Analytical evaluation of a tungsten coil atomizer for cadmium, lead, chromium, manganese, nickel and cobalt determination by electrothermal atomic absorption spectrometry

Abstract

The analytical performance of an unenclosed tungsten coil atomizer operating in Ar-H 2 (90:10) was assessed by electrothermal atomic absorption spectrometry (ETAAS) for the determination of pg to ng levels of Cd, Co, Cr, Mn, Ni and Pb in liquid samples. A three-steps low power unit provided the heating programme for the tungsten coil with dry, pyrolysis and vaporization-atomization as sequential steps, and shortlived absorption signals (100–250 ms) were produced with an analysis time of 100 s. Parameters studied were the current applied to the coil; temperatures and duration of the three heating steps; purge gas flow rate; coil alignment in the radiation beam; and sample volume. Under optimized conditions, linear working ranges extended between 0–2.0 μg l −1 for Cd and 0–100 μg l −1 for Ni and Pb, and characteristic masses were between 0.3 pg (Cd) and 14 pg (Pb). Within-day reproducibility (relative standard deviation) of measurements varied between 2.2% (Cr) and 7.5% (Pb), and between-day was < 8% (Pb) in the analyte's linear working ranges, being acceptable for manual sample introduction used in this atomizer. Detection limits (3σ B1 ) were in the range 0.6 pg (Cd)-23 pg (Pb).