Quantitative Analysis and Separation of Chiral (S)-Ethyl 3-Hydroxyglutarate in Bioconversion Mixtures by LC and TLC

A convenient ion-pair LC procedure was firstly established for rapid analysis of ethyl 3-hydroxyglutarate (3-EHG) in an enzymatic-hydrolysis mixture, and the detection limit was as low as 0.45 μmol L^?1; high repeatability was achieved with intra-day (n = 5) and inter-day (n = 5) relative standard deviation (RSD) values of 1.56 and 2.38%, respectively. The good linearity was established for 3-EHG concentration in the broad range from 0.005 to 0.30 mol L^?1, with a coefficient (r) of 0.9992. (S)- and (R)-3-EHG were separated by normal-phase LC after simple derivatization with (R)-(+)-phenylethanamine, ee value (≥95%) of 3-EHG prepared by Lipase B catalyzed hydrolysis of diethyl 3-hydroxyglutatate (3-DHG) was determined after optimization of the mobile phase, and the RSD was 0.75% (n = 9) for repeatability. The results showed that the above methods were highly reproducible and reliable for analysis and separation of (S)-3-EHG from bioconversion mixture.     

Quantitative Analysis of Phases Formed During The Oxidation of Covellite (CuS)

A sample of covellite of particle size 45–90 μm was heated in air at 20°C min^–1 in a simultaneous TG-DTA apparatus. The phase compositions of the products at various temperatures were determined quantitatively by XRD and FTIR. By 500°C, 5.8% of Cu₂ O had formed, and this increased to a maximum of 44.8% at 585°C after which it decreased to zero by 750°C. 10% of CuO had formed by 680°C, and then steadily increased to 83.6% at 1000°C. 5.9% of CuO⋅CuSO₄ was found at 610°C, and increased to a maximum value of 79% after which it decomposed completely by 820°C. This revised version was published online in July 2006 with corrections to the Cover Date.     

呋喃丹的薄层扫描定量分析研究

采用双波长反射吸收薄层扫描法对呋喃丹进行了定量分析方法的研究。方法的线性范围为2~200μg,线性相关系数为0.997;呋喃丹的检出限为0.3μg,回收率为96.94%~100.38%,相对标准偏差为1.73%。本方法快速、简单、易行。     

Determination of Allantoin in Drug Preparations by Quantitative High Performance TLC

Abstract

A densitometric TLC method was developed for the quantification of allantoin in creams and suppositories used to treat vaginal infections. Allantoin was extracted with water at elevated temperature, diluted to a known volume, and separated by HP silica gel TLC. Allantoin was detected by spraying with p-dimethylamine-benzaldehyde reagent. The absorption of standards and samples was compared by in situ scanning. Recoveries of allantoin from authentic samples ranged from 96–102%, except for one sample that assayed high. The accuracy of the method was demonstrated by standard addition analysis of this sample.     

薄层原位荧光扫描测定锗-132制剂中倍半氧双羧乙基锗含量的研究

本文报道由作者建立的薄层色谱法,样品在硅胶薄层板上展开后,以苯芴酮显色,再在碘钨灯下照射可使锗-132衍生成荧光化合物,从而可用原位荧光扫描(外标法)定量,已用于倍半氧双羧乙基锗(锗-132)原料和制剂的含量测定及稳定性研究。经3批原料、9批注射液、3批口服液样品的222个测试数据统计,C.V.值为2.29%,同板的C.V.值为1.5%～2.7%(n=7～10);加样回收率101.5%,最低检出限为0.12μg。     

Determination of Sulfanilamide and Sulfisoxazole in Drug Preparations by Quantitative High Performance TLC

Abstract

A densitometric TLC method was developed for quantification of sulfanilamide and sulfisoxazole in creams, supppositories, and tablets. The sulfas were extracted into acidic ethanol, diluted to an appropriate volume, and separated by silica gel HPTLC. The fluorescence quenching of the sulfa zones in samples and standards was compared by in situ scanning. Recoveries of the drugs from authentic samples ranged from 96–105%. Recoveries from products with old expiration dates were low. Identity of the sulfa drugs in products was confirmed by application of fluorescamine and Bratton-Marshall detection reagents.     

Analysis of Analgesic Tablets by Quantitative High-Performance Reversed Phase TLC

Abstract

Aspirin, phenacetin, and caffeine in two commercial analgesic tablets were determined by scanning of fluorescence-quenched zones after separation on high performance TLC plates. Assays for the components ranged from 100 to 88% of label values, and agreement between duplicate samples was better than 5%. Use of phenacetin as an internal standard for determination of aspirin and caffeine was not advantageous. The analysis serves well as an introduction to quantitative TLC in undergraduate laboratory courses.     

原油中三芳甾烃的色谱质谱定量分析

三芳甾烃是原油芳烃组分中的常见化合物,其色谱质谱分析结果对寻找油气有着重要的意义.以往原油中芳烃色谱质谱分析大多忽略了各三芳甾烃化合物的绝对含量,而仅得出各化合物的相对量,使三芳甾烃的应用受到了限制.我们采用人工合成的二氘代化合物d2C28三芳甾烃加入原油中作内标,进行三芳甾烃的色谱质谱定量分析,该内标化合物是将原油中自然存在的1种C28三芳甾烃化合物进行氘代反应,合成得到的d2C28三芳甾烃与原油中的三芳甾烃系列化合物有着相似的结构和质谱分裂特征,并在色谱质谱分析时与原油中的化合物不产生共流.该定量分析方法可以为油气勘探提供更多的信息.     

