Selective dispersive micro solid-phase extraction using oxidized multiwalled carbon nanotubes modified with 1,10-phenanthroline for preconcentration of lead ions

• Modified ox-MWCNTs using 1,10-phenanthroline as a selective sorbent in DMSPE.
• High capacity and small LOD found using cationic chelate complex with 1,10-phenanthroline.
• Using F-AAS and ET-AAS for the determination of Pb(II).
• Application to determination of lead content of fish samples.

A dispersive micro solid phase extraction (DMSPE) method for the selective preconcentration of trace lead ions on oxidized multiwalled carbon nanotubes (ox-MWCNTs) with complexing reagent 1,10-phenanthroline is presented. Flame and electrothermal atomic absorption spectrometry (F-AAS, ET-AAS) were used for detection. The influence of several parameters such as pH, amount of sorbent and 1,10-phenanthroline, stirring time, concentration and volume of eluent, sample flow rate and sample volume was examined using batch procedures. Moreover, effects of inorganic matrix on recovery of the determined elements were studied. The experiment shows that foreign ions did not influence on recovery of the determined element. The method characterized by high selectivity toward Pb(II) ions. Lead ions can be quantitatively retained at pH 7 from sample volume up to 400 mL and then eluent completely with 2 mL of 0.5 mol L−1 HNO3. The detection limits of Pb was 0.26 μg L−1 for F-AAS and 6.4 ng L−1 for ET-AAS. The recovery of the method for the determined lead was better than 97% with relative standard deviation lower than 3.0%. The preconcentration factor was 200 for F-AAS and 100 for ET-AAS. The maximum adsorption capacity of the adsorbent was found to be about 350 mg g−1. The method was applied for determination of Pb in fish samples with good results. Accuracy of the method was verified using certified reference material DOLT-3 and ERM-BB186.

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