Detection of chlorinated pesticides on the surface of fungus using ToF-SIMS

Chlorinated organic compounds are commonly used as pesticides (e.g. Lindane or DDT); unfortunately these compounds have the ability to be concentrated in aquatic and terrestrial food chains causing environmental problems due to their toxicity. Therefore there is a need for their removal using wastewater treatment plants. It is known that these pollutants adsorb on to the surface of the fungi Rhizopus arrizus from a water solution. However the actual mode of biosorption is unknown. We aim to investigate this interaction further using time-of-flight (ToF)-SIMS. Samples of fungus were grown in aqueous solutions containing Lindane then freeze-dried, the presence of Lindane was independently quantified by a gas chromatography-electron capture detector technique. The samples were then subjected to ToF-SIMS analysis. Evidence for Lindane was seen on the surface of the fungus, however it became apparent that the Lindane was too volatile for such an analysis. This rapid deterioration of signal is preventing a more in depth study of the interaction between Lindane and R. arrhizus. However it is anticipated that by utilising a frozen-hydrated sample preparation technique, of a type currently being developed at UMIST, that these challenges would be overcome.