On-line Preconcentration and Determination of Lead in Iron and Steel by Flow Injection-Flame Atomic Absorption Spectrometry

Abstract

High purity iron has recently received much attention as a new material with excellent characteristics. 1,2 The development of reliable analytical methods for the determination of trace impurity elements are required for production of pure iron. On the other hand, the use of scrap iron is increasing to make use of resources effectively and the accurate determination of various impurity metals in iron and steel is therefore essential for the quality control of iron products.The detection limit of lead by flame atomic absorption spectrometry (FAAS) is about 10 ng/ml. 3 Therefore the determination of traces of lead in high purity metals by FAAS usually requires its preconcentration, in addition to the separation of lead from matrix elements. Generally the blank value introduced from the reagents or from the laboratory environment must be kept at as low a level as possible in order to obtain the precise analytical results for traces of lead.Flow injection (FI) on-line preconcentration procedures now play an important role in trace metal analysis. They offer the possibility of determining lower analyte concentrations and avoiding matrix effects by separation of the analyte from interfering matrix components. Furthermore the consumption of time, sample and reagent, and the risk of contamination from the laboratory environment are low; the repeatability and efficiency are high compared with its corresponding batch counterpart procedures. [4][5][6][7] In this respect, FI systems combined with ion exchange or solid phase extraction techniques carried out in minicolumns have been successfully used in flame atomic absorption spectrometry (FAAS) because the preconcentrated analytes can be simply eluted into the nebulizer. [5][6][7][8] A large variety of highly efficient sorbents are usually used in on-line techniques for determination of trace metals, as reviewed by Yebra-Biurrum. 9 These sorbents include inorganic activated alumina; ion exchangers modified with complexing reagents; sorbents based on silica gel, naphthalene, styrenedivinylbenzene copolymers (XAD), and porous glass beads with immobilized chelates groups; reversed-phase silica sorbent (C18, C16 and C8); activated carbon; and chelating resins and celluloses. The typical chelating resin, Chelex-100, with iminodiacetate chelating groups has been among the most used. These sorbents are mostly used for determination of trace metal ions in natural water, biological samples, and food, but in some cases, these samples bring about difficulties if they contain large amounts of metal ions. For example, this problem gets complicated when trace elements are determined in complex metallic matrix samples such as waste water, alloys and rocks, because the column adsorbs not only micro components but also some matrix elements like iron, copper and others as well, and the sorbent capacity is insufficient.This work was undertaken to examine a Pb-selective chromatographic resin, 10 Pb·Spec TM (EIChrom Industries), to preconcentrate and separate lead from other sample matrix comp...

Determination of Lead in Seawater by Flow-Injection On-line Preconcentration–Electrothermal Atomic Absorption Spectrometry after Coprecipitation with Iron(III) Hydroxide

“…The application of Pb·Spec to the on-line preconcentration and separation of lead from iron in FI-FAAS has so far been reported for the determination of lead in iron and steel. 30 The high selectivity of Pb·Spec resin enabled us to preconcentrate and separate lead from a large amount of iron(III) in the sample solution after coprecipitation. The concentration of nitric acid in the sample solution to be subjected to the FI-ETAAS was adjusted to 1 mol l -1 , because it is most suitable for lead adsorption on Pb·Spec resin.…”

On-line Preconcentration and Determination of Traces of Lead in River-water and Seawater by Flow Injection-Flame Atomic Absorption Spectrometry and ICP-Mass Spectrometry

“…14 The high k′ and high selectivity for lead(II) on Pb·Spec prompted us to use the resin for the effective separation and preconcentration of Pb(II) in FI-AAS determination of lead in steel. 7 In this work, we tried to extend the applicability of the adsorbent to the FAAS and ICP-MS determination of traces of lead in river-water and seawater. Strontium(II) is somewhat more weakly adsorbed on Pb·Spec TM than lead(II).…”

“…In the previous work, 7 5 µg of lead(II) was quantitatively retained on a Pb·Spec TM column (7.5 mm i.d. × 100 mm) and eluted with 0.1 M ammonium oxalate solution.…”

“…[2][3][4][5][6] The advantages of the combination of FI on-line preconcentration with spectrometry have been reviewed in the previous paper. 7 Various adsorbents have so far been reported for the on-line preconcentration of lead (and other heavy metals) in water samples. For example, 8-hydroquinoline immobilized onto silicone tubing 8 or microporous silica, 9 poly(L-cysteine) immobilized controlled-porous glass, 10 a highly cross-linked macroporous iminodiacetate resin (Metpac CC-1, Dionex) 11 and dealginated seaweed 12 have been used for the on-line preconcentration of lead in water samples prior to the ICP-MS determination of lead.…”

“…Pb·Spec TM exhibits high selectivity to lead(II) and shows no affinity for the alkali metal ions and other heavy metal ions, 14 therefore, the resin has been successfully applied by the present authors to preconcentration of lead in steel by an FI technique. 7 This work was undertaken to extend the excellent utility of Pb·Spec TM to the precise determination of traces of lead in river-water and seawater by FI on-line preconcentration coupled with flame atomic absorption spectrometry (FAAS) or ICP-mass spectrometry (ICP-MS).…”