Current Search: High performance liquid chromatography (x)
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- Title
- High performance liquid chromatographic separation of sedimentary vanadyl porphyrins.
- Creator
- Huang, Xiaoxue, Florida Atlantic University, Baker, Earl W., Charles E. Schmidt College of Science, Department of Chemistry and Biochemistry
- Abstract/Description
-
A method of reversed phase HPLC gradient elution was developed and evaluated for the separation of vanadyl porphyrins. Separation was compared with the result of isocratic elution. It shows that gradient elution method is suitable for vanadyl porphyrin separation and better separation result can be obtained by gradient elution. Gradient elution improves the separation by changing the retention time of different components in the sample mixture and increases the difference of k' (capacity...
Show moreA method of reversed phase HPLC gradient elution was developed and evaluated for the separation of vanadyl porphyrins. Separation was compared with the result of isocratic elution. It shows that gradient elution method is suitable for vanadyl porphyrin separation and better separation result can be obtained by gradient elution. Gradient elution improves the separation by changing the retention time of different components in the sample mixture and increases the difference of k' (capacity factor). Vanadyl porphyrin samples Bakken 6362', Treibs #1 and Treibs #3 were analyzed by this method. Results correlate very well with the results of mass spectrometry analysis of these samples which have been done by some other workers.
Show less - Date Issued
- 1994
- PURL
- http://purl.flvc.org/fcla/dt/15094
- Subject Headings
- Porphyrins, High performance liquid chromatography
- Format
- Document (PDF)
- Title
- HPLC separation and characterization of nickle geoporphyrins.
- Creator
- Zeng, Shaochuan, Florida Atlantic University, Baker, Earl W.
- Abstract/Description
-
HPLC separation of nickel geoporphyrin homologues and isomers has been markedly enhanced by a number of modifications of previously disclosed methods. A general, more efficient and reproducible method has been developed. A C18 3-micron reverse phase column with a programmed gradient binary mobile phase composed of solvent A which is methanol, water and solvent B which consists of methanol modified by the addition of powerful ligand; a consistent ratio of organic salt is added into this...
Show moreHPLC separation of nickel geoporphyrin homologues and isomers has been markedly enhanced by a number of modifications of previously disclosed methods. A general, more efficient and reproducible method has been developed. A C18 3-micron reverse phase column with a programmed gradient binary mobile phase composed of solvent A which is methanol, water and solvent B which consists of methanol modified by the addition of powerful ligand; a consistent ratio of organic salt is added into this solvent system to increase ionic strength of mobile phase. Straightforward HPLC separations of some marine sediment and oil shale extracts (nickel porphyrins) without demetallation have been successfully achieved. Most attention has been focused on Cowboy Gilsonite and Bakken oil-shale. Individual fractions have been collected and analyzed by UV-VIS, NMR, Mass spectrometry. Known compounds were used for co-chromatographic and spectroscopic reference.
Show less - Date Issued
- 1992
- PURL
- http://purl.flvc.org/fcla/dt/14880
- Subject Headings
- High performance liquid chromatography, Porphyrins
- Format
- Document (PDF)
- Title
- Evaluation of alumina-based stationary phases for the separations of proteins and peptides by high performance liquid chromatography.
- Creator
- Raghani, Anil Ratilal., Florida Atlantic University, Haky, Jerome E.
- Abstract/Description
-
Alumina-based stationary phases are evaluated for the separations of proteins and peptides by reversed phase high performance liquid chromatography. Separations are compared to those obtained on a widely-used octadecylsilane (ODS) phase. The separations of peptides on alumina-based stationary phases are found to be superior while separations of proteins are inferior as compared to those found on ODS phase. The superior performance of peptide separations on alumina-based columns is attributed...
Show moreAlumina-based stationary phases are evaluated for the separations of proteins and peptides by reversed phase high performance liquid chromatography. Separations are compared to those obtained on a widely-used octadecylsilane (ODS) phase. The separations of peptides on alumina-based stationary phases are found to be superior while separations of proteins are inferior as compared to those found on ODS phase. The superior performance of peptide separations on alumina-based columns is attributed to lower pore size and uniquely-shaped particles of the alumina. The retentions of peptides and proteins on both alumina and silica-based stationary phases are shown to be governed by hydrophobic interaction mechanisms.
Show less - Date Issued
- 1991
- PURL
- http://purl.flvc.org/fcla/dt/14719
- Subject Headings
- Proteins--Separation, High performance liquid chromatography
- Format
- Document (PDF)
- Title
- A stability study of octadecylalumina columns for use in HPLC.
- Creator
- Goldberg, James Vincent, Florida Atlantic University, Haky, Jerome E.
