Comparison of external calibration and isotope dilution LC-ICP-MS/MS for quantitation of oxytocin and its selenium analogue in human plasma

Research output: Contribution to journalJournal articleResearchpeer-review


  • Fulltext

    Submitted manuscript, 411 KB, PDF document

In the present study, a method for quantitation of the pharmaceutical peptide oxytocin (OT) and its diselenide-containing analogue (SeOT) in human plasma was developed using gradient elution LC-ICP-MS/MS. Plasma samples were precipitated with acetonitrile containing 1.0% TFA in a volume ratio of 1+3 (sample+precipitation agent) before analysis. Post-column isotope dilution analysis (IDA) was applied for quantitation and was compared with external calibration. Both calibration methods appeared to be fit for purpose regarding figures of merit including linearity, precision, LOD, LOQ and recovery. Analysis of OT and SeOT showed that selenium-based analysis is considerably more sensitive and selective compared to the sulfur-based analysis. Despite the relatively simpler setup of external calibration, IDA can be advantageous because it compensates for instrument drift and changes in organic solvent concentration. The method was applied for a stability study showing the degradation of OT and SeOT in plasma. The degradation of SeOT was faster than the degradation of OT in plasma. Thus, possible stability effects should be considered before replacing a disulfide bridge with a diselenide bridge or introducing a diselenide label in a potential drug. Graphical abstract: [Figure not available: see fulltext.]

Original languageEnglish
JournalAnalytical and Bioanalytical Chemistry
Pages (from-to)6479–6488
Publication statusPublished - 2021

Bibliographical note

Publisher Copyright:
© 2021, Springer-Verlag GmbH Germany, part of Springer Nature.

    Research areas

  • Inductively coupled mass spectrometry, Isotope dilution analysis, Liquid chromatography, Peptide quantitation, Se labelling

Number of downloads are based on statistics from Google Scholar and

No data available

ID: 282193169