University of Macau / Institute of Chinese Medical Sciences

Zirconia is one of the most promising column packing materials for High Performance Liquid Chromatography (HPLC). The perfect HPLC support material should be energetically homogenous, have a high surface area on which different chemical species can reversibly attach and be physically and chemically stable over a wide range of pH, temperature and solvent conditions. Most existing supports do not have all of these properties. This project is also focused on a proteomics study. Zirconia, hafnium oxide and titanium oxide which are some of the more promising materials currently available, can be used for the separation and analysis of phosphorylated proteins. Adenosine triphosphate, Adenosine diphosphate and Adenosine monophosphate were used as prototypes for phosphorylated proteins. Separation, absorption, fluorescence and SEM studies were performed to determine the adsorption of Adenosine phosphates species at a particular pH on Zirconia. Zirconia was also used for the purification of Fibrinogen Growth Factor (FGF) protein, which are a family of growth factors involved in angiogenesis, wound healing, and embryonic development. The sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) technique was used to analyze the off-column purification and separation of this protein. This research suggests that, at acidic conditions, adenosine monophosphate has more favorable absorption on the Zirconia surface. On the other hand, the separation study suggests that basic conditions are more favorable for the absorption of ATP, ADP and AMP when mixed together on Zirconia 500. Furthermore, it was found that Zirconia is a very promising material for the purification of FGF protein.

There are two purposes in this research, one is the development of the new method which can be used for detection and quantification of triarylmethanes in fish tissues. The other is that we confirmed validation and utility of triarylmethanes by the method that is according to Commission Decision 2002/657/EC. Homogenized fish tissues were extracted twice with acetonitrile and defatted with n-hexane. HPLC separation was conducted with the RP-18 column. The mobile phases consisted of 0.5 mM ammonium acetate buffer (pH 3.8, adjusted with acetic acid)¡V ACN (contained 0.1% formic acid) solution. Triarylmethane was determined by LC-ESI-MS/MS in positive mode. The correlation coefficients of calibration curves with triarylmethane in fish tissues were 0.998 ~ 0.999. The decision limits (CC£\) were 0.16 ¡Ó 0.07 £gg/kg(MG), 0.15 ¡Ó 0.04 £gg/kg(LMG), 0.20 ¡Ó 0.13 £gg/kg(CV) and 0.23 ¡Ó 0.12 £gg/kg(LCV), and detection capabilities (CC£]) were 0.20 ¡Ó 0.09 £gg/kg(MG), 0.18 ¡Ó 0.05 £gg/kg(LMG), 0.24 ¡Ó 0.16 £ggkg-1(CV) and 0.29 ¡Ó 0.15 £gg/kg(LCV).

Thesis (M.S.)--Eastern Illinois University, 2009. / Includes bibliographical references (leaves [117]-125).

M. Tech. Chemistry. / Aims to evaluate, compare and modify existing methods and investigate new methods for the qualitative and quantitative determination of melamine. Specific aims were to: evaluate and modify an existing GC-MS15 and HPLC-DAD method16, published by US FDA, for the determination of melamine in pet food and baby milk powder formulae ; develop a novel HPLC fluorescence detection (FLD) method for the determination of melamine in pet food and baby milk powder formulae ; compare these methods to a commercial ELISA detection method for the determination of melamine in pet food samples previously implicated in the poisoning of dogs ; apply NIR spectroscopy with subsequent multivariate analysis to rapidly determine melamine in pet food; and compare the different methods statistically with respect to their analytical performances.

