The overall objective of this thesis was to develop field deployable instrumentation for the
selective, sensitive determination of additives in diesel fuels using flow injection with
chemiluminescence detection. The target analytes were the detergent dodecylamine and the
lubricity additive P655.
Chapter One describes the types of additives that are used in fully formulated diesel fuels in
order to improve performance and outlines the need for robust analytical methods to be able to
detect their presence / absences in fuels at the point of distribution, i.e. at the petrol pump.
Flow injection (FI), and chemiluminescence (CL) are described as suitable techniques for
sample preparation and detection respectively. The application of FI-CL for the quantitative
determination of various analytes is reviewed, with the focus on real sample matrices. Finally
the technique of solid phase extraction is discussed as a means of selective analyte
preconcentration / matrix removal prior to FI-CL detection
Chapter Two describes the development and optimisation (both univariate and simplex) of an
FI-CL method for the determination of dodecylamine in acetonitrile / water mixtures using the
catalytic effect of amines on the peroxyoxalate / sulphorhodamine 101 CL reaction. The linear
range for dodecylamine was 0 - 50 mg Lˉ¹ with a detection limit of 190 µg Lˉ¹ and RSDs
typically < 4 %. The effect of indigenous diesel compounds on the CL response is also
investigated.
Chapter Three investigates the applicability of the method developed in Chapter Two to
determine dodecylamine in diesel fuels. Solid phase extraction was needed prior to analysis by
FI-CL. The development of a solid phase extraction that is compatible with the FI-CL system
is detailed. GC-NPD and GC-MS analysis are used in order to validate the solid phase
extraction procedure. A range of diesel fuels have been spiked with an additive package
containing dodecylamine and have been analysed off-line using FI-CL. Recoveries for all
diesel fuels analysed were < 72 % and all fuels could by identified from the corresponding
base fuel.
Chapter Four describes the design and construction of a fully automated on-line solid phase
extraction flow injection chemiluminescence analyser for the determination of dodecylamine
in diesel fuel. Details of the automation and programming using LabVIEW are described.
Results obtained using the automated on-line system are compared with results obtained using
off-line SPE with FI-CL detection from Chapter Three. Recoveries for all fuels except SNV
were < 71 %, and all fuels except SNV could be positively identified from the corresponding
base fuels. No significant differences were found between the on-line and off-line results
(within 95 % confidence limits).
Chapter Five investigates the feasibility of determining the lubricity additive P655 in diesel
fuel using FI-CL. The optimisation and development of a method using the competing
reactions of periodate with alcohols and periodate with the CL oxidation reaction with
pyrogallol is discussed, and the development of a solid phase extraction procedure for the extraction of P655 from an organic matrix is described. The limit of detection for P655 using SPE without preconcentration was 860 mg Lˉ¹ and was linear in the range 0 - 10000 mg Lˉ¹ (R² = 0.9965).
Date of Award | 2002 |
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Original language | English |
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Awarding Institution | |
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DETERMINATION OF ADDITIVES IN FUELS USING AUTOMATED FLOW INJECTION ANALYSIS WITH CHEMILUMINESCENCE DETECTION
FLETCHER, P. J. (Author). 2002
Student thesis: PhD