Lipid profiling analyses from mouse models and human infants.

This protocol outlines a translational lipidomic approach to discover lipid biomarkers that could predict morphometric body and histological organ measurements (e.g., weight and adiposity gains) during specific stages of life (e.

Adaptation of exercise-induced stress in well-trained healthy young men.

What is the central question of this study? Exercise is known to induce stress-related physiological responses, such as changes in intestinal barrier function. Our aim was to determine the test-retest repeatability of these responses in well-trained individuals. What is the main finding and its importance? Responses to strenuous exercise, as indicated by stress-related markers such as intestinal integrity markers and myokines, showed high test-retest variation.

Identification of drug metabolites in human plasma or serum integrating metabolite prediction, LC-HRMS and untargeted data processing.

Background: Comprehensive identification of human drug metabolites in first-in-man studies is crucial to avoid delays in later stages of drug development. We developed an efficient workflow for systematic identification of human metabolites in plasma or serum that combines metabolite prediction, high-resolution accurate mass LC-MS and MS vendor independent data processing. Retrospective evaluation of predictions for 14 (14)C-ADME studies published in the period 2007-January 2012 indicates that on average 90% of the major metabolites in human plasma can be identified by searching for accurate masses of predicted metabolites.

Pre-processing liquid chromatography/high-resolution mass spectrometry data: extracting pure mass spectra by deconvolution from the invariance of isotopic distribution.

Rationale: Mass spectra obtained by deconvolution of liquid chromatography/high-resolution mass spectrometry (LC/HRMS) data can be impaired by non-informative mass-over-charge (m/z) channels. This impairment of mass spectra can have significant negative influence on further post-processing, like quantification and identification.

Methods: A metric derived from the knowledge of errors in isotopic distribution patterns, and quality of the signal within a pre-defined mass chromatogram block, has been developed to pre-select all informative m/z channels.

Analysis of oligosaccharides in lignocellulosic biomass hydrolysates by high-performance anion-exchange chromatography coupled with mass spectrometry (HPAEC-MS).

The carbohydrate composition of lignocellulosic biomass hydrolysates is highly complex. High performance anion exchange chromatography coupled with pulsed amperometric detection (HPAEC-PAD), a widely used method for carbohydrate analysis, provides limited chemical information on the detected peaks. To improve the detection and increase the chemical information of the carbohydrates, HPAEC was coupled with mass spectrometry (MS).

Instrument and process independent binning and baseline correction methods for liquid chromatography-high resolution-mass spectrometry deconvolution.

Setting appropriate bin sizes to aggregate hyphenated high-resolution mass spectrometry data, belonging to similar mass over charge (m/z) channels, is vital to metabolite quantification and further identification. In a high-resolution mass spectrometer when mass accuracy (ppm) varies as a function of molecular mass, which usually is the case while reading m/z from low to high values, it becomes a challenge to determine suitable bin sizes satisfying all m/z ranges. Similarly, the chromatographic process within a hyphenated system, like any other controlled processes, introduces some process driven systematic behavior that ultimately distorts the mass chromatogram signal.

Comprehensive analysis of umami compounds by ion-pair liquid chromatography coupled to mass spectrometry.

Unlabelled: An ion-pair LC-ESI-MS method was developed capable of analyzing various reported umami or umami-enhancing compounds, including glutamic acid and 5'-ribonucleotides. The method was validated using tomato and potato samples and showed overall good analytical performance with respect to selectivity, detection limit, linearity, and repeatability. The method was applied to various tomato samples resulting in concentrations of glutamic acid and 5'-ribonucleotides that were in good comparison with literature.

Analysis of reaction products of food contaminants and ingredients: bisphenol A diglycidyl ether (BADGE) in canned foods.

Bisphenol A diglycidyl ether (BADGE) is an epoxide that is used as a starting substance in the manufacture of can coatings for food-contact applications. Following migration from the can coating into food, BADGE levels decay and new reaction products are formed by reaction with food ingredients. The significant decay of BADGE was demonstrated by liquid chromatographic (LC) analysis of foodstuffs, that is, tuna, apple puree, and beer, spiked with BADGE before processing and storage.

In-depth characterization of prebiotic galacto-oligosaccharides by a combination of analytical techniques.

A commercial prebiotic galacto-oligosaccharide mixture (Vivinal GOS) was extensively characterized using a combination of analytical techniques. The different techniques were integrated to give complementary information on specific characteristics of the oligosaccharide mixture, ranging from global information on degree of polymerization (DP) to the identity and concentration of individual oligosaccharides. The coupling of high-performance anion-exchange chromatography (HPAEC) to mass spectrometry (MS) was determined to be especially suitable to assign the DP of individual oligosaccharides on the basis of their m/z values as well as their quantification using external standards.

Simultaneous determination of endogenous deoxynucleotides and phosphorylated nucleoside reverse transcriptase inhibitors in peripheral blood mononuclear cells using ion-pair liquid chromatography coupled to mass spectrometry.

Nucleoside reverse transcriptase inhibitors (NRTIs) are activated intracellularly to their triphosphate (TP) form, which compete with endogenous deoxynucleotide-triphosphates (dNTP) as substrate for HIV reverse transcriptase. The activity of NRTIs is thus described by the NRTI-TP-to-dNTP ratio in relevant cell types. Therefore, we developed an ion-pair (IP) LC-MS method for the simultaneous analysis of the mono-, di-, and TP forms of NRTIs and endogenous deoxynucleosides in peripheral blood mononuclear cells (PBMC).

Simultaneous quantitative analysis of metabolites using ion-pair liquid chromatography-electrospray ionization mass spectrometry.

We have developed an analytical method, consisting of ion-pair liquid chromatography coupled to electrospray ionization mass spectrometry (IP-LC-ESI-MS), for the simultaneous quantitative analysis of several key classes of polar metabolites, like nucleotides, coenzyme A esters, sugar nucleotides, and sugar bisphosphates. The use of the ion-pair agent hexylamine and optimization of the pH of the mobile phases were critical parameters in obtaining good retention and peak shapes of many of the above-mentioned polar and acidic metabolites that are impossible to analyze using standard reversed-phase LC/MS. Optimum conditions were found when using a gradient from 5 mM hexylamine in water (pH 6.