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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Rotating-disk thin-layer chromatography /

DuPont, Deborah Louise. January 1980 (has links)
Thesis (M.S.)--Ohio State University, 1980. / Includes bibliographical references (leaves 100-104). Available online via OhioLINK's ETD Center
2

An investigation into some aspects of the thin layer chromatographic assay of Pregnanediol with emphasis on the suitability of this method as a clinical laboratory routine

Paton, L T January 1969 (has links)
Pregnanediol (5B Pregnane- 3⋉- 20⋉- dial) is the chief urinary metabolite of progesterone, and as such is important in that variations in its concentration reflect variations in progesterone secretion. Estimations of pregnanediol concentration are therefore of considerable interest to the obstetrician and gynaecologist. Pregnanediol was first identified in the urine of pregnant women in 1929 by Marrian. Nearly ten years later Venning developed a method by which the glucuronic acid ester of pregnanediol could be extracted from the urine and its concentration gravimetrically determined. Numerous variations of the Venning theme were published in the next few years, each being claimed by its authors to be an improvement on the original. Most of these involved the estimation of the conjugated form, and it was a while before the advantage of estimating the hydrolysed aglycone was realized. Hydrolysis, when it was practised, resolved itself into two methods - namely, hydrolysis by heating the urine with a mineral acid, and enzymic hydrolysis by incubation with beta-glucuronidase. Acid hydrolysis, while producing a less clean hydrolysate, is more rapid and convenient than enzyme hydrolysis, and is used in the Klapper method which is presently the most widely used method in clinical studies. Klapper employs a double chromategraphic column separation of pregnanediol followed by colorimetric evaluation. Variations of Klapper's method have also appeared and not a few investigators have published comparisons of the various methods. Klapper himself compared his method to certain other methods and concluded that his was definitely superior. Of the accuracy of the Klapper method there is no doubt. Subsequent methods have proved more sensitive, but in terms of practicability Klapper's is the method of choice. As was pointed out with some complacency, "practicability is most satisfactory, one technician readily performing some twenty determinations in one week." In contrast to the flood of criticisms, comparisons, variations, claims and counter-claims which accompanied the publication of the abovementioned methods, the thin layer chromatographic method perfected by Waldi attracted very little attention. It is very much more rapid than all other existing techniques, is very sensitive, specific and of acceptable accuracy. In an attempt to ensure its usefulness for clinical and medical research laboratories, the Waldi method has been marketed in 'kit' form. It is intended primarily as a diagnostic aid in establishing pregnancy, and as such it might have enjoyed considerable application had it not been for the advent of the immunological method of pregnancy diagnosis which is very much more rapid. Nevertheless, the Waldi method, used purely as a means of assessing the pregnanediol content of the urine is extremely useful, and it is the purpose of this investigation to establish this usefulness, especially with respect to routine clinical investigations. The validity of some diagnoses which are based on pregnanediol assay results, is also investigated. As it is impossible to explain the significance or usefulness of a pregnanediol assay without first explaining the functions of progesterone, some time and space must be expended in a brief description, firstly, of the role played by progesterone in the phenomenon of the menstrual cycle, and secondly, of its vital importance in pregnancy. It must be realized that progesterone is only one of the many hormones involved in these events, but, in order to limit the introduction of extraneous detail, no mention is made of the other hormonal participants except when necessary for the understanding of the whole. It may be mentioned here that much of the evidence that was used for the elucidation of the functions and origins of progesterone, was derived from studies of its metabolite, pregnanediol.
3

In situ analysis of thin layer chromatography plates using an imaging detector /

Gianelli, Mary Lucille. January 1981 (has links)
Thesis (Ph. D.)--University of Washington, 1981. / Vita. Bibliography: leaves [131]-135.
4

A comparative thin layer chromatography study of different brands of five herbal remedies

Urbani, Carla 29 February 2008 (has links)
ABSTRACT The belief that herbal remedies are less invasive on the human body than conventional medicine and the return of the consumer to a more natural lifestyle, has led to the development of a multitude of remedies, with many different uses. Because the use of these herbal remedies has increased drastically in the last decade, it is essential that the quality and efficacy of these products are well regulated. One of the objectives in this study includes the investigation of the presence of marker metabolites in five herbal remedies, namely Serenoa repens, Silybum marianum, Hypericum perforatum, Echinacea purpurea and Gingko biloba. Although most of the brands tested contained the active ingredients assayed for, a few exceptions were found. However, because this study used only thin layer chromatography for analysis of products, verification of these results should be obtained using other more modern methods for example high pressure liquid chromatography. Four brands of Serenoa repens were selected and assayed for the presence of -sitosterol. All four brands tested indicated the presence of -sitosterol. Five brands of Hypericum perforatum were selected and assayed for the presence of hypericin, rutin and chlorogenic acid. Four of the five products tested indicated the presence of hypericin, while three of five products indicated the presence of rutin and chlorogenic acid. Five brands of Echinacea purpurea were selected and assayed for the presence of -sitosterol, chlorogenic and caffeic acid. Three of the five products indicated the presence of -sitosterol, while only one of the five products contained chlorogenic acid. Caffeic acid was present in 3 of the 5 products. Seven brands of Gingko biloba were selected and assayed for the presence of rutin and bilobalide. Five of the seven products indicated the presence of rutin and bilobalide. Four brands of Silybum marianum were selected and assayed for the presence of both taxifolin and sylibin. Only two of the four products contained both taxifolin and silybin. The second objective of this study is to provide a literature review of the five herbal remedies mentioned above. Amongst the topics discussed were uses of these plants, evidence from studies conducted, chemistry and mechanism of action of the active molecules contained in the plants.
5

