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Title: Development and application of ToF-SIMS within agrochemistry
Author: Converso, Valerio
ISNI:       0000 0004 7658 644X
Awarding Body: Imperial College London
Current Institution: Imperial College London
Date of Award: 2018
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This study is aimed at exploring the potential use of Time of Flight-Secondary Ion Mass Spectrometry (ToF-SIMS) for the detection and localization of agrochemicals in biological material. The first part focused on developing a method (from sample preparation to ToF-SIMS analysis) for the analysis of a selection of 44 commonly and commercially used agrochemicals. Based on the results of these analyses, a model compound was chosen for further investigation. The chosen compound was the fungicide fludioxonil and both limit of detection and quantification were calculated for its ToF-SIMS detection. Further experiments were performed on how endogenous molecules could affect the ToF-SIMS detection of fludioxonil and, in particular, the "matrix effect" of components typically present in biological matrices was studied. After proving the capabilities of the technique in a simplified experimental setting, ToF-SIMS was used to analyse real-life complex biological samples. The first targets of the analyses were nematodes, important agricultural pests. Extensive work focused on developing a reproducible sample preparation in order to obtain thin sections of nematodes. Unfortunately, none of the tried techniques gave good results. On top of this, fludioxonil was not detectable in any of the analysed nematodes. For this reason, another biological sample was explored for ToF-SIMS analyses: formulation coated wheat seeds. After developing a reproducible sample preparation method for sectioning the seeds, ToF-SIMS analyses were able to detect fludioxonil in all the sections. Overall, this study demonstrated the potential use of ToF-SIMS in the agrochemical industry. Its capability of obtaining visual information on the distribution of specific active ingredients in real-life biological samples at realistic concentrations makes this technique potentially valuable in agrochemical research, even though its limitations mean that its applications in the agrochemical industry are likely to be fairly specific and limited.
Supervisor: Bundy, Jacob G. ; Flemming, Anthony J. Sponsor: European Union
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral