Oriented ZnO nanorods grown on a porous polyaniline film as a novel coating for solid-phase microextraction

• Oriented ZnO nanorod arrays were in situ hydrothermally grown on porous polyaniline.
• This composite was developed as a novel solid phase microextraction coating.
• A sensitive and reliable method for BTEX analysis in natural water was developed.

In this work, oriented ZnO nanorods (ZNRs) were in situ hydrothermally grown on a porous polyaniline (PANI) film to function as a solid-phase microextraction (SPME) coating. Scanning electron microscopy (SEM) study revealed that the majority of oriented ZNRs grew from pores of PANI matrix, which protected the ZNRs from easily peeling off during operation. Furthermore, in this process, a thin layer of PANI was found to cover the ZNRs, which can enlarge the effective surface area of the composite coating. This ZNRs/PANI composite coating combined the merits of both ZNRs and PANI and, thus, has several advantages over that of sole PANI film and ZNRs coating such as improved extraction efficiency for benzene homologues, enhanced mechanical stability and longer service life (over 150 cycles of SPME-GC operation). Coupled with gas chromatography-flame ionization detector (GC-FID), the optimized SPME-GC-FID method was used for the analysis of six benzene homologues in water samples. The calibration curves were linear from 1 to 1000 μg L−1 for each analyte, and the limits of detection were between 0.001 and 0.024 μg L−1. Single fiber repeatability and fiber-to-fiber reproducibility were in the range of 1.3–6.8% and 5.3–11.2%, respectively. The spiked recoveries at 100 and 5 μg L−1 for three environmental water samples were in the range of 79.8–115.4% and 73.7–117.4%, respectively.