- Abstract/Description
-
Chromatographic stability studies of an alumina-based reversed phase, ODA, stationary phase were performed. These studies involved monitoring the chromatographic performance of columns packed with the ODA phase after separate, continuous treatment with aqueous solutions of trifluoroacetic acid and sodium hydroxide over a period of several weeks. Chromatographic performance of the ODA columns undergoing treatment with these mobile phases was evaluated by comparing changes in chromatographic...
Show moreChromatographic stability studies of an alumina-based reversed phase, ODA, stationary phase were performed. These studies involved monitoring the chromatographic performance of columns packed with the ODA phase after separate, continuous treatment with aqueous solutions of trifluoroacetic acid and sodium hydroxide over a period of several weeks. Chromatographic performance of the ODA columns undergoing treatment with these mobile phases was evaluated by comparing changes in chromatographic capacity factors, resolutions, plate numbers, and peak asymmetries of a test mixture consisting of uracil, phenol, aniline, methyl benzoate, m-toluidine, N,N-dimethylaniline, and toluene. The results indicate that the alumina-based ODA phase is stable under acidic conditions (pH 2--3) and exceptionally stable to chemical degradation under alkaline conditions (pH ∼ 11).
Show less - Date Issued
- 2000
- PURL
- http://purl.flvc.org/fcla/dt/12681
- Subject Headings
- Chromatographic analysis, High performance liquid chromatography
- Format
- Document (PDF)
- Title
- Investigation of perfluoroalkyl bonded alumina-based stationary phases for reversed phase high performance liquid chromatography applications.
- Creator
- Mannschreck, Tina Marie, Florida Atlantic University, Haky, Jerome E.
- Abstract/Description
-
The general chromatographic properties of perfluoroalkyl-bonded alumina-based stationary phases were evaluated by comparing hydrophobicities and selectivities to octadecyl-bonded silica phases. Potential applications for the perfluoroalkyl-bonded alumina-based stationary phases were also investigated by analyzing octapeptide mixtures as well as separations which employed totally aqueous mobile phases. The fluorinated alumina-based stationary phases investigated in this study were found to...
Show moreThe general chromatographic properties of perfluoroalkyl-bonded alumina-based stationary phases were evaluated by comparing hydrophobicities and selectivities to octadecyl-bonded silica phases. Potential applications for the perfluoroalkyl-bonded alumina-based stationary phases were also investigated by analyzing octapeptide mixtures as well as separations which employed totally aqueous mobile phases. The fluorinated alumina-based stationary phases investigated in this study were found to possess different chromatographic properties compared to octadecylsilica columns.
Show less - Date Issued
- 1994
- PURL
- http://purl.flvc.org/fcla/dt/15055
- Subject Headings
- Chromatographic analysis, High performance liquid chromatography
- Format
- Document (PDF)
- Title
- Investigation of dynamically coated alumina stationary phases for reversed-phase high-performance liquid chromatography.
- Creator
- Ferguson, Veronica, Florida Atlantic University, Haky, Jerome E.
- Abstract/Description
-
Dynamically coated alumina (DCA) was prepared by pumping mobile phase containing methanol and concentration of 10mM Sodium Lauryl Sulphate (SLS), an anionic surfactant prepared in water, through a bare alumina column. The mechanism of separation of a test mixture were characteristic of reversed phase chromatography as evident in the decreased retention time as the percentage of methanol increased. However, the effects of changing the pH of the mobile phase on retention of solutes were...
Show moreDynamically coated alumina (DCA) was prepared by pumping mobile phase containing methanol and concentration of 10mM Sodium Lauryl Sulphate (SLS), an anionic surfactant prepared in water, through a bare alumina column. The mechanism of separation of a test mixture were characteristic of reversed phase chromatography as evident in the decreased retention time as the percentage of methanol increased. However, the effects of changing the pH of the mobile phase on retention of solutes were different than that expected in reversed phase separations, indicating the presence of another retention mechanism. Excellent resolutions, peak shapes and peak symmetries were obtained using the DCA conditions and were comparable to similar separations performed on an ODA (octadecylalumina) column. Comparisons of retentions of a variety of organic compounds on DCA with those of commercial ODS (octadecylsilica) and ODA phases were also performed.
Show less - Date Issued
- 1999
- PURL
- http://purl.flvc.org/fcla/dt/15673
- Subject Headings
- High performance liquid chromatography, Aluminum coating
- Format
- Document (PDF)
- Title
- High performance liquid chromatographic properties of reversed phase alumina.
- Creator
- Vemulapalli, Shobha, Florida Atlantic University, Haky, Jerome E.
