The assay of the catecholamine content of small volumes of human plasma

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Abstract
Plasma catecholamines are routinely measured using high‐performance liquid chromatography (HPLC) with electrochemical detection. Most of the present assays require sample volumes of at least 500 μL and are complex and labour‐intensive procedures, or require large capital investment to reduce the sample size. This paper describes a liquid/liquid plasma catecholamine extraction procedure, HPLC separation and electrochemical detection method which is simple, sensitive and reproducible. The resting catecholamine concentration of 50 μL adult human plasma can be assayed using standard electrochemical detection. The limits of detection were 0.1 fmol injected onto the column for each catecholamine. This method allows the routine assay of plasma catecholamine concentrations within the normal adult ranges in both 500 and 50 μL samples. The within assay coefficient of variation (CV) for noradrenaline (NA) was 1.2% in 500 μL plasma and 1.9% for 50 μL plasma, corresponding values for adrenaline (A) were 8.5 and 6.6%. The between assay CVs were 3.9 and 7.8% for NA, and 9.9 and 5.7% for A. Copyright © 1999 John Wiley & Sons, Ltd. Abbreviations used: A adrenaline bitartrate NA noradrenaline bitartrate PHBA 3,4‐ dihydroxy benzylamine hydrochloride DPBEA diphenylboric acid ethanolamine complex ToABr Tetraoctylammonium bromide ODS octadecylsilane