title: The effect of freeze/thaw cycles on reproducibility of metabolic profiling of marine microalgal extracts using direct infusion high-resolution mass spectrometry (HR-MS).
abstract: During normal sample preparation, storage in freezers and subsequent freeze/thaw cycles are commonly introduced. The effect of freeze/thaw cycles on the metabolic profiling of microalgal extracts using HR-MS was investigated. Methanolic extracts of monocultures of Arctic marine diatoms were analyzed immediately after extraction, after seven days of storage at -78 °C (one freeze/thaw cycle), and after additional seven days at -20 °C (two freeze/thaw cycles). Repeated direct infusion high-resolution mass spectrometry analysis of microalgae extracts of the same sample showed that reproducibility was ca. 90% when a fresh (unfrozen) sample was analyzed. The overall reproducibility decreased further by ca. 10% after the first freeze/thaw-cycle, and after one more freeze/thaw cycle the reproducibility decreased further by ca. 7%. The decrease in reproducibility after freeze-thaw cycles could be attributed to sample degradation and not to instrument variability.
authors.affiliation: Department of Arctic and Marine Biology, Faculty of Biosciences, Fisheries and Economics, UiT The Arctic University of Norway, Tromsø N-9037, Norway. hans.c.eilertsen@uit.no.
authors.forename: Hans Chr
authors.initials: HC
authors.lastname: Eilertsen
authors.affiliation: MabCent-SFI, UiT The Arctic University of Norway, Tromsø N-9037, Norway. siv.huseby@uit.no.
authors.forename: Siv
authors.initials: S
authors.lastname: Huseby
authors.affiliation: Department of Arctic and Marine Biology, Faculty of Biosciences, Fisheries and Economics, UiT The Arctic University of Norway, Tromsø N-9037, Norway. maria.degerlund@uit.no.
authors.forename: Maria
authors.initials: M
authors.lastname: Degerlund
authors.affiliation: Department of Arctic and Marine Biology, Faculty of Biosciences, Fisheries and Economics, UiT The Arctic University of Norway, Tromsø N-9037, Norway. gunilla.eriksen@uit.no.
authors.forename: Gunilla K
authors.initials: GK
authors.lastname: Eriksen
authors.affiliation: Department of Arctic and Marine Biology, Faculty of Biosciences, Fisheries and Economics, UiT The Arctic University of Norway, Tromsø N-9037, Norway. richard.a.ingebrigtsen@uit.no.
authors.forename: Richard A
authors.initials: RA
authors.lastname: Ingebrigtsen
authors.affiliation: Marbio, UiT The Arctic University of Norway, Tromsø N-9037, Norway. espen.hansen@uit.no.
authors.forename: Espen
authors.initials: E
authors.lastname: Hansen
mesh_terms: D000064:Acclimatization; D017377:Diatoms / Q000502:physiology*; D013058:Mass Spectrometry / Q000379:methods*; D055432:Metabolomics / Q000379:methods*; D000432:Methanol / Q000378:metabolism; D058086:Microalgae / Q000502:physiology; D015203:Reproducibility of Results
chemical_list: D000432:Methanol