In this work, a new chelating resin [1,5-bis (2-pyridyl)-3-sulphophenyl methylene] thiocarbonohydrazide immobilised on aminopropyl-controlled pore glass (550 Å; PSTH-cpg) was synthesised and packed in a microcolumn which replaced the sample tip of the autosampler arm. The system was applied to the preconcentration of lead. When microliters of 10% HNO3, which acts as elution agent, pass through the microcolumn, the preconcentrated Pb(II) is eluted and directly deposited in a tungsten-rhodium coated graphite tube. With the use of the separation and preconcentration step and the permanent modifiers, the analytical characteristics of the technique were improved. The proposed method has a linear calibration range from 0.012 to 10 ng ml−1 of lead. At a sample frequency of 36 h−1 with a 90 s preconcentration time, the enrichment factor was 20.5, the detection and determination limits were 0.012 and 0.14 ng ml−1, respectively and the precision, expressed as relative standard deviation, was 3.2% (at 1 ng ml−1). Results from the determination of Pb in biological certified reference materials were in agreement with the certified values. Seawaters and other biological samples were analysed too.
Electrothermal atomic absorption spectrometry On-line preconcentration Lead Permanent chemical modified Seawaters Biological samples
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The authors thank the Spanish Ministerio de Ciencia y Tecnología (MCYT) for supporting this study, project BQU2003-02112 and also the Junta de Andalucía.