ELSEVIER Analytica Chimica Acta 31.5 (199.5) 69-76 ANALmcA CHIMICA ACTA Determination of copper in human plasma by stripping potentiometry on a mercury film electrode in ethylenediamine medium Eduardo Pinilla Gil, Rosa Ma Garcia-Monc6 Carra, Antonio SBnchez Misiego * Departamento de Q&mica Analitica y Electroquimica, hive&dad de Extremadura, 06071 Baahjoz, Spain Received 2 January 1995; revised 1.5 May 1995; accepted 21 May 1995 zyxwvutsrqponmlkjihgfedcbaZYXW Abstract The use of ethylenediamine improves the determination of copper by potentiometric stripping analysis on a mercury film electrode, with respect to the usual determination method in acidic medium. The influence of chemical and methodological parameters is discussed, and the reliability of the method is checked with certified reference materials. Influence of the acid digestion protocol in open and high pressure closed vessels is investigated. The method developed has been applied to the measurement of the copper level in mineralized human plasma samples. The results have been compared with those obtained by electrothermal atomic absorption spectroscopy in a graphite furnace. Keywords: Potentiometry; Copper; Plasma 1. Introduction Copper is one of the most widespread distributed elements in the enviromnent of industrialized coun- tries. As a bioessential element, copper participates in many biochemical processes. It is known that a deviation of copper level from normal values in the human body causes serious effects on health. Nega- tive consequences of excess or lack of copper, that may even result on death, are extensively docu- mented [l-51. It has also been demonstrated that cancer produces a marked alteration of copper * Corresponding author. metabolism and distribution in the body [3,6-lo], although the specific relation between tumoral activ- ity and copper levels is not yet fully understood. Copper is usually determined in clinical laborato- ries by use of atomic absorption spectrometry (AAS) [ll], and the same technique has been employed to determine copper reference values in normal popula- tions [12]. Recently, Vandecasteele et al. [13] and Vanhoe et al. 1141 have published data for copper and other trace elements in biological samples using inductively coupled plasma combined with mass spectrometry. Electroanalytical techniques have often been used for copper determination. Ion selective electrodes have been developed to measure copper in toxicolog- ical studies and in the monitoring of the aquatic 0003-2670/95/$09.50 0 1995 Elsevier Science B.V. All rights reserved SSDIOOO3-2670(95)00288-X