A solid-phase microextraction sorbent composite was developed using the sol-gel technique. The multi-walled carbon nanotubes (MWCNTs) were added to a nanocomposite and the homogeneous, doped composite was injected into a polypropylene hollow fiber. This device has been applied for the determination of three nitro aromatic compounds, including m-nitroaniline (NA), nitrobenzene (NB) and p-nitrotoluene (NT), in environmental waters via direct immersion hollow fiber solid-phase microextraction (HF-SPME) and high performance liquid chromatography-photodiode array detector (HPLC-PDA). The results illustrated that this new technique is a simple and reliable method for SPME device preparation: the prepared sorbent did not swell in organic solvents and possessed high mechanical strength; the SPME device employed was not fragile because of the polypropylene protector fiber; and, the fiber was disposable such that no carry-over effects were present. A homemade, pre-heating electrical device was designed for the back-extraction and pre-concentration of the analytes and was utilized before the HPLC injection step. Using this trap significantly increased the efficiency and analyte pre-concentration factors. In optimal conditions, the detection limits of the analytes varied between 0.1 and 3.0 ng mL-1 (n=8), precision was in the range of 0.41–4.19% (n = 3) and linear ranges were within 1.0 - 1000 ng mL-1 for m-nitroaniline; 0.5 - 1000 ng mL-1 for nitrobenzene and 5.0 - 1000 ng mL-1 for p-nitrotoluene. The method was successfully applied to the analysis of environmental water samples with recoveries from 87.9 to 96.1%.

Keywords