APPLICATION OF C-18 DISKS FOLLOWED BY GAS-CHROMATOGRAPHY TECHNIQUES TO DEGRADATION KINETICS, STABILITY AND MONITORING OF ENDOSULFAN IN WATER

A comparative degradation study of endosulfan spiked at 35 mu g/l in w ater using photocatalysis with (FeCl3/H2O2)/ (TiO2/H2O2) and photolysi s using either a xenon are lamp and/or sunlight was performed. After i rradiation the water samples were preconcentrated using C-18 solid-pha se disk extraction and analysis by gas chromatography-electron capture and mass spectrometric detection. Endosulfan sulphate was found in th e photodegradation studies. Endosulfan showed high stability in water when it was exposed to sunlight and xenon are lamp, but by means of ph otocatalysis with FeCl3/H2O2, TiO2/H2O2, the degradation was very fast with half lives varying from 59-98 min. The degradation kinetics foll owed a first order reaction and the R.S.D. of rate constants, for n=3, varied from 4-17%. The stability of endosulfan on C-18 Empore disks h as been determined at 20 degrees C, 4 degrees C and -20 degrees C for periods up to 3 months. Endosulfan was not degraded on C-18 Empore dis ks. Ground water samples from south of Spain (Almeria) were monitored during 1 year. The compounds alpha-, beta- and endosulfan sulphate wer e detected at concentration values varying from 0.5-540 ng/l. (C) 1998 Elsevier Science B.V.