Development of a liquid chromatography coupled to tandem mass spectrometry method for the quantification of Arginine Vasopressin in human plasma.

Arginine Vasopressin (AVP) is a nonapeptide synthesized in the hypothalamus and released by the neurohypophysis. It plays a central role in water and electrolyte homeostasis, urine concentration and blood pressure regulation. Dysregulation of AVP secretion is associated with several pathological conditions, including central diabetes insipidus and syndrome of inappropriate antidiuretic hormone secretion. Currently, AVP quantification mainly relies on immunoassays which suffers from limitations such as cross reactivity, limited sensitivity and complex sample handling. Given the very low endogenous concentrations of AVP in human plasma (low ng/L range), a highly sensitive LC-MS/MS method was developed and validated for plasma AVP quantification. AVP was extracted using Oasis WCX solid-phase extraction prior to LC-MS/MS analysis. PBS containing 0.1% BSA was used as surrogate matrix for calibration and validation samples to avoid endogenous interferences. Method validation was performed according to the Clinical Laboratory Standards Institute guidelines. Precision, accuracy, and measurement uncertainty were evaluated using single-nested analysis of variation and e.noval software. Stability in whole blood and plasma samples was also investigated. The method was validated over a concentration range from 0.2 ng/L to 60 ng/L, with precision (coefficient of variation) below 10%, accuracy ranging from 96% and 109%, measurement uncertainty below 15%, and a lower limit of quantification of 0.2 ng/L. EDTA blood samples remained stable up to 3 h at room temperature before centrifugation. In conclusion, we have developed and validated a highly sensitive LC-MS/MS method for the quantification of AVP in plasma. Our novel methodology is well-suited for clinical applications.