Improving the extraction efficiency of sedimentary carbohydrates by sequential hydrolysis

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  • Rong Zhu, Swiss Federal Institute of Technology Zurich
  • ,
  • Julie Tolu, Swiss Federal Institute of Technology Zurich, Swiss Federal Institute of Aquatic Science and Technology
  • ,
  • Longhui Deng, Swiss Federal Institute of Technology Zurich
  • ,
  • Annika Fiskal, Swiss Federal Institute of Technology Zurich
  • ,
  • Lenny H.E. Winkel, Swiss Federal Institute of Technology Zurich, Swiss Federal Institute of Aquatic Science and Technology
  • ,
  • Mark A. Lever

Carbohydrates serve as structural materials, energy storage compounds, and energy carriers in organisms and provide insights into the dominant sources and the degradation state of organic matter (OM). Several studies have analyzed dissolved and/or particulate carbohydrates in the environment, often with the aim of studying particular carbohydrate groups of interest. These studies have often employed different acids and hydrolytic conditions, making comparisons across studies a challenge. Here, we introduce a sequential acid hydrolysis protocol for the comprehensive extraction, quantification and compositional investigation of carbohydrates in sediment samples. This protocol has four acid hydrolysis steps that sequentially increase in extraction strength, where each subsequent hydrolysis step is performed on the unextracted remains previously hydrolyzed. The four hydrolysis steps consist of 1 M HCl for 2 h at (1) room temperature, (2) 50 °C, and (3) 105 °C, followed by incubation for 8 h using (4) 6 M HCl and 105 °C. Based on tests using diverse carbohydrate standard compounds, the protocol recovers most di- and oligosaccharides and soluble polysaccharides during the initial hydrolysis steps, whereas the recovery of most insoluble polysaccharides is highest during the final extraction step. Applying this protocol to different sediment types shows that recoveries of neutral sugars, amino sugars and sugar alcohols are on average ~60% higher than with a reference one-step extraction method using only hydrolysis with hot 6 M HCl. This sequential extraction protocol thus provides an important new tool for the quantitative and compositional analysis of carbohydrates in aquatic sediments.

Original languageEnglish
Article number103963
JournalOrganic Geochemistry
Volume141
ISSN0146-6380
DOIs
Publication statusPublished - Mar 2020
Externally publishedYes

Bibliographical note

Funding Information:
Samples were retrieved from field trips to Aarhus Bay (Denmark), Lake Lucerne (Switzerland), Lake Greifen (Switzerland), and during RV Meteor cruise SO241 to Guaymas Basin (Gulf of California). All Py-GC/MS measurements were performed at the Department of Ecology and Environmental Science, Umeå University, Sweden. We thank all participating scientists and ship crews for sample recovery, Kristopher McNeill and Sam Zeeman for instrument support, Junko Takahashi-Schmidt for the Py-GC/MS analysis, as well as Madalina Jaggi and Barbara Pfister for technical assistance. This study was supported by the Swiss National Science Foundation (project no. 200021_169366) to M. A. Lever, and by departmental funds to M. A. Lever and L. H. E. Winkel from ETH Zurich.

Publisher Copyright:
© 2020 Elsevier Ltd

Copyright:
Copyright 2020 Elsevier B.V., All rights reserved.

    Research areas

  • Carbohydrate, Extraction efficiency, GC-FID, Improved recovery, Lacustrine sediment, Marine sediment, Organic carbon pool, Py-GC/MS, Sequential hydrolysis

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