pure rare earth oxides per liter of eluate. A chromatographic method of analysis of europium in presence of other rare earths is also described.     

Preparation of 3,3-disubstituted oxindoles by addition of malonates to 3-halo-3-oxindoles

A method for the synthesis of 3,3-disubstituted oxindole derivatives is described. This involves the base-mediated addition of malonate esters to 3-halo-3-alkyloxindoles. The addition is tolerant of a range of alkyl substituents at position 3 of the oxindole. Addition to an aryl chloro-oxindole is also described.     

A new method for the determination of radon in soil air by the “open vial” and integral counting with a liquid scintillation counter

A new method is described for the determination of Rn in soil gas. Open vials containing a liquid scintillator solution, suspended in a hole of the ground surface, absorb a fixed proportion of Rn present in soil gas. This allows the total Rn concentration to be determined. The method described is rapid, simple and reproducible. It should have many kinds of field application.     

Sequencing of antisense DNA analogues by capillary gel electrophoresis with laser-induced fluorescence detection

A method using capillary gel electrophoresis with laser-induced fluorescence detection is described which permits complete sequence determination of antisense DNA analogues of unknown sequence. This method, originally created as a tool to confirm the sequence of antisense oligonucleotides being developed as therapeutic drugs, utilizes data collected under a range of experimental conditions described by the Ogston model as applied to gel electrophoresis. A linear relationship independent of experimental conditions between the relative electrophoretic migration time and the oligonucleotide base number was observed and is shown to be consistent with a simplified version of this model and can be used to facilitate the sequence determination.     

meso-去甲二氢愈创木酸和Machilin A的合成

报道了一条合成内消旋去甲二氢愈创木酸(meso-NDGA)和Machilin A的新路线. 此路线通过两次Stobbe缩合构建木脂素结构骨架, 经官能团转换, 合成了meso-NDGA和Machilin A. 该路线操作简便、实用性强.     

Gas Chromatographic Analysis of Aminothiol Radioprotective Compounds

Abstract

A gas chromatographic method is described for aminothiols and disulfides. This method is based upon the formation of the trimethysilyl derivatives and their separation by gas chromatography. The kinetics of the derivative formation were investigated. A synthetic method for C4 to C6 aminothiols is given.     

Application of a dynamic method of minimisation in the study of reaction surfaces

This paper describes the application of Snyman's dynamic minimisation method to a fitted potential surface of H₃. Comparisons are made with conventional algorithms. A method is described to extend Snyman's method so that it will find only a particular kind of stationary point. It is emphasized that this method enables saddle points to be found without having to resort to approaches based on trial and error.     

Determination of vancomycin related substances by gradient high-performance liquid chromatography

A gradient high-performance liquid chromatographic method for the determination of vancomycin related substances is described. This method was developed to profile vancomycin, co-fermentation products, and degradation products. The resultant chromatograms confirm the multifactored nature of vancomycin, separating a number of peaks from the main component. The development of acceptable chromatographic performance is described, with the final method intended for use as a control assay. Quantitation of total related substances is made by comparing the relative area of the main peak to total peak area in a pair of chromatograms from a stock solution and a twenty-five fold dilution. A rapid-scan UV detector was used to demonstrate the similar spectral characteristics of the vancomycin related substances, confirming the validity of the relative area approach. Statistical method validation data are included, evaluating the use of this method for quantitative applications. Example applications demonstrate the effectiveness of this method.     

HPLC method for the analysis of cyproterone acetate in tablets

A reversed-phase high-performance liquid chromatographic (HPLC) method is described for the analysis of cyproterone acetate in tablets. This steroid is extracted and quantitated using a C18 column. This procedure is shown to be rapid, simple, and valid in terms of recovery, linearity, and precision. Application of this method to analyze dilute samples obtained from dissolution testing is demonstrated.     

Purification and analysis of hematoporphyrin and hematoporphyrin derivative by gel exclusion and reverse-phase chromatography

A ternary-solvent HPLC method for analysis of the components of the tumor-localizing product HPD is described. This HPLC system was used to assess the utility of a new method, based on gel exclusion chromatography, for purification of hematoporphyrin.     

