Incorporating standardised drift-tube ion mobility to enhance non-targeted assessment of the wine metabolome (LC×IM-MS)

Liquid chromatography with drift-tube ion mobility spectrometry-mass spectrometry (LCxIM-MS) is emerging as a powerful addition to existing LC-MS workflows for addressing a diverse range of metabolomics-related questions [1,2]. Importantly, excellent precision under repeatability and reproducibility conditions of drift-tube IM separations [3] supports the development of non-targeted approaches for complex metabolome assessment such as wine characterisation [4]. In this work, fundamentals of this new analytical metabolomics approach are introduced and application to the analysis of 90 authentic red and white wine samples originating from Macedonia is presented. Following measurements, intersample alignment of metabolites using non-targeted extraction and three-dimensional alignment of molecular features (retention time, collision cross section, and high-resolution mass spectra) provides confidence for metabolite identity confirmation. Applying a fingerprinting metabolomics workflow allows statistical assessment of the influence of geographic region, variety, and age. This approach is a state-of-the-art tool to assess wine chemodiversity and is particularly beneficial for the discovery of wine biomarkers and establishing product authenticity based on development of fingerprint libraries

Hidden methanol assimilation pathways in the methylotrophic yeast Pichia pastoris

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Recommendations for reporting ion mobility mass spectrometry measurements

© 2019 The Authors. Mass Spectrometry Reviews Published by Wiley Periodicals, Inc. Here we present a guide to ion mobility mass spectrometry experiments, which covers both linear and nonlinear methods: what is measured, how the measurements are done, and how to report the results, including the uncertainties of mobility and collision cross section values. The guide aims to clarify some possibly confusing concepts, and the reporting recommendations should help researchers, authors and reviewers to contribute comprehensive reports, so that the ion mobility data can be reused more confidently. Starting from the concept of the definition of the measurand, we emphasize that (i) mobility values (K0) depend intrinsically on ion structure, the nature of the bath gas, temperature, and E/N; (ii) ion mobility does not measure molecular surfaces directly, but collision cross section (CCS) values are derived from mobility values using a physical model; (iii) methods relying on calibration are empirical (and thus may provide method-dependent results) only if the gas nature, temperature or E/N cannot match those of the primary method. Our analysis highlights the urgency of a community effort toward establishing primary standards and reference materials for ion mobility, and provides recommendations to do so. © 2019 The Authors. Mass Spectrometry Reviews Published by Wiley Periodicals, Inc

Incorporating standardised drift-tube ion mobility to enhance non-targeted assessment of the wine metabolome (LC×IM-MS)

Liquid chromatography with drift-tube ion mobility spectrometry-mass spectrometry (LCxIM-MS) is emerging as a powerful addition to existing LC-MS workflows for addressing a diverse range of metabolomics-related questions [1,2]. Importantly, excellent precision under repeatability and reproducibility conditions of drift-tube IM separations [3] supports the development of non-targeted approaches for complex metabolome assessment such as wine characterisation [4]. In this work, fundamentals of this new analytical metabolomics approach are introduced and application to the analysis of 90 authentic red and white wine samples originating from Macedonia is presented. Following measurements, intersample alignment of metabolites using non-targeted extraction and three-dimensional alignment of molecular features (retention time, collision cross section, and high-resolution mass spectra) provides confidence for metabolite identity confirmation. Applying a fingerprinting metabolomics workflow allows statistical assessment of the influence of geographic region, variety, and age. This approach is a state-of-the-art tool to assess wine chemodiversity and is particularly beneficial for the discovery of wine biomarkers and establishing product authenticity based on development of fingerprint libraries

Using sheath-liquid reagents for capillary electrophoresis-mass spectrometry: Application to the analysis of phenolic plant extracts

The combination of CE and MS is now a widely used tool that can provide a combination of high resolution separations with detailed structural information. Recently, we highlighted the benefits of an approach to add further functionality to this well-established hyphenated technique, namely the possibility to perform chemical reactions within the sheath-liquid of the CE-MS interface . Apart from using hydrogen/deuterium exchange for online determination of numbers of exchangeable protons, the addition of DPPH• (2,2-diphenyl-1-picrylhydrazyl) to the sheath-liquid can be used as a fast screening tool for studying antioxidant characteristics of individual components. Such a CE-MS methodology allows rapid and information-rich analysis with minimal reagent and sample consumption to be performed. In the present work, we demonstrate the applicability of this approach for the characterization of phenolic plant extracts from the Labiatae family, namely Rosmarinus officinalis and Melissa officinalis. Using the described approach, a wide range of compounds (15 and 13 phenolic compounds, respectively) could be confidently identified using a combination of high resolution CE-MS separations with implementation of online deuterium exchange and DPPH• reactions. These compounds included polyphenols, phenolic acids, and triterpene acids. In conjunction with online MS/MS experiments, extensive structural information for aglyconic and glycosylated antioxidants present in the extracts could be obtained using simple experimental changes, which can be carried out prior to the purchasing of expensive chemical standards or the time-consuming preparative isolation of individual compounds.T.J.C. is the recipient of a Lise Meitner Fellowship (M1572-N19) from the Austrian Science Funds (FWF).Peer Reviewe

Fingerprinting of traditionally produced red wines using liquid chromatography combined with drift tube ion mobility-mass spectrometry

