Wyniki wyszukiwania - Biblioteka Nauki

1

A straightforward electrospray ionization high resolution mass spectrometry method for underivatized long chain polysaccharides

100%

Ghiulai R. M. , Sarbu M. , Ilie C. , Zamfir A. D.

Open Chemistry

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2015

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tom 13

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nr 1

EN

Structural analysis of long chain polysaccharides by electrospray ionization mass spectrometry (ESI-MS) is challenging since these molecules do not contain readily ionizable groups. Their mass spectra are dominated by singly charged ions, limiting the detection of high molecular weight species. Derivatization can enhance ionization, but analyte loss on purification decreases sensitivity. We report a method based on nanoESI-MS and MS/MS by collision induced dissociation (CID) for underivatized long chain polysaccharides. The procedure was tested on underivatized polydisperse dextrans (average molecular weight 4,000) at 2.6 kV ESI voltage and CID MS/MS at energies between 30-60 eV. 113 ions corresponding to species from Glc2 to Glc35 were detected. Ions at m/z 1,409.48, 1,107.35 and 1,438.47, assigned to [G17+2Na]2+,[G20+H+Na+K]3+ and [G35+2H+Na+K]4+, were sequenced and characterized by MS/MS. The component containing 35 Glc repeats is the longest polysaccharide chain detected by ESI-MS and structurally analyzed by MS/MS without prior derivatization and/or separation.

2

Spektrometria mas - uniwersalna technika analityczna

89%

Czerwicka M. , Kumirska J. , Stepnowski P.

Laboratorium - Przegląd Ogólnopolski

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2012

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tom nr 5-6

20--22

PL

Spektrometria mas jest jedną z najpopularniejszych technik analitycznych. Umożliwia ona analizę jakościową i ilościową zarówno prostych związków, jak i wysokocząsteczkowych biomolekuł, a dzięki połączeniu spektrometrii mas z technikami chromatograficznymi także analizę skomplikowanych mieszanin. Najważniejsze aspekty tej techniki zostaną zaprezentowane w niniejszej pracy.

EN

Mass spectrometry is one of the most popular analytical technique. It enables quantitative and qualitative analyses of both simple compounds and high-molecular biomolecules. By means of combination of mass spectrometry with chromatographic techniques also analysis of the complicated mixtures is possible. The most important aspects of this technique will be presented in this article.

3

Optimization of Data Acquisition and Sample Preparation Methods for LC-MS Urine Metabolomic Analysis

88%

Skibiński R. , Komsta Ł.

Open Chemistry

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2015

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tom 13

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nr 1

EN

Nowadays, chromatographic methods coupled with mass spectrometry are the most commonly used tools in metabolomics studies. These methods are currently being developed and various techniques and strategies are proposed for the profiling analysis of biological samples. However, the most important thing used to maximize the number of entities in the recorded profiles is the optimization of sample preparation procedure and the data acquisition method. Therefore, ultra high performance liquid chromatography coupled with accurate quadrupoletime- of-flight (Q-TOF) mass spectrometry was used for the comparison of urine metabolomic profiles obtained by the use of various spectral data acquisition methods. The most often used method of registration of metabolomics data acquisition – TOF (MS) was compared with the fast polarity switching MS and auto MS/MS methods with the use of multivariate chemometric analysis (PCA). In all the cases both ionization mode (positive and negative) were studied and the number of the identified compounds was compared. Additionally, various urine sample preparation procedures were tested and it was found that the addition of organic solvents to the sample noticeably reduces the number of entities in the registered profiles. It was also noticed that the auto MS/MS method is the least efficient way to register metabolomic profiles.

4

Validated stability-indicating HPTLC method for cefixime and azithromycin with preparative isolation, identification, and characterization of degradation products

75%

Gawande V. T. , Bothara K. G. , Satija C. O.

Acta Chromatographica

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2018

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tom Vol. 30, no. 4

212--218

EN

Stability-indicating High-Performance Thin-Layer Chromatography (HPTLC) method for simultaneous estimation of cefixime trihydrate and azithromycin dihydrate was developed. Both the drugs were subjected to different stress conditions recommended by International Conference on Harmonization (ICH) guideline Q1A (R2). Forced degradation was carried out for hydrolytic, oxidative, photolytic, and thermal degradation conditions. Cefixime was susceptible for degradation under all stress conditions showing four degradation products (CI–IV). However, azithromycin formed only one degradation product (AI) under acid hydrolysis. Aluminum plates precoated with silica gel 60F254 were used as the stationary phase while mixture of ethyl acetate–methanol–acetone–toluene–ammonia (1:5:7:0.5:0.5, v/v) was used as mobile phase. Detection wavelength used was 235 nm for CEFI and CI–IV. AZI and AI were detected by post development derivatization, spraying with sulfuric acid–ethanol (1:4, v/v) followed by heating at 100 °C for 5 min. Degradation products were isolated by preparative HPTLC and characterized by MS/MS. The developed method was validated for linearity, precision, accuracy, specificity, and robustness and has been successfully applied in the analysis of these drugs in tablet dosage form.