Development and validation of a highly sensitive LC–MS/MS assay for the quantification of arginine vasopressin in human plasma and urine: Application in preterm neonates and child

• UPLC–MS/MS is highly sensitive for the quantification of arginine vasopressin.
• AVP levels determined by UPLC–MS/MS are consistent with the published data.
• The developed method is ready to be used in clinical studies of AVP.

Arginine vasopressin is an endogenous neuropeptide secreted in response to situations such as hyperosmolality, hypotension and hypovolemia. The purpose of this study was to develop a reliable assay using small volumes of plasma and urine samples to quantify vasopressin levels in preterm infants. Weak cation solid-phase extraction was used to extract vasopressin from 200 μl human plasma and urine samples. Separation was achieved on a Waters Acquity UPLC BEH C18 column by gradient elution at 0.55 ml/min, with a mobile phase composed of methanol and 0.02% aqueous acetic acid solution. Analysis was performed under a hybrid triple quadrupole linear ion trap mass spectrometer, operated in multiple reaction monitoring mode using positive ionization. The linear response range was 1.0–40 pg/ml for vasopressin, with the lower limit of quantification (LLOQ) of 1.0 pg/ml in human plasma and urine. Recoveries at concentrations of 3, 10 and 32 pg/ml were all greater than 70%, and matrix effects were within 15%. The method was validated with intra-day and inter-day precision of less than 8% for human plasma and urine. The intra-day and inter-day accuracy for human plasma were 91.9–100.6% and 92.3–104.8%, respectively. The intra-day and inter-day accuracy for human urine were 89.2–95.9% and 89.3–91.3%, respectively. The validated method was successfully applied to analyze two preterm neonate plasma samples and one child urine sample. In conclusion, the developed and validated method was sensitive and reliable, and was successfully used to quantify endogenous vasopressin levels in neonate plasma and child urine.

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