摘要:

A method based upon a combination of high performance liquid chromatography (HPLC) and electrospray ionization (ESI) mass spectrometry (MS) for the analysis of phosphorylated peptides in a complex mixture of 14 phosphoenkephalins and their nonphosphorylated analogues is described. A narrow-bore column is directly connected to the ESI interface without the need of a solvent flow-splitter. A full-scan mass analysis in the positive-ion mode is used to provide the total ion current chromatogram and the molecular mass of each eluting component. Selective detection of phosphorylated peptides is achieved by selected-ion recording of the phosphate group marker ion (PO3−) in the negative-ion mode. These two scans are acquired simultaneously on a single injection of the sample. The influence of water clusters on background ion current is also discussed.

ISSN:1082-6076    

DOI:10.1081/JLC-100101757

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Triacylglycerol species (TAG) of oils from five genetically modified soybean varieties were resolved by gradient reversed phase high performance liquid chromatography. The eluting TAG were detected and quantitated without the requirement for TAG response factors or calibration curves for the detector response by an improved evaporative light scattering detector and by a flame ionization detector. The accuracy of the improved light scattering detector for TAG analysis was checked by comparing the absolute error and average absolute error between experimental fatty acid composition obtained by calibrated gas chromatography of the transmethylated soybean oil and the calculated fatty acid composition obtained from the TAG composition of the soybean oil.

ISSN:1082-6076    

DOI:10.1081/JLC-100101758

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The molecular weight distributions (MWDs) of dissolved and residual lignins from different delignification phases during flow-through kraft cooking of birch have been studied. The fundamental characteristics of the isolated lignin samples were evaluated and the lignins were characterised by size exclusion chromatography using lithium chloride/N,N-dimethylacetamide (LiCl/DMAc) not used for isolated lignin samples before. The MWDs of underivatized and acetylated samples were compared with the MWDs of acetylated samples obtained by using tetrahydrofuran (THF) as mobile phase in a similar chromatographic system.

ISSN:1082-6076    

DOI:10.1081/JLC-100101759

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Complex diterpenoid alkaloids of close Rfvalues have been separated by High Performance Centrifugal Partition Chromatography (HPCPC). Model LLB-M (Series 1000) by Sanki Laboratories Inc. was used for these separations. Especially highly polar (on Al2O3) alkaloids which could not be isolated by conventional methods using a solid support, owing to irreversible retention, could be isolated easily as this separation method can be used in the reverse phase mode by careful selection of the biphasic solvent system. The HPCPC instrument was found easy to handle, dependable, applicable to the entire range of polarity of diterpenoid alkaloids, and gave reproducible results. When some of the fractions furnished a mixture of minor alkaloids, the mixture was resolved by a quick separation technique such as separation on a Chromatotron and preparative TLC. In all, eight different mixtures of known as well as crude alkaloidal mixtures were separated and the results are reported here.

ISSN:1082-6076    

DOI:10.1081/JLC-100101760

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The nutritional benefits attributed to fish oils have been the basis for the study of the structural composition of Sardine oil triacylglycerols (TAGs). TAGs were separated reversed-phase high performance liquid chromatography (RP-HPLC) with the result of 65 chromatographic peaks resolved. The problem of identification was avoided by the use of two more chromatographic techniques. Separation of the sardine oil TAGs into fractions by silver-ion thin layer chromatography (TLC) and its subsequent fatty acid analysis by gas chromatography allowed identification of 59 of the 65 chromatographic peaks. From those peaks, the major was trimyristin (MMM), with 8.22 % of the total. Dioleoyl-acyl-glycerol (OPO, OOE), dipalmitoyl-acyl-glycerol (PPO, PPPo), dipalmitoleoyl-acyl.glycerol (PoPoO) and dieicosapentaenoyl-acyl-glycerol (EEP) species were found in important amounts.

