EN
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%.