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Sample Preparation Protocol (sample + preparation_protocol)

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Chemistry100%

Selected Abstracts

Analysis of secondary metabolites from eschscholtzia californica by high-performance liquid chromatography

PHYTOCHEMICAL ANALYSIS, Issue 4 2006
Maya Klvana
Abstract A rapid and precise analytical HPLC method has been developed for screening the major benzophenanthridine alkaloids produced by cell cultures of Eschscholtzia californica, namely, sanguinarine, chelirubine, macarpine, chelerythrine and chelilutine. Separation was achieved on a C18 reversed-phase column with gradient elution using acetonitrile and 50 mm phosphoric acid. Detection was performed by both fluorescence (,ex 330 nm, ,em 570 nm) and photodiode array, leading to good selectivity and precision in determining peak purity. A simple and quick sample preparation protocol was elaborated involving a methanolic extraction for the measurement of intracellular concentrations of the alkaloids and a solid phase extraction for their quantification in culture medium. Owing to the non-availability of commercially standards, a method for the purification of chelirubine, macarpine and chelilutine by semi-preparative HPLC was developed. Coupled together, the isolation method and the analytical method were highly reliable for screening the alkaloids of interest produced by E. californica. Copyright © 2006 John Wiley & Sons, Ltd. [source]

Selective imaging of positively charged polar and nonpolar lipids by optimizing matrix solution composition

RAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 20 2009
Yuki Sugiura
Previous studies have shown that matrix-assisted laser desorption/ionization,imaging mass spectrometry (MALDI-IMS) is useful for studying the distribution of various small metabolites, particularly lipids. However, in this technique, selective ionization of the target molecules is imperative, particularly when analyzing small molecules. Since the sample clean-up procedures available for the MALDI-IMS of small metabolites are limited, the tissue sample will contain numerous molecular species other than the target molecules. These molecules will compete for ionization resulting in severe ion suppression. Hence, it is necessary to develop and optimize a sample preparation protocol for the target molecules. In this study, through model experiments using reference compounds, we optimized the composition of the matrix solution used for positively charged lipids in terms of the concentration of the organic solvent and presence/absence of alkali metal salts. We demonstrated that a high concentration of organic solvent in the matrix solution favors the preferential detection of lipids over peptides. The presence of alkali metal salts in the matrix solution was favorable for the detection of polar lipids, while a salt-free matrix solution was suitable for the detection of nonpolar lipids. Furthermore, potassium salts added to the matrix solution caused merging of various lipid adducts (adducts with proton, sodium, and potassium) into one single potassiated species. Using the optimized protocols, we selectively analyzed phosphatidylcholine (PC) and triacylglycerol (TG) with different fatty acid compositions in a rat kidney section. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Application of hyphenated mass spectrometry techniques for the analysis of urinary free glucocorticoids

RAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 18 2009
Angela Cuzzola
Alteration of levels of glucocorticoids in plasma and urine can be related to several diseases. In particular, the determination of endogenous glucocorticoids in urine has been reported to provide information on cortisol and cortisone status, on the activities of steroid hormone enzymes and on glucocorticoid metabolism. In this study, the application of hyphenated mass spectrometry techniques (GC/MS without derivatization and LC/MS) for the simultaneous analysis of free urinary cortisol (F), cortisone (E), tetrahydrocortisol (THF), allo-tetrahydrocortisol (A-THF) and tetrahydrocortisone (THE) was evaluated. A sample preparation protocol by solid-phase extraction, mass spectrometry parameters and chromatographic conditions for both techniques were carefully optimized in terms of extracting phase and solvents, matrix effects, recovery, sensitivity and compound resolution. Baseline separation was achieved for the five underivatized analytes both in GC and LC. The LC/MS/MS technique was more suitable for the analysis of urine samples, being less influenced by matrix effects and showing excellent sensitivity and selectivity. A preliminary application of the reported method for the diagnosis of metabolic diseases was also described. The determination of each analyte in its free form, described for the first time in the paper, offers new perspectives in the application of glucocorticoid analysis for diagnostic purposes. Copyright © 2009 John Wiley & Sons, Ltd. [source]

A suite of tools to analyse and publish 2-DE data

PROTEINS: STRUCTURE, FUNCTION AND BIOINFORMATICS, Issue 23-24 2008
Christine Hoogland Dr.
Abstract Bioinformatics tools may assist scientists in all steps of a typical 2-DE gel analysis workflow, that is, from the description of the sample preparation protocols, going through the gel image analysis and protein identification, to the publication of Internet-ready 2-DE gel databases. This short communication highlights in a single and summarised view, this workflow and the current bioinformatics solutions developed by the Proteome Informatics Group at the Swiss Institute of Bioinformatics. [source]

Analysis of a bioactive , -(1,,,3) polysaccharide (Curdlan) using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

RAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 9 2003
T.-W. D. Chan
This paper focuses on the development of MALDI sample preparation protocols for the analysis of a bioactive , -(1,,,3) polysaccharide, i.e. Curdlan. The crude Curdlan sample was first separated into a low molecular weight water-soluble portion and a high molecular weight water-insoluble portion. The water-soluble portion was analyzed using a standard MALDI sample preparation method developed for dextran analysis. Two low-mass (<4000,Da) polysaccharide distributions differing by 16,Da were observed. For the analysis of the water-insoluble portion, several sample preparation protocols were evaluated using GPC-fractionated samples. A sample preparation method based on the deposition of the analyte solution with a mixture of 2,5-dihydroxybenzoic acid (DHB) and 3-aminoquinoline (3AQ) matrices in dimethyl sulfoxide (DMSO) at elevated temperature of 70°C was found to reliably produce good MALDI spectra. MALDI analysis of the water-insoluble Curdlan portion gave number-average (Mn) and weight-average (Mw) molecular weights and polydispersity of 8000,Da, 8700,Da, and 1.10, respectively. Copyright © 2003 John Wiley & Sons, Ltd. [source]