published_or_final_version / Chemistry / Master / Master of Philosophy

In natural dendroflora of Lithuania willow genus (Salix L.) is abundant in species amount. Its bark contains active materials which are known as possessing anti-inflammatory properties since former times. Bark extracts are contained in analgesic as well as antirheumatic preparations. Its therapeutic effectiveness is associated with salicine which turns into salicylic acid. Willow bark is a know phytotherapeutic precursor of aspirin. To use more natural and not synthetic materials in the 21st century the methods for extraction of active materials for medicine are being sought. Thus, the studies on plant groups possessing the most intense anti-inflammatory properties became urgent. The amount of salicin varies among different species. Acording to the European Pharmacopoea, minimal amount of 1,5% of salicin is required in Willow bark. The aim of the study was to investigate salicylates amount variation in willow bark of different Salix species growing in Lithuania. The studies were carried out using the routine methods of pharmacopeia. After extraction analysis was performed by high performance liquid chromatography (HPLC) method. The first step of study was made among 3 samples of each plant, colected at different growing period (1-st year autumn, 2-nd year autumn and 2-nd year spring). Comparison of the quantities of the salicylic derivatives depending upon age of the plant and time of collection shows, that plants at two years of growth and collected in autumn accumulate... [to full text] / Natūralioje Lietuvos floroje gluosnių (Salix L.) rūšys yra plačiai paplitusios. Gluosnio žievė – nuo seno žinoma kaip priešuždegiminiu poveikiu pasižyminti vaistinė augalinė žaliava. Jos ekstraktai įeina į priešreumatinių ir analgezinių preparatų sudėtį. Terapinis veikimas yra susijęs su salicinu, kuris organizme virsta salicilo rūgštimi. Gluosnio žievė yra fitoterapinis aspirino pirmtakas. XXI amžiuje vis didesnis dėmesys krypsta į natūralius, o ne sintetinius preparatus. Tokiu būdu, augalų, pasižyminčių terapinėmis savybėmis tyrimai įgyja didelę reikšmę. Skirtingų rūšių gluosnių žievėje, kaupiamas salicino kiekis skiriasi. Europos farmakopėjoje reglamentuojamas minimalus salicino kiekis yra 1,5%. Šio tyrimo tikslas buvo Ištirti Lietuvoje augančių gluosnio rūšių salicilatų kiekio įvairavimą vaistinėje augalinėje žaliavoje (žievėje). Darbo uždaviniai- atlikti įvairių Lietuvoje augančių gluosnio rūšių salicilatų kiekio analizę, palyginti salicilatų kiekį gluosnio žievėje, atsižvelgiant į augalo amžių bei rinkimo laiką bei įvertinti gautus rezultatus, numatomą terapinį veikimą. Tyrimai atlikti naudojant farmakopėjinius analizės metodus. Žievės ekstraktai buvo tiriami efektyviosios skysčių chromatografijos metodu.Šio tyrimo pirmo etapo metu išanalizuota 12 gluosnių taksonų. Buvo ištirti vienerių ir dviejų metų, taip pat pavasarį ir rudenį rinkti žievės pavyzdžiai. Didesni kiekiai aktyvių medžiagų rasta rudenį ir 2 metų amžiaus gluosnių žievės pavyzdžiuose. Antrajame tyrimo... [toliau žr. visą tekstą]

Using a model system of glycosylated and aglycon standards consisting of rutin and quercetin respectively, and a series of pre-packed solid phase extraction cartridges, including C18 Extra-Clean, DSC-18, DPA-6S, Oasis HLB and Amberlite XAD-2. The experimental findings also showed that use of a commercial hesperinidase preparation, resulted in adequate hydrolysis of the glycosylated standard rutin. Based on these findings, the phenolic compounds and flavonoids from maple sap and syrup were separated using the Amberlite XAD-2 column, where the glycosylated fractions eluted with 60% aqueous methanol solution and the aglycon fractions eluted with a methanol:acetonitrile mixture (1:1, v/v). The recovered glycosylated fractions were subjected to enzymatic hydrolysis using the hesperinidase preparation and the liberated phenolic compounds and flavonoids, as well as the sugar components were analyzed by high-performance liquid chromatography (HPLC).

