Used in biomedical research to measure vasopressin levels in biological samples such as plasma, serum, or cerebrospinal fluid. Widely applied in studies related to fluid balance, stress response, and disorders like diabetes insipidus, syndrome of inappropriate antidiuretic hormone secretion (SIADH), and heart failure. Enables quantitative analysis in clinical and preclinical settings, supporting endocrine and neurological research. Also utilized in pharmacological studies assessing drug effects on the hypothalamic-pituitary axis.