Abstract
The atomization of lead in an electrothermal tungsten coil atomizer in the presence and absence of Na+, K+, Ca2+ and Mg2+ was investigated with the objective of understanding the interference processes. The lead atomization was less affected by Ca2+ and Mg2+ than by Na+ and K+. In the absence of concomitants, lead atomization efficiency was improved by the presence of H2 (10% v/v) in the purge gas composition, during pyrolysis and atomization steps. The interference caused by Na+ and Ca2+ was negligible when the pyrolysis step was accomplished without H2 in the purge gas composition. The results showed that Na+, K+, Ca2+ and Mg2+ are directly involved in competition reactions for H2 in condensed phase.
Highlights
In the last 25 years, loops, tubes, micro-tubes and coils made of tungsten or tungsten alloys have been proposed as atomizers for the determination of many elements by electrothermal atomic absorption spectrometry[1,2]
Newton and Davis[9] studied the effects of 27 cations and anions on lead atomization in a tungsten-rhenium loop atomizer and proposed that most of the interference was dependent on the heating rate of this atomizer
It was shown that 20% (v/v) of H2 in purge gas composition decreased the chemical interference and non-specific absorption due to concomitants
Summary
In the last 25 years, loops, tubes, micro-tubes and coils made of tungsten or tungsten alloys have been proposed as atomizers for the determination of many elements by electrothermal atomic absorption spectrometry[1,2]. Experiments carried out by Cantle andWest[8] showed that lead was less affected by interference when it was atomized from a tungsten filament than from a graphite filament of similar dimensions. Newton and Davis[9] studied the effects of 27 cations and anions on lead atomization in a tungsten-rhenium loop atomizer and proposed that most of the interference was dependent on the heating rate of this atomizer. The aim of the present work is to investigate the interference processes involved in lead atomization from the tungsten coil in the presence of Na+, K+, Ca2+ and Mg2+. The power supply was interfaced with the DS-15 Data Station, thereby enabling the tungsten coil furnace operation to be started by pushing the start GTA command. Argon 99.999 % (v/v) or a mixture containing 90% (v/v) Ar plus 10% (v/v) H2 (AGA, Campinas, Brazil) flowing at 1.0 L min-1 were used as purge gas
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