Abstract

New materials have significant impact on development of new methods and instrumentation for chemical analysis. From the discovery of carbon nanotubes in 1991, single and multi-walled carbon nanotubes (SWCNTs and MWCNTs) -due to their high adsorption and desorption capacities- have been employed as sorption substrates in solid-phase extraction for the preconcentration of heavy metals from diverse matrices. In the present work, a new method for the Pb determination by electrothermal atomic absorption spectrometry (ETAAS) in urine at low levels has been developed. Lead was separated from the undesirable urine matrix by means of a solid phase extraction (SPE) procedure using oxidized multiwalled carbon nanotubes as a sorbent material.

Highlights

  • Lead is a toxic heavy metal that does not have any known positive physiological role in the human body

  • Different variables that influence the solid phase extraction (SPE) retention of lead ions by multiwalled carbon nanotubes (MWCNTs) packed in the microcolumn were initially studied evaluated by means of a screening study using a half-fraction factorial design [25–1] in 16 randomized experiments

  • A SPE procedure using MWCNTs as sorbent material has been developed for the extraction of Pb from human urine samples prior to electrothermal atomic absorption spectrometry (ETAAS) determination

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Summary

Introduction

Lead is a toxic heavy metal that does not have any known positive physiological role in the human body. Since the lead level in urine reflects the amount of the element that has been recently absorbed, the determination of Pb in urine is useful for assessing occupational and environmental exposure[1]. The determination of Pb in urine requires a pretreatment step as well as sensitive instrumental techniques such as ETAAS. In this case, SPE using oxidized MWCNTs was employed as preconcentration method. Since the discovery of carbon nanotubes (CNTs) in 1991 by Ijima[2], it became clear that they might be an excellent material for SPE because of their high surface area and inner volume, stability, mechanical strength and the possibility of establishing π-π interactions. CNTs are hollow graphitic material composed by one (named single-walled carbon nanotubes, SWCNT) or multiple (named multi-walled carbon nanotubes, MWCNT) layers of graphene sheets arranged (Figure 1)

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