The characterization of wine via MS-based metabolic fingerprinting techniques remains a challenging undertaking due to the large number of phenolic compounds that cannot be confidently annotated and identified within analytical workflows. The combination of high performance liquid chromatography with low-field drift tube ion mobility time-of-flight mass spectrometry (HPLC x IMS-TOFMS) offers potential for the confident characterization and fingerprinting of wine using a metabolomics-type workflow. In particular, the use of collision cross section values from low-field drift tube IMS using nitrogen as drift gas ((CCSN2)-C-DT) in addition to retention time and a high resolution mass spectrum for putative compounds allows rugged statistical assessment and identity confirmation using CCS libraries (<0.5% error) to be performed. In the present work, an HPLC x IMS-TOFMS platform has been utilized for the fingerprinting of 42 traditionally produced red wines emanating from the Republic of Macedonia. After establishing the reliability of (CCSN2)-C-DT as an identification point for wine metabolomics in both ionization modes, fingerprinting of wines according to grape variety was undertaken and a full dataset containing retention, accurate mass and (CCSN2)-C-DT values used to derive lists of compounds found to be statistically characteristic for each variety. Putative compounds were further assessed by assignment of in-source and post-drift mass fragments aligned according to retention time, drift time, and accurate mass providing up to seven identification points for a single compound when data from both positive and negative mode measurements are combined

Classification of wine by determination of bioactive phenolic compounds using high resolution mass spectrometry

In this project proposal, metabolomic fingerprinting of wine samples will be examined using high performance liquid chromatography combined with ion mobility quadruple time-of-flight mass spectrometry (HPLC–IMS-QTOF-MS) for the first time. Bioactive compounds in wines from various red and white varieties produced in Macedonia and Austria from different wine regions and different vintages will be determined for the first time using a non-targeted fingerprinting approach on this analytical platform. An automated compound extraction algorithm will be employed for processing background-subtracted high-resolution MS data in order to correctly align compounds detected in analyzed samples. It is expected that a huge number of compounds will be determined that will enable powerful metabolomic fingerprinting of the studied wines and, therefore, provide a means to classify samples according to the geographic origin and grape variety as well as determination of wine authenticity. Data processing will be performed with sophisticated software that can process the high-resolution IMS-MS and MS/MS data from the measurements applying multivariate statistical analyses including principal component analysis (PCA), factor analysis (FA) and one-way ANOVA. Each chromatogram and IMS-MS spectrum will be regarded as an individual fingerprint of a wine sample, which includes information about grape variety, origin, vintage, physiological state, technological treatment, and other factors. These data will be used to create a database for the Macedonian wines, which will be the first database of its kind, as well as a database for the Austrian wines. Furthermore, characterization of the antioxidant properties of wines and wine bioactive phenols will be performed using electrochemical measurements with square-wave and cyclic voltammetry

Application of liquid chromatography combined with low-field drift tube ion mobility time-of-flight mass spectrometry (HPLC×IM-TOFMS) for red wine fingerprinting

Phenolic compounds are important quality components in red wine affecting the taste of bitterness and astringency, the color and long wine stability and aging. In this study, a rapid and sensitive analytical technique was used for detailed phenolics fingerprinting of 42 Macedonian red wines produced from different wine regions. Analyses were performed using high performance liquid chromatography in combination with low-field drift tube ion mobility time-of-flight mass spectrometry (HPLC×IMS-TOFMS). The reliability of DTCCSN2 values, based on consensus values from a standardized and reproducible workflow, was evaluated as an identification point for wine metabolomics. Using appropriate software tools for alignment and statistical evaluation, a full dataset for each wine was obtained, including retention time, accurate mass, fragment spectra and DTCCSN2. Putative compounds were further assessed by assignment of in-source and post-drift mass fragments aligned according to retention time, drift time, and accurate mass. Up to seven identification points for a single compound can be generated when data from both positive and negative mode measurements are combined. The correlation between abundance across the two ionization modes was found to be very good in many examples with correlation coefficients (R2) values of 0.63-0.97 for eleven putative metabolites in Vranec wines, and 0.70-0.99 for nine putative metabolites in Pinot Noir. Acknowledgments: The Ministry of Education and Science of the Republic of Macedonia and the Austrian Agency for International Cooperation in Education and Research (OeAD) are thanked for financial support (Bilateral Project between Austria and R. Macedonia, MK 12/2016). Vienna Business Agency and EQ BOKU VIBT GmbH are acknowledged for providing mass spectrometry instrumentation. Keywords: wine phenolics fingerprinting, HPLC×IMS-TOFMS

Molecular Weight and Tacticity of Oligoacrylates by Capillary Electrophoresis-Mass Spectrometry

International audienceOligo(acrylic acid) efficiently stabilizes polymeric particles, especially particles produced by reversible addition-fragmentation chain transfer (RAFT) (as hydrophilic block of an amphiphilic copolymer). Capillary electrophoresis (CE) has a far higher resolution power to separate these oligomers than the commonly used size exclusion chromatography. Coupling CE to electrospray ionization mass spectrometric detection unravels the separation mechanism. CE separates these oligomers, not only according to their degree of polymerization, but also according to their tacticity, in agreement with NMR analysis. Such analysis will provide insight into the role of these oligomers as stabilizers in emulsion polymerization, and into the mechanism of the RAFT polymerization with respect to degree of polymerization and tacticity