The neuropeptide oxytocin is well known for its role during childbirth and lactation as well as its positive behavioural effects such as increase in empathy and its involvement in pair bonding. Oxytocin`s multi‑functionality is currently investigated to treat a variety of different diseases such as breast and prostate cancer as well as neurological diseases e.g. autism spectrum disorder or schizophrenia. However, it remains unclear how oxytocin levels in blood or cerebrospinal fluid correlate to different diseases and if oxytocin can be used as a biomarker or treatment option. This gap of knowledge is due to very low endogenous oxytocin levels in humans (low pg/mL) that make the analysis extremely difficult. In addition, current assays involve hazardous radioactive material (radio immune assay), lack of specificity and/or sensitivity (enzyme linked immune assay) or have poor reproducibility and/or experimental procedure.

Here we describe the development of a simple and efficient approach to measure oxytocin via mass spectrometry, using proteomic techniques. We labelled different functional groups within the peptide to improve ionisation and fragmentation of oxytocin within the mass spectrometer and optimised sample preparation.