The Effect of Freeze/Thaw Cycles on Reproducibility of Metabolic Profiling of Marine Microalgal Extracts Using Direct Infusion High-Resolution Mass Spectrometry (HR-MS)

• Published in: Molecules
• Main Authors: Eilertsen, Hans Chr., Huseby, Siv, Degerlund, Maria, Eriksen, Gunilla K., Ingebrigtsen, Richard A., Hansen, Espen
• Format: Text
• Language: English
• Published: MDPI 2014
• Subjects: Communication; Arctic
• Online Access: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6271507/; http://www.ncbi.nlm.nih.gov/pubmed/25314600; https://doi.org/10.3390/molecules191016373

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.