COMPARISON OF SUPERCRITICAL-FLUID EXTRACTION AND SOXHLET EXTRACTION FOR THE DETERMINATION OF DDT, DDD AND DDE IN SEDIMENT

Sediment containing incurred DDT, DDD and DDE residues was extracted u sing supercritical fluid (CO2) extraction (SFE) and Soxhlet extraction . The two extraction techniques were compared. Samples were collected from the Pongolo floodplain in KwaZulu-Natal and the Letaba River in M pumulanga, South Africa. The sediment samples were freeze-dried, sieve d, extracted and analysed by GC-MS for their DDT, DDD and DDE content. Validation of the GC-MS method was done against a reference standard. The paired t-test and two-way analysis of variance (ANOVA) without re plication were used for the statistical evaluation of the two extracti on techniques. Results of the paired t-test and two-way ANOVA showed t hat there is no evidence that SFE differs significantly from Soxhlet e xtraction for the determination of the three compounds, SFE can be use d to replace Soxhlet extraction for the extraction of DDT, DDD and DDE from sediment. The determined limits of detection (LODs) were lower t han the calculated suggested EP-based SQC for DDT, DDD and DDE making GC-MS coupled to SFE a useful method for the determination of the thre e compounds in sediment