摘要:

AbstractThe literature on the use and theory of silver(I) complexation (argentation) chromatography is reviewed. Apolar isomeric alkenes, for example numerous terpenes and fatty acids, can be well resolved by means of high pressure liquid chromatography on cation exchange materials coated with silver(I) ions, but unfortunately the mechanism on which these separations are based is not fully understood. As part of an attempt to provide a predictive model for the separation of volatile alkenes, the retention of more than 40 C2‐C10 olefins besides a number of C14‐pheromones and volatile terpenes is given and the results discussed. The separation is mainly governed by the type and number of double bonds (isolated, conjugated or aromatic), their steric accessibility (number and size of substituents) for complexation with silver(I) ions, the relief of inherent strain upon complexation and electron donating or withdrawing groups, or polar groups close to the double bond. Polar groups such as hydroxyls also complex weakly with silver. Other functional groups, including carbonyls, and the overall polarity of the solute play only a minor role. Similarly most solvents have only a limited influence on the selectivity and speed of separation, and function more as a transportation medium as in gas chromatography. A comparative model which gives semi‐quantitative estimations of the retention time of most volatile olefins in methanol is presented. Substituent parameters (Ags) which quantitatively forecast the influence of different alkyl side chains are part of this

ISSN:0958-0344    

DOI:10.1002/pca.2800060102

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY

摘要:

AbstractSodium dodecyl sulphate and mercaptoethanol are commonly used for extraction and solubilization of proteins, but these substances interfere with previously reported methods for the quantitation of small amounts of protein. In order to overcome this difficulty, a method has been developed for assaying small quantities of protein by (i) spotting the protein solution on a polyvinylidene difluoride membrane, (ii) staining the membrane bound protein with Coomassie Blue, (iii) destaining, and (iv) determining the optical density of the stained membrane by laser‐based scanning. The determination of proteins in conifer foliage by this method is describe

ISSN:0958-0344    

DOI:10.1002/pca.2800060103

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY

摘要:

AbstractA sensitive method has been developed for the simultaneous determination of S‐adenosyl‐L‐homocysteine (SAH) and S‐adenosyl‐L‐methionine (SAM) in a variety of plant tissues. Samples were extracted in acid and the extracts cleaned up and concentrated by a combination of partitioning with diethyl ether and cation exchange chromatography using phosphocellulose paper. After elution from the phosphocellulose paper with a minimal volume of 6M HCI, SAM and SAH were quantified by ion‐pair reversed phase high performance liquid chromatography with UV detection at 257 nm. Recoveries were monitored using a spike of [14C]‐SAM and were typically between 30 and 40%. In alfalfa, peas and maize the levels of SAM exceeded those of SAH, and in peas levels of SAM were higher in young roots and shoots than in older tissues. When alfalfa cell cultures were treated with a fungal elicitor preparation, the levels of SAM and SAH increased approximately two‐fold over a 12 h period

ISSN:0958-0344    

DOI:10.1002/pca.2800060104

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY

摘要:

AbstractCalystegines are a new group of polyhydroxy nortropane alkaloids that have recently been isolated fromCalystegia sepium.Thin layer chromatography systems have been developed for preliminary screening for these compounds, whilst quantitative analysis has been achieved, following silylation, by gas chromatography (GC) with an internal standard. The reproducibility and accuracy of the quantification method have been examined. The identity of the calystegines was assessed by co‐chromatography with reference samples, by chemical ionization mass spectroscopy (CI‐MS) of isolated calystegines, and by GC‐MS. Cultured roots ofAtropa belladonnawere examined for calyste

ISSN:0958-0344    

DOI:10.1002/pca.2800060105

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY

摘要:

AbstractCharacterization of individual components in plant extracts through classical phytochemical methods is a multi‐step procedure which is both costly and time‐consuming. Also significant amounts of extract are required and detection of minor compounds is frequently not possible. The method described in this work involves direct analysis of crude or prefractioned apolar or medium‐polar extracts by high‐resolution gas chromatography and computerized high resolution gas chromatography‐mass spectrometry, followed by co‐injections of the crude extract with certified standards on capillary columns of different polarities. The effectiveness of the method is illustrated for several species of Polypodiaceae (spores and rhizomes). allowing easy monitoring of compound‐type distributions (e.g. triterpenes) and detection of structures present at trace levels (for example, 22,29,30

ISSN:0958-0344    

DOI:10.1002/pca.2800060106

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY

摘要:

AbstractSaponification and detergent (sodium dodecyl sulphate) solubilization both assisted in the efficient extraction of α‐tocopherol from bell pepper microsomal membranes by solvent. In contrast, solvent extraction by itself exhibited poor extraction capability. In the presence of dithiothreitol, no losses of α‐tocopherol from microsomal membranes were found within 6 h after suspension of membranes; however, in the absence of dithiothreitol, 82% of the initial α‐tocopherol could not be detected within this same time period. α‐Tocopherol losses were not alleviated by nitrogen flushing of the atmosphere of the membrane, although, lower rates of degradation were observed when suspension of microsomal membrane pellets was delayed. Inclusion of water‐soluble antioxidant during short‐term storage of bell pepper microsomal membranes is recommended and similar precautions may be warranted for membranes fro

ISSN:0958-0344    

DOI:10.1002/pca.2800060107

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY

摘要:

AbstractA method has been developed for the rapid and simultaneous extraction and analysis from plant material of 3‐indolylacetic acid (IAA), naphthalene acetic acid (NAA), abscisic acid (ABA) and the cytokinins benzyladenine (BA), zeatin, zeatin riboside, dihydrozeatin, dihydrozeatin riboside, isopentenyl adenine and isopentenyl adenosine. The method involves extraction with 80% (v/v) methanol, pre‐purification of the extracts through reversed phase C18Sep‐Pak cartridges and immunopurification. The separation of the different compounds was accomplished by reverse‐phase high performance liquid chromatography for cytokinins, and by partition with diethyl ether for IAA, NAA and ABA. After methylation of the IAA fraction with diazomethane, quantification of all plant growth regulators (PGRs) was made by immunoassay. The percentage recovery at each step was monitored following the addition of radioactive compounds at the beginning of the process. The final recovery was 68% for IAA, 92% for NAA, 76% for ABA and 75% for BA. The method was applied to the analysis of PGRs in tissues and callus of kiwifruit (Actinidia deliciosaLiang and Fe

ISSN:0958-0344    

DOI:10.1002/pca.2800060108

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY

ISSN:0958-0344    

DOI:10.1002/pca.2800060109

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY

ISSN:0958-0344    

DOI:10.1002/pca.2800060110

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY

ISSN:0958-0344    

DOI:10.1002/pca.2800060111

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY