## 3 Results
### IT-SPME Coupled to Cap-LC
#### 3.1.3 Reproducibility and Specificity  
In order to study the reproducibility, three consecutive injections of the tested compounds were affected in the chromatographic system (with the separative column placed between the IT-SPME device and the detector) and using a sample volume of 200 \(\upmu\)L. As an example, in Figure 2a are shown the chromatograms obtained for naphthalene and fluoranthene. The relative standard deviations (RSDs) were calculated from the peak areas measured for each compound ((standard deviation/mean area) \(\times\) 100). The values found with the synthetized capillaries are summarized in Table 2, which also shows the values obtained for the commercial capillary that provided best extraction efficiency for each compound.  
The results of Table 2 show that the synthetized TEOS-MTEOS reinforced with NPs capillaries provided reproducibility suitable and comparable to that achieved with commercial capillaries. No significant differences on the reproducibility obtained between the two synthetized capillaries were found.  
The specificity was also tested for two different matrices of interest in the environmental field, in order to investigate whether matrix components could interfere with the identification or quantification of the analytes. The samples selected were water (ditch and river water) and the extract obtained from a soil sample (0.3 g) treated with 1.2 mL of acetone in an ultrasonic bath, and the PAHs naphthalene and fluoranthene were selected as model compounds. The water samples were filtered before being loaded into the chromatographic system, whereas the extract of soil was evaporated to dryness, and then reconstituted with water and filtered before being processed. In Figure 2b are shown the chromatograms obtained for some of the samples assayed using the optimized IT-SPME conditions (PS-DVB capillary).  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Compound** & **Concentration(\(\upmu\)g/mL)** & **Extractive Phase** & **RDS (\%)** \\ \hline \multirow{3}{*}{Saccharine} & \multirow{3}{*}{125} & TEOS-MTEOS/SiO\({}_{2}\) NPs & 6 \\  & & TEOS-MTEOS/TiO\({}_{2}\) NPs & 4 \\  & & FFAP & 9 \\ \hline \multirow{3}{*}{Naphthalene} & \multirow{3}{*}{20.0} & TEOS-MTEOS/SiO\({}_{2}\) NPs & 4 \\  & & TEOS-MTEOS/TiO\({}_{2}\) NPs & 9 \\  & & PS-DVB & 8 \\ \hline \multirow{3}{*}{Fluoranthene} & \multirow{3}{*}{1.0} & TEOS-MTEOS/SiO\({}_{2}\) NPs & 4 \\  & & TEOS-MTEOS/TiO\({}_{2}\) NPs & 7 \\ \cline{1-1}  & & PS-DVB & 2 \\ \hline \hline \end{tabular}
\end{table}
Table 2: Reproducibility obtained by IT-SPME–Cap-LC with the trimethoxyethylsilane (TEOS-MTEOS) capillaries functionally with nanoparticles (NPs) and the commercial capillary that gave the best extraction rate for each compound (n = 3); volume of sample processed, 200 \(\upmu\)L.  
As observed in the above figure, no significant differences between the registers obtained for nanopure water and for the water samples were observed. Thus, the specificity for this kind of samples was considered satisfactory. A minor peak was observed in the solid extract; the intensity of such peak was much lower in the spiked soil sample. These differences could most probably be minimized by reducing the soil particle size. Nevertheless, as the aforementioned peak eluted at a retention time different to those of the analytes, it was concluded that the specificity for the solid extracts was also suitable.