Analytical methods and instrumentation for the determination of organophosphorus pesticides in fruit and vegetable substrates

Dehzoei, AM

Abstract

The chromatographic behaviour of four organophosphorus pesticides has been
investigated, using capillary gas liquid chromatography-mass spectrometry (GC-MS), and
packed and wide bore capillary gas liquid chromatography with electron capture detection
(GC-ECD).
The first part of this thesis (Chapter 3) embodies the application of high performance
capillary gas liquid chromatography-mass spectrometry and the development of the
methodology for analysis of pesticides in fruit and vegetable substrates. Manipulation of
GC-MS data during the sample analysis is necessary in order to eliminate the problems
arising from the complexity of the samples.
The application of selected ion monitoring (SIM) in GC-MS is to a large extent limited
by selection of the ion for monitoring, selection of internal standard, optimisation of
electrometer zero, the electron multiplier voltage, the selected mass interval, column
selection for GC-MS analysis and tuning of the quadrupole GC-MS. A major concern
was with the determination of the optimum conditions for the analysis of substrates
containing organophosphorus pesticides by GC-MS following solvent extraction (without
clean up steps). The analysis of organophosphorus samples using GC-MS-SIM provides
detection limits lower than Pg pesticide injected and very good recovery data.
The second part (Chapter 4) deals with the application of GC-ECD. Here the role of
packed column support, packed and wide bore capillary column temperature and detector
temperature was investigated. Comparisons of the relative responses of the pesticides
analysed (i) on packed columns and (ii) on wide bore capillary column under different
column and detector cell temperatures were undertaken and the optimal condition for each
of the organophosphorus pesticides was determined, under the optimal conditions the
detection limits and recovery for fruit and vegetable samples were examined. The results
from this method were correlated with the data obtained by GC-MS and found to be in
very good agreement. The data obtained from analysis using GC-ECD was found to have a higher precision than
that obtained by GC-MS, however GC-MS exhibited a higher selectivity for the
determination of these pesticides.

Citation

Dehzoei, A. Analytical methods and instrumentation for the determination of organophosphorus pesticides in fruit and vegetable substrates. (Thesis). University of Salford

• Thesis Type: Thesis
• Deposit Date: Sep 22, 2011
• Publicly Available Date: Sep 22, 2011
• Award Date: Jan 1, 1991