Mireille Consalvey PhD Thesis - University of St Andrews

( hapt
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acetone and DMF do not differ (Honcywill 2001) or differ by 3% (Porra et al.
1989). It was therefore decided that if the solvents exhibited similar extraction
efficiencies that a3% difference would be deemed to be an acceptable level of
error in relation to other inherent errors associated with the solvents e. g.
evaporatability etc.
Honeywill (2001) conducted a comparative study to compare the
extraction efficiencies, notably for chlorophyll a, of acetone and DMF and found
no significant difference in the amount of chlorophyll a extracted by acetone and
DMF from microphytobenthic samples and concluded that results from either
extraction are comparable. Wright et al. (1997) showed either no difference or
better extraction of chlorophyll a by DMF in phytoplankton samples.
2.6.4. High Perfon-nance Liquid Chromatography (HPLC)
The HPLC system (Figure 2.5) consisted of a quaternary high-pressure
pump (Perkin-Elmer 410), an autosampler (Waters WISP 417), a Diode Array
Detector (Waters 910), a then-nostat and an oven containing a reverse phase
Nucleosil C 18 column (Capital HPLC Ltd). The oven was set to 25 'C and the
Autosampler cooled to 4 'C. The Autosampler was programmed to inject 70 ýd
of sample with 30 gi of distilled water onto the column (to give greater clarity of
peaks; after Honeywill 2001). Samples were run using one of two gradient
protocols. Each sample takes the length of the gradient run plus a3 min pre-
injection sequence.
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