ISSN:1082-6076    

DOI:10.1081/JLC-100101761

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Leaves ofTaxus x mediaandTaxus brevifoliawere examined for their potential use as a source of paclitaxel and related taxoids. Various solvent systems were compared for their efficacy in the extraction of paclitaxel, as well as the extraction of contaminating residue. A method of extraction has been developed that enriches paclitaxel by over 500-fold using only potable solvents in combination with solid phase extraction, thus avoiding the use of chlorinated hydrocarbon solvent systems. This solvent system can be used on fresh leaf material, eliminating the need for drying material before extraction, and preventing degradation of the taxoids during the drying process. Using these methods, paclitaxel constituted 0.01 to 0.02% of the dry weight of the leaf tissue fromTaxus x media, and 0.04% from dried leaves ofTaxus brevifolia.

ISSN:1082-6076    

DOI:10.1081/JLC-100101762

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The reproducibility of ion exchange columns was investigated by rigorously evaluating critical chromatographic parameters as well as the performance of these ion exchange columns under various modes of operation. A detailed set of experiments were carried out to determine equilibrium Steric Mass Action parameters, HETP, column dead volume, total ion capacity, and porosity. In addition, the performance of these columns was examined under isocratic, analytical linear gradient, overloaded linear gradient, frontal, and displacement chromatographic conditions. While differences between the two lots were observed with isocratic experiments, the columns exhibited similar behavior under gradient, frontal, and displacement conditions. Furthermore, simulations obtained with the SMA model were shown to predict column performance under linear and non-linear conditions.

ISSN:1082-6076    

DOI:10.1081/JLC-100101763

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Simple and rapid procedures were developed for the quantification of amfepramone hydrochloride and diazepam and mazindol and diazepam in tablets using high performance liquid chromatography (HPLC) with UV detection. These techniques provided conditions for the separation of each active ingredient from the complex matrices of the dosage forms by dilution or extraction in methanol. Isocratic reversed phase chromatography was performed using acetonitrile, methanol, and aqueous 0,1% ammonium carbonate (70:10:20, v/v/v) as a mobile phase, Radial-Pak C18column (100 × 8 mm id, 4μm), a column temperature of 25 ± 1°C and detection at 255 nm. The calibration curves were linear over a wide concentration range (100–1000 μg.mL−1to amfepramone hydrochloride and mazindol and 10–100 μg.mL−1to diazepam) with good correlation factors of 0.9978, 0.9956 and 0.9997 for amfepramone hydrochloride, mazindol, and diazepam, respectively.

ISSN:1082-6076    

DOI:10.1081/JLC-100101764

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

WHI-P154 [4-(3′-bromo-4′hydroxylphenyl)-amino-6,7 di-methoxyquinazoline] is a novel anti-tumor agent with unique cytotoxic activity against human glioblastoma cells (Clin. Cancer. Res. 4:1405-1414, 1998). Further development of WHI-P154 will require detailed pharmacodynamic studies in preclinical animal models. Therefore, we established a sensitive and accurate high performance liquid chromatography (HPLC)-based quantitative detection method for WHI-P154. This method allows the measurement of WHI-P154 levels in plasma, as well as in target human glioblastoma cells. Plasma and cell lysates were extracted with chloroform, dried with nitrogen gas and reconstituted in methanol : water (9:1, v/v).

ISSN:1082-6076    

DOI:10.1081/JLC-100101765

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

A chromatographic method for quantifying the potential antipsychotic compound BIMG 80 (I) was developed and employed for plasma and brain measurements in rats given pharmacologically effective (ED50) doses in the dexamphetamine-antagonism test. The analytical procedure is based on isolation of the compound and the internal standard (haloperidol) from plasma and brain constituents using the LC-18 SPE cartridge, with satisfactory recovery and specificity, isocratic separation on a C18 reversed-phase column coupled with a UV detector set to 225 nm.

ISSN:1082-6076    

DOI:10.1081/JLC-100101766

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor