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Thin Layer chromatographic analyses of pesticides in a soil ecosystem


S Afful
SA Dogbe
K Ahmad
T Ewusie

Abstract

Silica gel 60, silica gel 60 F254, and aluminium oxide as adsorbents were used to investigate their suitability for the analysis and detection of the pesticides: nitrofen, atrazine, diuron, dioxacarb, propoxur, propanil, carbaryl and cypermethrin in soil ecosystem using ethyl acetate, chloroform, dichloromethane and ethyl acetate/chloroform (1:1) as developing solvents. O-tolidine and potassium iodide reagent were used for the detection of the pesticides. Rf values obtained for the pesticides using the silica gel 60-ethyl acetate, silica gel 60 F254-ethyl acetate, silica gel 60-chloroform, silica gel 60 F254-chloroform, silica gel 60 – (1:1) ethyl acetate/chloroform and silica gel 60 F254 – (1:1) ethyl acetate/chloroform systems generally were within the stipulated range of 0.4 –0.8. Rf values obtained for the pesticides using silica gel 60-dichloromethane and silica gel 60 F254-dichloromethane systems were very low except for cypermethrin and nitrofen. Analysis with aluminium oxide coated plates gave a heavy yellow background with the detection reagent making visualization of spots difficult. Aluminium oxide coated plate is, therefore, not recommended when o-tolidine plus potassium iodide is used as detection reagent.