- Abstract/Description
-
The chromatographic properties of Octadecylsilica (ODS), Octadecylalumina (ODA), Polybutadiene coated alumina (PBD), Styrene-divinylbenzene copolymer (ACT-1) were investigated to evaluate Octanol-Water partition coefficient, log P, using a correlation method of High Performance Liquid Chromatographic (HPLC) capacity factor, k', and literature partition coefficient values. This study revealed the superior chromatographic characteristics of ODA material and its potential for the evaluation of...
Show moreThe chromatographic properties of Octadecylsilica (ODS), Octadecylalumina (ODA), Polybutadiene coated alumina (PBD), Styrene-divinylbenzene copolymer (ACT-1) were investigated to evaluate Octanol-Water partition coefficient, log P, using a correlation method of High Performance Liquid Chromatographic (HPLC) capacity factor, k', and literature partition coefficient values. This study revealed the superior chromatographic characteristics of ODA material and its potential for the evaluation of log P values of organic compounds, in particular, bases. The log P(HPLC) values evaluated using the log k'-log P regression equation obtained from a set of standards on ODA appeared to be accurate. These values matched with the theoretical calculations supporting the accuracy of the HPLC method.
Show less - Date Issued
- 1990
- PURL
- http://purl.flvc.org/fcla/dt/14657
- Subject Headings
- High performance liquid chromatography--Methodology, Liquid chromatography--Methodology, Oxides
- Format
- Document (PDF)
- Title
- Detection and quantification of trace levels of carbaryl and its metabolites from Dendroctonus frontalis Zimmermann.
- Creator
- Zhong, H., Hastings, F. L., Hain, F. P., Harbor Branch Oceanographic Institute
- Date Issued
- 1994
- PURL
- http://purl.flvc.org/FCLA/DT/3319070
- Subject Headings
- Carbaryl, Southern pine beetle, Dendroctonus frontalis, High performance liquid chromatography
- Format
- Document (PDF)
- Title
- Comparison of alkyl-bonded alumina and silica stationary phases for peptide and protein separations by high performance liquid chromatography.
- Creator
- Williams, David Clinton, Florida Atlantic University, Haky, Jerome E.
- Abstract/Description
-
The applicability of a recently developed octadecylalumina (ODA) stationary phase for the preparative separations of proteins and peptides is compared with that of conventional Octadecylsilica (ODS) phases. Chromatographic peak widths, peaks areas, and recoveries of polypeptides were obtained from both types of phases. The ODA phase compares favorably with the ODS phase on small peptides, but exhibits low recoveries on high molecular weight proteins. The results are attributed to the unique...
Show moreThe applicability of a recently developed octadecylalumina (ODA) stationary phase for the preparative separations of proteins and peptides is compared with that of conventional Octadecylsilica (ODS) phases. Chromatographic peak widths, peaks areas, and recoveries of polypeptides were obtained from both types of phases. The ODA phase compares favorably with the ODS phase on small peptides, but exhibits low recoveries on high molecular weight proteins. The results are attributed to the unique fused-microplatelet shape of the ODA particles.
Show less - Date Issued
- 1996
- PURL
- http://purl.flvc.org/fcla/dt/15260
- Subject Headings
- High performance liquid chromatography, Proteins--Separation, Peptides--Separation
- Format
- Document (PDF)
- Title
- Photosynthetic pigment ratios in relation to Photic Flux.
- Creator
- Grant, Cidya S., Louda, J. William, Florida Atlantic University
- Abstract/Description
-
The molar and weight ratios of the photosynthetic pigments of ten algal species were analyzed in an attempt to determine if knowledge of the light field could be used to give better ratios for estimating the chlorophyll a contributed from each algal division to total chlorophyll a or biomass. High performance liquid chromatography (HPLC) is one of the tools used in pigment-based chemotaxonomy for estimating the biomass of algal communities by determining the concentrations of the various...
Show moreThe molar and weight ratios of the photosynthetic pigments of ten algal species were analyzed in an attempt to determine if knowledge of the light field could be used to give better ratios for estimating the chlorophyll a contributed from each algal division to total chlorophyll a or biomass. High performance liquid chromatography (HPLC) is one of the tools used in pigment-based chemotaxonomy for estimating the biomass of algal communities by determining the concentrations of the various chlorophylls and carotenoids. Stable ratios of chlorophyll a: marker pigment are used as multiplying factors for calculating the amount of chlorophyll a contributed from each major algal group to total chlorophyll a. Stable chlorophyll a : marker pigment ratios are not always easy to determine, so light field was investigated as a factor for determining consistently reliable ratios. This data will serve to determine new chlorophyll a: marker pigment ratios, as well as to verify or suggest changes to the existing ratios that are currently being used by our research group. An unknown pigment was isolated from Scytonema sp. grown in higher light fields and the ecological significance of this pigment was assessed.
