Automated analysis for plasma epinephrine and norepinephrine by liquid chromatography, including a sample cleanup procedure.

We describe a fully automated method of analysis for plasma epinephrine and norepinephrine by use of a two-column system of "high-performance" liquid chromatography. Catecholamines in deproteinized plasma are purified on the first (preparation) column, then transferred automatically to the second (analytical) column in which epinephrine and norepinephrine are resolved. These compounds are then determined fluorometrically with a continuous-flow reaction system by the trihydroxyindole method. The minimum sensitivity of the method is 0.02 and 0.04 pmol for epinephrine and norepinephrine, respectively. One assay can be completed in 30 min, and greater than 1 mL of plasma is required for the procedure. The within-run CV in the chromatographic determination of pooled plasma was greater than 3%, and the analytical overall recovery of the two compounds was 95%. The concentrations in plasma of medical students at rest were 0.32 (SE 0.06) nmol/L for epinephrine and 0.98 (SE 0.08) nmol/L for norepinephrine.