Separation and detection of cellooligosaccharides on cellulose thin-layer chromatography

Sookavatana, Narumon 11 June 2001 (has links)
Linear oligosacchardies of 1,4 linked β-D-glucopyranose are commonly referred to as cellodextrins (CD) or cellooligosaccharides (CO). They are of interest to those working in disciplines involving cellulose chemistry because they are often used as model substrates for cellulose itself. They are of interest to food scientists and nutritionists because they are easily incorporated into foods as non-digestible oligosaccharides, a category of food ingredients that is thought to be beneficial lo human health. The intent of the research presented in this thesis was to evaluate the potential of using cellulose supports for the chromatographic separation of soluble CDs differing in their degree of polymerization (DP; a numerical value indicating the number of glucose substituents per molecule). Soluble CDs range in DP from 2 to 8. Thin layer chromatography (TLC), using cellulose-coated TLC plates, was used as a model chromatographic system. Mixed CD preparations, containing CDs ranging in DP from 2 to 8 were prepared by incomplete acid-catalyzed hydrolysis of cellulose. The DP profiles of the different CD preparations were qualitatively demonstrated by TLC using silica-coated plates, an organic solvent-based mobile phase, and a standard carbohydrate visualizing reagent (p-anisaldehye in sulfuric acid). CD-preparations were then chromatographed on cellulose-coated TLC plates. Visualization of the chromatographed CDs was accomplished using a silver nitrate-sodium hydroxide reagent system, a reducing-sugar visualizing reagent. The silver nitrate-sodium hydroxide system was found to be the most appropriate, based on detection limits, simplicity and safety, of the several visualization reagents tested. Eight different mobile phases, all aqueous-based, were tested as potential solvents for the resolution of CDs, differing in DP, on cellulose-coated tlc plates at room temperature. The optimum solvent was found to be 60% ethanol/40% water. This solvent clearly resolved CDs of DP 3, 4 and 5. CD preparations chromatographed with the same mobile phase, but with silica-coated TLC plates, were not resolved. These combined results suggest that the TLC system with the cellulose stationary phase behaves similar to an affinity system, since silica and cellulose are both relatively hydrophilic stationary phases (i.e. both systems are typically considered examples of normal phase adsorption chromatography). The results further illustrate that cellulose supports have potential for use in the preparation of CDs of defined DP. / Graduation date: 2002
6

Planar chromatography coupled with mass spectrometry

Mullis, James Onis, Jr. 12 1900 (has links)
No description available.
7

Thin-layer gel-filtration studies of adenosine deaminase in normal and pathological human sera

Frazier, Ronald Burdette January 1980 (has links)
Previous studies of serum adenosine deaminase have neglected consideration of the two molecular forms of this enzyme that exist in human tissues. The purpose of this study was to survey the distribution of these forms in normal and pathological human sera. Both molecular forms were present in normal serum, though the small form predominated. This form also predominates in lymphocytes, erythrocytes, and in tissues with high specific activity of this enzyme. The ratio of the two forms is different for plasma and serum and can change with sample storage. The activity of the small form varied over a wider range than the activity of the large form in normal serum. Many pathological samples showed an altered distribution of the two forms. This study demonstrates the potential usefulness of serum forms of adenosine deaminase for distinguishing some pathological conditions.
8

Cation analysis by thin-layer chromatography and reflectance spectroscopy

Zaye, David F January 1968 (has links)
Typescript. / Thesis (Ph. D.)--University of Hawaii, 1968. / Bibliography: leaves [80]-87. / xi, 87 l illus., tables
9

Reactions of alcohols and organophosphonates on tungsten trioxide epitaxial films /

Ma, Shuguo, January 2003 (has links) (PDF)
Thesis (Ph.D.) in Chemistry--University of Maine, 2003. / Includes vita. Includes bibliographical references (leaves 138-149 ).
10

Reactions of Alcohols and Organophosphonates on Tungsten Trioxide Epitaxial Films

Ma, Shuguo January 2003 (has links) (PDF)
No description available.

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