Research Publications (Applied Sciences)
Permanent URI for this collectionhttp://ir-dev.dut.ac.za/handle/10321/213
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Item An evaluation of the efficacy of using selected solvents for the extraction of lipids from algal biomass by the soxhlet extraction method(Elsevier, 2013-08-14) Ramluckan, Krishan; Bux, Faizal; Moodley, Kandasamy G.The use of solvents for the extraction of lipids from algal biomass has been a method of choice for many years. The soxhlet extraction method was chosen because of its simplicity in operation, relative safety and potential for upscaling to industrial plant level. The source of algal biomass was a raceway pond. Chlorella sp. which is known to produce larger amounts of oil than other indigenous species was used for this investigation. Thirteen solvents spanning a range of polarities and solubilities were selected for this study. Extraction methodology involved the use of single solvents, selected binary solvent mixtures and time-based extractions which were varied from 1 to 5 h. Ultraviolet (UV) spectroscopy was used to determine chlorophyll content of the lipid extracts and gas chromatography was used for the identifica-tion and quantitation of the lipids. Analysis showed that ethanol, chloroform and hexane were generally more efficient in the extraction of lipids than the other solvents studied, producing lipid contents in excess of 10%. The time-based trials indicated that the optimum extraction time was 3 h for the solvents selected. The binary solvent mixture with the greatest extraction efficiency (i.e. >10% lipid extract) was obtained with the 1:1 mixture of chloroform:ethanol. Chlorophyll quantities varied for each solvent extract with chloroform and methanol producing the highest values at >1%. Chromatography was effec-tive in identifying lipids used in the production of biodiesel.Item A rapid method for determining chlorobenzenes in dam water systems(Africa Journals Online, 2012-01-01) Moodley, Kandasamy G.; Chetty, Deenadayalan Kisten; Ramphal, Sayjil Rohith; Gericke, G.A method using direct immersion solid phase microextraction (DI-SPME) coupled to gas chromatography equipped with a flame ionisation detector (GC-FID) was developed for the analysis of 7 chlorinated benzenes in dam water. The main parameters affecting the DI-SPME process were optimised. The optimised method comprises the use of a 100 µm polydi-methylsiloxane (PDMS) fibre coating; 5 mℓ sample size; 700 r/min rate of agitation and an extraction time of 30 min. The calibration curve was linear with correlation coefficients ranging from 0.9957–0.9995 for a concentration range of 1–100 ng/mℓ. The limits of detection and quantification ranged from 0.020–0.265 ng/mℓ and 0.204–2.65 ng/mℓ, respectively. Recoveries ranged from 83.6–107.2% with relative standard deviation of less than 9.2%, indicating that the method has good precision. The method is reliable and is free of matrix interferences. Water samples collected from Grootdraai Dam were analysed using the optimised conditions to assess the potential of the method for trace level screening and quantification of chlorobenzenes. The method proved to be efficient, as 1,3 dichlorobenzene, 1,4-dichlorobenzene and pentachlorobenzene were detected at concentrations of 0.429 ng/mℓ, 1.685 ng/mℓ and 1.433 ng/mℓ, respectively.