title: An untargeted gas chromatography mass spectrometry metabolomics platform for marine polychaetes.
abstract: The development of an appropriate extraction method for untargeted environmental metabolomic analysis of marine polychaetes could promote their use for environmental monitoring purposes. To this end, we compared four extraction methods on the marine polychaete Nereis virens both exposed to crude oil and non-exposed. XCMS was used for feature detection and preprocessing; different normalization and scaling approaches were tested; and principal component analysis (PCA) was used together with basic statistical tests to ascertain common metabolic patterns and determine the most suitable extraction method. We conclude that a two-step extraction procedure with 80:20 (v/v) methanol:water on freeze dried polychaete tissue provides the best trade-off between analysis time, and extraction efficiency and intermediate reproducibility. No definitive conclusions could be drawn about the ability of the method to discriminate controls and crude oils in actual biological replicates because the experiment was carried out by design on analytical replicates only. We show that the normalization to the sum of all the common features, and the use of a weighted least squares criterion to fit the PCA by means of scaling to the median absolute deviation (MAD) of the pooled quality control samples significantly improved the clustering of controls and crude oil exposed samples. The scaling alone led to an increase of 19% in explained variance compared to ordinary PCA.
authors: Department of Plant and Environmental Sciences, Faculty of Science, University of Copenhagen, Thorvaldsensvej 40, 1871 Frederiksberg C, Denmark; Assays Department, Chr Hansen A/S, Boege Alle 10, DK-2970 Hoersholm, Denmark. Electronic address: dkrafe@chr-hansen.com.
authors: R
authors: R
authors: Fernández-Varela
authors: Department of Plant and Environmental Sciences, Faculty of Science, University of Copenhagen, Thorvaldsensvej 40, 1871 Frederiksberg C, Denmark.
authors: G
authors: G
authors: Tomasi
authors: Department of Plant and Environmental Sciences, Faculty of Science, University of Copenhagen, Thorvaldsensvej 40, 1871 Frederiksberg C, Denmark.
authors: J H
authors: JH
authors: Christensen
mesh_terms: D000818:Animals; D004784:Environmental Monitoring / Q000379:methods*; D008401:Gas Chromatography-Mass Spectrometry / Q000592:standards*; D016018:Least-Squares Analysis; D055432:Metabolomics / Q000295:instrumentation*; D010578:Petroleum / Q000032:analysis; D011077:Polychaeta / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D025341:Principal Component Analysis; D015203:Reproducibility of Results; D014867:Water / Q000737:chemistry
chemical_list: D010578:Petroleum; D014867:Water
keywords: Derivatization; Environmental metabolomics; GC–MS; Marine polychaetes; Nereis virens; XCMS