Isolation of an outer membrane protein complex from Borrelia burgdorferi by n-butanol extraction and high-performance ion-exchange chromatography

Borrelia burgdorferi, the causative agent of Lyme disease, expresses two major membrane proteins, designated outer surface proteins A and B, which are of antigenic relevance, especially in the chronic phase of Lyme disease. Both proteins exhibit strain-related molecular weight variation. A method is described for obtaining these proteins from the bacterial membrane, without the use of detergents, by a combination of n-butanol extraction and cation-exchange chromatography on a Mono S fast protein liquid chromatographic column. This method yields up to five times larger amounts of the proteins in aqueous solution than previously described protocols, which applied ionic or non-ionic detergents. A comparison of extracts obtained by this method from different Borrelia burgdorferi strains is reported.     

Simplex optimization of the adaptive kalman filter

A method for determining concentrations from overlapped spectral data when a complete model is not available is described. This approach combines simplex optimization with the adaptive Kalman filter to yield a method in which initial guesses for the adaptive filter are generated by the simplex algorithm. The performance of the method is demonstrated by deconvoluting overlapped synthetic data and spectral data.     

Determination of chloramphenicol in urine,feed water,milk and honey samples using molecular imprinted polymer clean-up

A method for determination of low concentrations of chloramphenicol in urine, feed water, milk and honey was developed. A comparison was carried out between a routinely used analytical method based on solid phase extraction (SPE-C18) for cleaning the extract and the new procedure for the sample preparation using columns based on the molecular imprinted polymers (MIP) principle. The extracts obtained from the MIP clean-up procedure were clean enough for chromatografic analyses. Confirmatory analyses were conducted using GC/MS-NCI after derivatisation (silylation). The described method was fully validated according to CD 2002/657/EC. This method is considerably robust and allows very dirty samples to be processed. The described MIP procedure is very simple and low-time-consuming, and provides high throughput of the samples examined. This could be used for routine screening and confirmatory analyses as well.     

A cheap gas-liquid-solid method for nanodeposition of iron on the surface of flaky graphite powder

A cheap gas-liquid-solid method to prepare a nanodeposition of iron on the surface of a micrometer-size flaky graphite powder is described. This method is suited not only for spherical, but also nonspherical small substrates. The method is only a one-step process, in which decomposition of iron pentacarbonyl is induced by nitrogen gas in a 90 degrees C reactor. This synthetic route simplifies the operation procedure and manufacturing equipment, and decreases the reaction temperature, compared with conventional liquid-solid-phase methods and gas-solid-phase methods.     

Chemo- and regioselective halogenation of 4-(pyrazol-4-yl)-pyrimidines

A convenient and selective halogenation of 4-(pyrazol-4-yl)-pyrimidines is described herein. This method allows quick access to a diverse set of pyrazolyl-pyrimidine derivatives.     

Corticosteroid Analysis by HPLC-UV Facilitated byv Use of an Injector-Mounted Extraction Column

Abstract

A method for integrating solid phase extraction of corticosteroids from biological samples with normal operation of reversed-phase HPLC is described. This method uses an extraction column mounted in place of the sample loop of a conventional injection valve to separate corticosteroids from some interfering compounds, and to effectively concentrate steroids from dilute samples. Both manual and fully automated chromatographs using this principle are described. A specific application to measurement of corticosterone in a rabbit serum preparation allows routine measurement of as little as 300 pg corticosterone per sample.     

测定心血管紧张素转化酶抑制剂体外抑制动力学的反相HPLC法

报道一种用反相ＨＰＬＣ技术简便、有效地研究心血管紧张素转化酶抑制剂体外抑制动力学的新方法。该法利用马尿酰－甘氨酰－甘氨酸作酶底物，反相ＨＰＬＣ跟踪监测酶解产物马尿酸的浓度随时间变化来研究酶解反应的历程     

A new method for bidimensional analysis of interferometric patterns of liquid films

A new method for bidimensional analysis of interferometric patterns of wetting liquid films obtained with the captive bubble technique is described. This method replaces one-dimensional analysis along various intensity profiles with analysis of one average intensity profile. The advantage is to concentrate the surface characteristics of the whole film image into a single intensity profile.     

Palladium-catalysed reactions of conjugated enyne oxiranes with organoborons: A diastereoselective method of the synthesis of 2,4,5-trienol derivatives

A palladium-catalysed reaction of conjugated enyne oxiranes with organoboron reagents is described. This method allows aryl-substituted vinylallenes containing a hydroxyl group on the allylic position to be synthesized, with good diastereomeric ratios, under mild conditions.     

Spectrophotometric assay of chloramine-T using sulfanilamide

A new spectrophotometric method for the assay of very small amounts of chloramine-T has been developed using sulfanilamide. This method is simple and accurate within the limits described.