Compared with the off-line clean-up, the SPLE approach
gave 89 and 87% recovery as a mean of all pesticides for the
A1 and A2 soils, respectively. Statistical evaluations (F-test and
t-test) of the results obtained by the two approaches revealed no
significant difference at 5% level except in the case of p,p-DDE
in both soil samples, -endosulfan (A2 soil) and -endosulfan
(A1 soil). This result demonstrates promising feature of the current
approach. To further explore the applicability of SPLE to
other OCPs, a certified reference soil sample (CRM 811-050)
containing 13 OCPs was extracted. The results from this investigation
are presented in Table 2.