Comparative high-performance liquid chromatography (HPLC) and gas-liquid chromatography (GC) analyses of selected phenolic and flavonoid standards were developed using a wide range of detectors, including ultraviolet diode-array (UV-DAD) and electrochemical (EC) detectors for HPLC and flame ionization detector (FID) and mass spectrometry (MS) for GC. The results demonstrated that the limits of detection obtained with HPLC-EC analysis were 10 to 500-times higher for phenolic acid standards and 2 to 50-times higher for flavonoid standards than those obtained with the HPLC-UV analysis. HPLC-EC was more sensitive than GC/FID for all investigated standards, especially for vanillin and syringaldehyde. The results indicated that GC/FID/MS analysis of phenolic and flavonoid standards was more efficient than that of HPLC, providing a fast analysis with better resolution and baseline separation of all standards with minimum co-elution. The only co-elution encountered in GC/FID was with coniferol and p-coumaric acids. For HPLC analysis, (-)-epicatechin, caffeic and homovanillic acids were co-eluted at 28.04 min and sinapic and ferulic acids at 34.57 min. Phenolic compounds and flavonoids were extracted from maple sap and maple syrup with ethyl acetate and the recovered compounds were subjected to HPLC and GC analyses. Tentative identification of phenolic compounds and flavonoids in maple sap and maple syrup indicated the presence of protocatechuic acid, hydroxycinnamic acid derivatives, (+)-catechin, (-)-epicatechin, vanillin, coniferol, syringaldehyde, flavanols and dihydroflavonols related compounds. In addition, the identification by GC/MS of protocatechuic acid, vanillin, syringaldehyde, coniferol and p-coumaric acid was made by comparing mass spectrum characteristics of individual peak from total ion chromatogram (TIC) to that of standard compounds. The seasonal variation of selected phenolic compounds and flavonoids present in maple sap and maple syrup was also invest

Three direct interfaces for coupling high performance liquid chromatography (HPLC) with atomic absorption spectrometry (AAS) were developed and optimized for the determination of ionic organolead, organoselenium and organoarsenic compounds. The first all-quartz interface consisted of a thermospray nebulizer and a flame microatomizer in which ionic alkyllead analytes (R$ sb{ rm n}$Pb$ sp{ rm (4-n)+};$ R = CH$ sb3,$ C$ sb2$H$ sb5)$ were atomized by a methanol (from HPLC eluent)-oxygen kinetic flame, and channeled in a quartz tube (atom keeper) mounted into the AAS optical beam. Alternately, the classical electrothermal atomization technique for organolead species (quartz furnace under hydrogen atmosphere) was coupled with a post-column derivatization-volatilization apparatus based on the ethylation of ionic alkylleads by sodium tetraethylborate. The limits of detection provided by these two approaches were 1.0-3.4 ng and 0.10-0.15 ng, respectively. Arsonium ((CH$ sb3) sb3$RAs$ sp+;$ R = CH$ sb3,$ CH$ sb2$CH$ sb2$OH, CH$ sb2$COOH) and selenonium ((CH$ sb3) sb2$RSe$ sp+;$ R = CH$ sb3,$ CH$ sb2$CH$ sb2$OH) species were quantified using a novel HPLC-AAS approach based on a direct coupling of three processes: thermospray nebulization, thermochemical hydride generation using hydrogen gas, and diffuse flame atomization. Direct evidences for the thermochemical hydride generation process was obtained by injecting (CH$ sb3) sb3$SeI and SeO$ sb2$ into the interface and capturing the gaseous end products in liquid chemical traps specific for SeH$ sb2$ and Se(IV). Both analytes were derivatized to SeH$ sb2$ only in the presence of hydrogen in the interface. Reverse- and normal-phase high pressure liquid chromatographic methods were also developed and adapted for the HPLC-AAS analyses of alkyllead, arsonium and selenonium compounds in real samples. The limit of detection of the arsonium and selenonium cations were 7.6-13.3 ng and 31.0-43.9 ng, respectively.