tubes were centrifuged (10,000 rpm for 10 min) to separate the
aqueous and hexane phases. Concentration of diesel in the hexane
extract was measured spectrophotometrically at 295 nm. By using
the calibration curve of the crude diesel in hexane, concentration of
the solubilized diesel was determined. Experiments were performed
in triplicates. Control experiments were also run in parallel
where no biosurfactant were added to the assay sample before
extraction with hexane. Results are expressed as percentage of
solubilization calculated according to the following formula:
Solubilizationð%Þ ¼ Dassay Dcontrol
Dinitial
100
where Dassay is the concentration of diesel in the hexane extracts of
assay samples; Dcontrol is the concentration of diesel in control experiments
and Dinitial is the initial concentration of diesel before
solubilization test.