Synopsis A pre-concen&ration method for extracting organochlorines from seawater~Gsemployed to analuse IDDTs and PCBs. The sampling device and the conditions for optimal adsortion performance are described.Recovery tests with spiked solutions were made before applying the method on real samples. Working up of the samples prior to gas chromatographic analysis~ precautions and advantages of the procedure are also discussed. The application of the method for seawater~ containing very low levels of

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... oY'ganochlorines~ is shown by data fr om equatorial surface waters . The average level for ~DDT ana PCBs was 0.21 ng/l and 0. 37 ng/l . The overall ?recision of the method is about ± 15% with a lower limit of detection of 0.1 ng/l-for PCBs and 0.05 ng/l-l for IDDT. Descriptors: DO T, PC8s, Analysis in Equatoriai Atiantic ':>€-awi"lter, Pre-concentra~ i o"'" ,e.:..~r.:a~es n resins. Desc r i t ore 5: DOT , PC Es , Anã 1 i s e na ã gua dn ma r oc.' A t 1 ân t ; co E qua t () r i a 1 , Tê,: n i Ci'l ~ C t-D r L' -(C'net.:· -,: r al ~c: eif' r (: S ; "I,"! <; •