Spurenbestimmung von Insektiziden in Sedimenten und Böden aus dem Einzugsgebiet des Lake Abaya / Äthiopien

Method validation for trace analysis of fifteen insecticides, mainly organochlorine insecticides, in the µg kg -1 -range in sediment cores and soils from the Lake Abaya watershed, one of the great lakes in the Ethiopian rift valley, was carried out. Extraction methods studied were ultrasonic extraction (USE), Soxhlet extraction and pressurized solvent extraction
(PSE/ASE). Determinations were carried out using GC-MS. Hexane, dichloromethane,
hexane/ acetone (1/1, v/v) und ethylacetate/ methyl-tert-butylether (1/3, v/v) were used as solvents. Matrix effects were identified in quantification and discussed. Due to good analyte recoveries and a low yield of undesired matrix compounds coextracted from the samples, ultrasonic extraction with dichloromethane as solvent was used for sample analysis. The method was validated using a certified reference material. Values measured were in good
agreement with the certified values. A contamination of the Lake Abaya region with the insecticide DDT and its metabolites DDD and DDE was found at concentrations between 1,6 µg kg -1 and 3390 µg kg -1 .