Simultaneous electrochemical detection of carcinogenic polycyclic aromatic amines in environmental samples using single-walled carbon nanotube-gold nanoparticle composite

A nanocomposite was prepared using single walled carbon nanotubes (SWCNTs) and thiol-derivatised gold nanoparticles (Auₙₐₙₒ₎. Transmission electron microscopy (TEM) image of the nanocomposite showed that the Auₙₐₙₒ were self-assembled on to the side walls of the SWCNTs after the modification process. Moreover, from the TEM analysis, it was clear that the likelihood of agglomeration of these nanoparticles in the nanocomposite were rare. A film of the nanocomposite was then applied on a glassy carbon electrode (GCE). The nanocomposite modified GCE was used for the electrochemical detection of several carcinogenic polycyclic aromatic amines (PAAs) simultaneously. The combination of the adsorptive properties of SWCNTs with an enhanced electroactive surface area, electrical conductivity of Auₙₐₙₒ, together with the interaction of the amino group of the analytes and Auₙₐₙₒ permitted very efficient detection of the analytes. Preconcentration and detection of the analytes in the real samples could be achieved in a single step using adsorptive stripping voltammetry (ASV). ASV for the PAAs achieved detection limits in the range of 1 μg L⁻¹ (using 9,10-diaminophenanthrene as an example), with linearity up to 3 orders of magnitude. Moreover, the nanocomposite modified electrode exhibited excellent selectivity with high reproducibility towards several PAAs and resulted in their simultaneous and sensitive detection with detection limits in the μg L⁻¹ range. Using 9,10-diaminophenanthrene as an example, the reproducibility of the analyte signal in the simultaneous detection of several PAAs was determined to be within 5% (n = 8) from one electrode preparation to another, and the response signal was stable (±4.5% at 95% confidence interval) for 15 repeated analyses with 600 s of preconditioning. Applicability of the procedure to tap water, river water, and wastewater samples was demonstrated. Such nanocomposite devices hold great promise for convenient and sensitive environmental screening of carcinogenic PAAs.