Show less - Date Issued
- 2006
- PURL
- http://purl.flvc.org/fau/fd/FA00000768
- Subject Headings
- Photosynthetic pigments--Analysis, Marine algae, Plant pigments--Analysis, High performance liquid chromatography
- Format
- Document (PDF)
- Title
- Sex determination of loggerhead sea turtles (Caretta caretta) via hormonal analysis by high performance liquid chromatography.
- Creator
- Botterill, Brooke L., Florida Atlantic University, Milton, Sarah L.
- Abstract/Description
-
Sea turtles have temperature-dependent sex determination, with males being produced at cooler temperatures and females at warmer ones. Thus, sex ratios are often estimated on average nest temperatures, but this is unreliable. Therefore, many studies have begun to look to alternative methods to identify sex ratios. Other methods used to determine sex require hatchling sacrifice or are labor intensive. This study utilized high performance liquid chromatography (HPLC) to investigate correlations...
Show moreSea turtles have temperature-dependent sex determination, with males being produced at cooler temperatures and females at warmer ones. Thus, sex ratios are often estimated on average nest temperatures, but this is unreliable. Therefore, many studies have begun to look to alternative methods to identify sex ratios. Other methods used to determine sex require hatchling sacrifice or are labor intensive. This study utilized high performance liquid chromatography (HPLC) to investigate correlations between steroid hormone levels in hatchling plasma and allantoic fluid, nest temperature and sex. Hatchling sex was determined laparoscopically to ground-truth hormone profiles. No correlation was found between hormones, nest temperature and sex. However, as hormones were readily detectable by HPLC, the technique may be applicable to juvenile or adult turtles with mature profiles.
Show less - Date Issued
- 2005
- PURL
- http://purl.flvc.org/fcla/dt/13284
- Subject Headings
- Sea turtles--Nests--United States, Loggerhead turtle--Breeding, Sex (Biology), High performance liquid chromatography
- Format
- Document (PDF)
- Title
- Hemisynthesis and Characterization of Cyclopheophorbides.
- Creator
- Mortezaei-Rad, Mitra, Florida Atlantic University, Louda, J. William, Charles E. Schmidt College of Science, Department of Chemistry and Biochemistry
- Abstract/Description
-
Cyclopheophorbides absorb light at higher wavelengths (> 670 run) as compared to their precursor pyropheophorbides ( ~ 666 run) and are strong antioxidants. Therefore they could potentially be used as photosensitizers in photodynamic therapy, although this study does not focus on the pharmacology aspect of this class of compounds. The overall goal of this study was to hemisynthesize, purify and characterize certain cyclopheophorbides from both chlorophyll a and b families. The known...
Show moreCyclopheophorbides absorb light at higher wavelengths (> 670 run) as compared to their precursor pyropheophorbides ( ~ 666 run) and are strong antioxidants. Therefore they could potentially be used as photosensitizers in photodynamic therapy, although this study does not focus on the pharmacology aspect of this class of compounds. The overall goal of this study was to hemisynthesize, purify and characterize certain cyclopheophorbides from both chlorophyll a and b families. The known hemisynthesis of 13^2,17^3-cyclopheophorbide a enol was repeated. A major success in the purification process was achieved by utilizing polystyrene divinylbenzene (PS-DVB a.k .a. PRP-1 TM) as the stationary phase in reversed phase flash chromatography. Altering (TMS)2-NNa with (TMS)2-NLi was found to increase yields. 13^2,17^3 -mesocyclopheophorbide a enol was successfully hemisynthesized as a novel compound. Methyl-3-devinyl-3-[1-hexyloxy]ethyl pyropheophorbide a (HPPH-ME), was prepared, purified and molecular characteri zation on the compound was performed. Hemisynthesis ofHPPH-CYCLO from HPPH-ME was attempted, but was unsuccessful. Zinc and copper pyropheophorbide a methyl esters were prepared with the intent of forming of zinc and copper CYCLO. Hemisynthesis of corresponding metalloCYCLO from both insertion of the metal inside the CYCLO core and cyclizations of metal derivatives of pyropheophorbide a methyl ester were unsuccessful. Chlorophyll b was successfully extracted from green algae Chiarella and purified in mg lots (100%) utilizing RP-LPLC and with a binary solvent gradient program. Pheophorbide b methyl ester and pyropheophorbide b methyl ester were made and characterized. Hemisynthesis of CYCLO-b was unsuccessful likely due to the altered reactivity of pyropheophorbide b (vs. -a) methyl ester. To reduce the reactivity, reduction of formyl group of pyropheophorbide b methyl ester with NaBH4 was performed. Still, formation of a CYCLO derivative was not achieved. Chromatographic purification, mass and NMR characterization of CYCLO, mesoCYCLO, HPPH-ME and all precursor compounds are reported. 2D NMR of most of these compounds are reported here for the first time.
