The experimental design showed that the pH is not significant at the 95% confidence level when varied from 5.0 to 1.0 (Fig. 2). The degree of result reproducibility (Table 4) demonstrates the robustness of the method.
3.3. Application of SDME method
The developed SDME method was applied using field collected water samples and the data are presented in Table 5 and Table 6. Fig. 7 shows the chromatogram obtained from the real samples in this study. The water sample used in testing this method were collected from an irrigation area in Propria and river water from the banks of San Francisco River in Propria city. The selected pesticides in this study are widely used in this rice cultivation field. Also tap water samples in two cities Propria and Aracaju in Sergipe were collected.
Table 5.