Solid-phase microextraction of heavy metals in natural water with a polypyrrole/carbon nanotube/1, 10-phenanthroline composite sorbent material.

A simple and sensitive method for simultaneous microextraction and determination of heavy metals using a new direct immersion solid-phase microextraction (DI-SPME) sorbent material combined with inductively coupled plasma mass spectrometry (ICP-MS) was investigated. In this method, sorbent coating composites were prepared by simultaneous electropolymerization of pyrrole on pencil lead in the presence of carbon nanotubes (CNTs) and different metal chelating ligands. Among the coatings evaluated, a polypyrrole coating with entrapped CNTs and the chelator 1, 10 phenanthroline allowed the determination of silver, cadmium, cobalt, iron, nickel, lead, and zinc. Parameters influencing microextraction efficiency including pH, extraction time, and desorption time were optimized. The linear dynamic ranges were 1-1000 μg L-1 for Ag, 1-750 μg L-1 for Cd, Pb, and Zn, and 1-500 μg L-1 for Co, Fe, and Ni with limits of detection of 0.012-0.163 μg L-1 and limits of quantification of 0.039-0.542 μg L-1. The relative standard deviations (RSDs, n = 5) ranged from 1.85% to 5.01%. The effect of inorganic interferences on the determination of the heavy metals also was examined and finally, the method was successfully applied for the determination of heavy metals in real water samples.