Show less - Date Issued
- 2007
- PURL
- http://purl.flvc.org/fau/fd/FA00000872
- Subject Headings
- High performance liquid chromatography, Organometallic chemistry, Organic compounds--Spectra, Organophosphorus compounds
- Format
- Document (PDF)
- Title
- Epiphyte productivity and community structure in conjunction with HPLC pigment analysis.
- Creator
- Singh, Alya G., Florida Atlantic University, Louda, J. William
- Abstract/Description
-
Seagrass meadows in Florida Bay have rapidly declined due to synergistic stresses. The microalgal communities present on the leaves of Thalssia testudinum were studied in the Snake Bight and Whipray Basin areas of Florida Bay. These areas have been the sites of recurrent phytoplankton blooms and this study was aimed at exploring similar effects within the microalgal epiphytic communities. Epiphytometers, or surrogate seagrass, were used to provide a time zero (T0) point which is impossible in...
Show moreSeagrass meadows in Florida Bay have rapidly declined due to synergistic stresses. The microalgal communities present on the leaves of Thalssia testudinum were studied in the Snake Bight and Whipray Basin areas of Florida Bay. These areas have been the sites of recurrent phytoplankton blooms and this study was aimed at exploring similar effects within the microalgal epiphytic communities. Epiphytometers, or surrogate seagrass, were used to provide a time zero (T0) point which is impossible in natural samples. Epiphyte samples were analyzed using HPLC/PDA which provided measurements of standing crop and community structure (>90% diatom). Epiphytometers were found to be excellent tool for monitoring epiphyte productivity on Thalassia. The monitoring of productivity, standing crop and community structure should allow insight into positive and negative effects of water supply changes.
Show less - Date Issued
- 2003
- PURL
- http://purl.flvc.org/fcla/dt/13066
- Subject Headings
- Epiphytes, High performance liquid chromatography, Seagrasses--Florida--Florida Bay, Thalassia--Florida--Florida Bay
- Format
- Document (PDF)
- Title
- Pigment analysis of benthic and pelagic algae in Lake Okeechobee, Florida.
- Creator
- Winfree, Nancy, Florida Atlantic University, Baker, Earl W.
- Abstract/Description
-
Water samples from Lake Okeechobee, Florida have been analyzed in order to relate pigment fingerprints to temporal and spatial variations. Chemical taxonomic identification of predominant photoautotrophs was based on pigment profiles evolved from literature reports and analysis of specific cultures. Carotenoids and chlorophylls were analyzed using high performance liquid chromatography (HPLC) and ultra-violet visible spectra obtained with a photo diode array detector (PDA). Pigments were...
Show moreWater samples from Lake Okeechobee, Florida have been analyzed in order to relate pigment fingerprints to temporal and spatial variations. Chemical taxonomic identification of predominant photoautotrophs was based on pigment profiles evolved from literature reports and analysis of specific cultures. Carotenoids and chlorophylls were analyzed using high performance liquid chromatography (HPLC) and ultra-violet visible spectra obtained with a photo diode array detector (PDA). Pigments were identified by coincident matches of retention time and UV/Visible spectral properties. Chemical taxonomic identification was determined by comparison with known photoautotrophic pigment 'fingerprints'. Experimental results show pigment arrays indicative of chromophytes, chlorophytes and cyanophytes as well as photoautotrophic bacteria present in Lake Okeechobee. The lake was also found to be heterogeneous and dynamic in terms of pigment composition. Major pigment groups changed as a function of location in the lake and as a function of season. A greater pigment diversity was found to exist in the benthos due to the presence of degradation products. HPLC-PDA pigment analysis for chemotaxonomic typing of photoautotrophic communities is attainable and can be used as a rapid viable alternative to microscopic examination of plankton and epiphyte samples. Also, taxonomic typing of organic matter and photoautotrophic communities of sediments, including bacterial populations, can be accomplished using this method.
Show less - Date Issued
- 1996
- PURL
- http://purl.flvc.org/fcla/dt/15261
- Subject Headings
- Plant pigments--Analysis, Photosynthetic pigments--Analysis, Freshwater algae, High performance liquid chromatography, Okeechobee, Lake (Fla)
- Format
- Document (PDF)