Since the inception of analytical supercritical fluid extraction (SFE) in the early 80's, this technique has garnered great attractions in the
extractions of variety of analytes from variety of matrices. In this study.
supercritical carbon dioxide (SC CO2) has been examined as a sample
preparation method for the extraction of eugenol from plant matrix prior to
high performance liquid chromatography (HPLC) analysis and for the
extraction of organochlorine pesticides (OCPs) from sewerage sludges and
chlorpyrifos from formulation and soil samples prior to capillary gas
chromatography (GC) analysis. This is an area of considerable interest as
many current methods use environmentally hazardous chlorinated solvents
and alternative methods are required. Although numerous studies have examined the potential application
of SFE to isolate pesticides and plant products, the work has been
qualitative rather than quantitative. The present work describes studies
which have examined the supercritical conditions needed for complete
extraction of the pesticides and plant product eugenol. Initially a complex
matrix sludge was chosen. Later a simple matrix soil was chosen and a
single pesticide chlorpyrifos was used as the SFE of sludge was
unsuccessful. In the extraction of chlorpyrifos problems were encountered
in the trapping of the extract on depressurisation of the SC CO2. The effect
of collection solvent, CO2 flow rate, solvent depth, and restrictor heating
on the trapping efficiency have been investigated. Two methods of
trapping were evaluated. Once a quantitative trapping method was established, the effect of different soil matrices on the recovery of
chlorpyrifos at different chlorpyrifos spiking level was investigated. The
SFE of soil was compared to Soxhlet extraction.
A Doctoral Thesis. Submitted in partial fulfilment of the requirements for the award of Doctor of Philosophy of Loughborough University.