ANALYTICA CHIMICA ACTA ELSEVIER Analytica Chimica Acta 340 (1997) 169-174 Flow injection analysis of copper diethyldithiocarbamate in high resistance toluene media using a microelectrode detector T.J. Cardwell”,*, J.H. Santosa, A.M. Bondb ” Centre zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA for Scientific Instrumentation, School of Chemistry, Lu Trobe Univer.sity, Bundoora, Vie b Department of Chemistry Monash University, Clayton. Vi<-. 3168. Australia Received 18 June 1996; revised 23 October 1996; accepted 14 November 1996 3083, Australiil zyxwvutsrqponmlkj Abstract Flow injection (FI) analysis of copper as the copper diethylthiocarbamate complex (Cu(Et,dtc),) has been performed in a high resistance toluene carrier stream. The method is based on the oxidation of the copper complex at a platinum microelectrode fabricated to fit a Metrohm wall-jet flow cell. Electrodes of sizes 5 to 25 pm radii were tested in toluene-based carriers containing either 0.03 M tetrahexylammonium perchlorate (Hex,NClO,) or 35% acetonitrile. Detection limits (3 : I signal to noise ratio) in the range 1 x lo-’ M (5 pm radius electrode) to 5 x IO-* M (25 pm radius electrode) were achieved, which are comparable to detection limits reported in lower resistance media under similar conditions. The system was applied to the analysis of copper in water samples after extraction of the metal as its diethyldithiocarbamate into toluene and good agreement was found with data obtained by other voltammetric methods. Kewords: Flow injection; Microelectrodes; Toluene media; Copper 1. Introduction In 1982, Caudill et al. [l] reported microelectrode detection in flow injection (FI) analysis and high- performance liquid chromatography (HPLC) using an array of 5 pm radius carbon fibre microdisks in a thin-layer cell configuration which was insensitive to variations in flow rate. Later, the same group exploited the fast RC time response of their microelectrode array to apply rapid scanning and pulse voltammetric techniques to HPLC detection [2]. More recently, microelectrode detection systems *Corresponding author. Tel:+61 3 9479 2536; fax: +61 3 9479 1399: e-mail: T.Cardwell@latrobe.edu.au. capable of performing square wave, differential or normal pulse and cyclic voltammetry in flowing solutions have been developed for use in Fl or HPLC [3-71. Because of its sensitivity, simplicity of construc- tion and ease of use, the wall-jet flow cell is one of the most popular flow cells in amperometric detectors designed for use in HPLC or FI. Microelectrode working electrodes incorporated in home-made flow cells are common ([3] and references therein) but few reports have demonstrated their use in commercial wall-jet flow cells [8-l I]. This paper describes an amperometric detector in which a commercial wall-jet flow cell is modified by incorporation of a home-made platinum microelec- 0003-2670/97/$17.00 Copyright F> 1997 Elsevier Science B.V. All rights reserved PII SOOO3-2670(96)00546-6