| Concentrations of catecholamines (CA) in plasma reflect, to a significant extent, the activity level of the sympathetic nervous system but a sensitive means to accurately quantify the CA on a routine basis had not previously been readily available.;A number of unique features have been incorporated into this assay to achieve and maintain its sensitivity. These include a novel method of cleaning the HPLC-ECD apparatus on a daily basis with no attendant loss of sensitivity and with a minimal re-equilibration period (i.e., less than one-half hour). Additionally, a novel method of polishing the glassy carbon working electrode (WE) is described. This polishing technique restores the sensitivity of the WE to its original status (as determined when the WE is new). Recommendations are made regarding the details essential to the operation of the assay on a regular basis and to the continued preservation of the high level of sensitivity of the assay for routine use.;The performance of this CA assay was tested under the constraints of a clinical setting in an effort to judge the ability of the assay to perform under these conditions and in an attempt to answer a clinical question: are plasma CA concentrations elevated in patients who have suffered a subarachnoid hemorrhage due to rupture of a cerebral artery aneurysm? Based on the data collected in the present instance, no firm conclusions could be drawn about the contribution of plasma CA levels to the development of clinical complications in this group of patients.;The present work has involved the development of a reliable, sensitive and reproducible human plasma CA assay. An efficient boric acid extraction method was used to extract the CA from plasma; the CA were subsequently separated and detected by high pressure liquid chromatography (HPLC) and (amperometric) electrochemical detection (ECD), respectively. An on-line, dedicated integrator was used to obtain and record an objective assessment of the peak heights of the analytes on the chromatogram. The entire assay technique described herein has been optimized to accommodate the operation of the ECD at the high sensitivity level (namely, 1 nanoamp full scale deflection of the ECD response) required by the low levels of endogenous CA found in resting human plasma. |