The Effect of Secondary Chromatography on Quantitative TLC

Most of TLC analysis are performed in the UV and visible spectral region by measuring reflectance with a slit-scanning densitometer or a CCD camera (1-3). However, such measurements are restricted only to the surface of the TLC plate and do not take into account the vertical sub-surface concentration distribution governed by secondary chromatography (4-7) within the sorbent. It is therefore important to investigate effects connected with secondary chromatography in order to reveal their origin, and to. estimate their impact on the results of TLC measurements and their reproducibility.     

Synthesis and Reactivity of Intermediates Formed in the T4 RNA Ligase Reaction

Abstract

T₄ RNA ligase can be used efficiently for the synthesis of 3′-5′ phosphodiester linkages between oligo-nucleotide blocks if the intermediate adenylated donor oligo-nucleotide is used. These adenylated oligonucleotides can be prepared using phosphorylating reagents activated by 1-hydroxybenzotriazole.     

Determination of Pentachlorophenol Residues in Tallow by Quantitative TLC

Abstract

A TLC method is described for screening and quantification of PCP in tallow. PCP is extracted and cleaned up by alumina column chromatography, and is determined by preadsorbent silica gel TLC with silver nitrate detection and densitometric scanning. The detection limit of the analysis was 0.50 ppm in tallow. Recoveries varied from 97.9 to 103% over the fortification range of 1 to 20 ppm. The CV of the analysis was 6.2% .     

Determination of Reactive Intermediates During Anodic Oxygen-transfer Reactions at Lead Dioxide

IntroductionSincethepastdecade ,electrochemicalmethodsforelectrosynthesis ,wastewatertreatmentandorgan iccompounddeterminationhavebeenwidelydevel oped[1— 6 ] .Thebasicprincipleisthatorganicsub stancesareelectrochemicallyoxidizedintothedesiredproducts.However ,inmanycasesthedirectoxida tionoforganicspeciesinanaqueoussolutionatasim plemetaloracarbonelectrodeisnotpossiblebecausethehighpotentialsrequiredfortheoxidationoforgan iccompoundsusuallyresultinoxygenevolution .Therefore ,theproperchoiceof…     

TLC Method for Quantitation of Methylenedioxyphenylacetone and its Derivative Formed in a Resin-Added Bioreduction Process

JPC – Journal of Planar Chromatography – Modern TLC -     

Simultaneous Densitometric TLC Analysis of Atorvastatin Calcium and Fenofibrate in the Bulk Drug and in Pharmaceutical Formulations

JPC – Journal of Planar Chromatography – Modern TLC - The combination of atorvastatin calcium and fenofibrate is used for treatment of atherosclerotic vascular diseases. A simple,...     

Quantitative Ion-Exchange TLC of p-Hydroxybenzoic Acid in the Presence of Preservatives

JPC – Journal of Planar Chromatography – Modern TLC - Rapid separation of p-hydroxybenzoic acid from methyl p-hydroxy-benzoate, ethyl p-hydroxybenzoate, propyl p-hydroxybenzoate,...     

Quantitative determination of iron and copper in cotton material by TLC

Summary A TLC method for the separation of quantitative determination of copper and iron in cotton material is described. The optimal solvent system is 9:2:1 (v/v), ethanol-nitric acid-hydrochloric acid and the locating reagent is Na-diethyldithiocarbamate. Regression analysis shows that the most precise results can be obtained for the concentration range of 0.0400–0.0800 mg/ml of iron and copper.     

薄层扫描法测定利喉乐含片中没食子酸的含量

应用薄层扫描法测定了利喉乐含片中没食子酸的含量。以甲苯－醋酸乙酯－甲酸（Ｖ甲苯∶Ｖ醋酸乙酯∶Ｖ甲酸＝３∶５．４∶０．６）为展开剂,１０ｇ／ＬＦｅＣｌ３显色后,用Ｃｓ－９２０薄层扫描仪扫描,扫描波长为５２０ｎｍ。没食子酸在１．２４～６．２０μｇ之间线性关系良好,该法的加样回收率为９５．９３％,板内精密度为２．７８％,板间精密度为３．３０％,为利喉乐含片的质量控制提供了一种简便而准确的含量测定方法     

Determination of Content and Impurities of Antitumor Drug Carboplatin by TLC Scanning

Content and impurities of antitumor drug Carboplatin have been determined by thin layer chromatography(TLC) scanning. The results of TLC are similar to ones of liquid chromatography, so a new,easy and available method determining content and impurities of antitumor drug Carboplatin that has been found.     

Determination of Aminacrine Hydro-Chloride in Drug Preparations by TLC with Fluorescence Densitometry

Abstract

A densitometric TLC method was developed for quantification of aminacrine hydrochloride in creams, jellies, and suppositories. Aminacrine was extracted into acidic ethanol, diluted to a known volume, and separated by high performance silica gel TLC. The fluorescence of aminacrine zones in samples and standards was compared by in situ scanning. Recoveries of aminacrine from authentic samples ranged from 95.4 to 103.4%.     

Quantitative TLC determination of chlorophylls in spruce needles under mild pollution conditions

Summary The quantitative determination of chlorophyll a and chlorophyll b was by densitometric scanning using cellulose layers. The chlorophyll content of plants ofPicea abies stressed with an anionic detergent was compared with that of a control group. After two years of treatment the chlorophyll content had decreased without the appearance of any visible injury. TLC provides a rapid and simple method for monitoring vegetation damage.