On-line coupling of electrochemical preconcentration in tungsten coil electrothermal atomic absorption spectrometry for determination of lead in natural waters

A flow injection system was coupled to a tungsten coil electrothermal atomi zer (150 W) for on-line separation and preconcentration of lead based on it s electrochemical reduction on the atomizer surface. The electrochemical ce ll is built up inside the furnace by using a Pt flow-through anode and the atomizer itself as the flow-through cathode. The manifold and the tungsten coil power supply were controlled by a computer running a program written i n Visual Basic, which was utilized in synchronism with the original softwar e of the atomic absorption spectrometer. The flow-through anode (50 mm long , 0.7 mm i.d.) was inserted in tip of the autosampler arm by replacing the last section of the PTFE sample delivering tube. The tungsten coil atomizer and the counter electrode were easily connected to a d.c. power supply. An enrichment factor of 25 was obtained for lead after a 120-s electrodeposit ion for a sample flowing at 1.0 ml min(-1). The method detection limit was 0.2 mu g l(-1) Pb and the R.S.D. < 5% (n = 10 for 5 mu g l(-1) Pb). Up to 2 % m/v NaCl or KCl and 5% m/v CaCl2 or MgCl2 did not interfere on the separa tion and atomization of 5 mu g l(-1) Pb. (C) 1999 Elsevier Science B.V. All rights reserved.