MEASUREMENT OF CONJUGATED CATECHOLAMINES IN HUMAN PLASMA - A LOW-COST HPLC-ECD METHOD

We present an HPLC assay with electrochemical detection of conjugated catecholamine levels in human plasma. This method allows the direct assessment of the conjugated catecholamine values without the subtraction of the free catecholamine amounts: the assay is performed in the residual supernatant after the extraction (and the assay) of free catecholamines. The results are comparable with the classic enzymatic and acid-heat hydrolysis methods (which yield the sum of free and conjugated catecholamine concentrations). This technique shows good reproducibility (within-run and between-run CVs < 8% in the physiological range), and sensitivity (< 20 pg per each deconjugated catecholamine per extract). This method allows about 30 low cost determinations of plasma free and conjugated catecholamines to be done in a working day.