Optimization of a procedure for the simultaneous extraction of polycyclic aromatic hydrocarbons and metal ions by functionalized and non-functionalized carbon nanotubes as effective sorbents

In this publication, a new dispersive solid-phase extraction (dSPE) method combined with gas chromatography-mass spectrometry and atomic absorption spectrometry was developed for the simultaneous determination of 9 PAHs and chromium, cadmium, and lead ions in water samples. For this purpose, non-modified multi-walled carbon nanotubes (MWCNTs) and modified -MWCNTs (OH-MWCNTs and COOH-MWCNTs) were used as sorbents. Parameters affecting the extraction, such as the amount of sorbent, the pH of the sample, the composition and volume of eluents and the extraction time were optimized. Sequential elution was applied using 6 mL of dichloromethane for the elution of PAHs and 5 mL of 3 M HNO3 for cadmium, lead, and chromium. The optimal values of other parameters were as follows: 50 mg of sorbent per 250 mL of water sample, pH in a range from 6 to 7 and 30 min of contact time between the sorbent and analytes. The results demonstrated the high extraction capability of modified MWCNTs with recoveries between 80 and 101% for cadmium, chromium, and lead ions and between 83 and 92% for PAHs. Finally, the optimized method was validated, and the matrix effects were determined.