PT - JOURNAL ARTICLE AU - Ole Kristian Brandtzaeg AU - Elin Johnsen AU - Hanne Roberg-Larsen AU - Knut Fredrik Seip AU - Siri Leknes AU - Elsa Lundanes AU - Steven Ray Wilson TI - Preprint: A robust peptidomics mass spectrometry platform for measuring oxytocin in plasma and serum AID - 10.1101/042416 DP - 2016 Jan 01 TA - bioRxiv PG - 042416 4099 - http://biorxiv.org/content/early/2016/03/04/042416.short 4100 - http://biorxiv.org/content/early/2016/03/04/042416.full AB - Current approaches to measuring the cyclic peptide oxytocin in plasma/serum are associated with poor selectivity and/or inadequate sensitivity. We here describe a high performance nano liquid chromatography-mass spectrometry platform for measuring OT in human plasma/serum. The platform is extremely robust, allowing laborious sample clean-up steps to be omitted. OT binds strongly to plasma proteins, but a reduction/alkylation procedure breaks this bond, allowing ample detection of total OT. The method showed excellent quantitation properties, and was used to determine total OT levels to 0.5-1.2 ng/mL (evaluated with human plasma and cord serum). The method is compatible with accessible mass spectrometry instrumentation, finally allowing selective and easily comparable oxytocin measurements.