60 research outputs found
Molecular interconversion behaviour in comprehensive two-dimensional gas chromatography
Comprehensive two-dimensional gas chromatography (GC x GC) is shown to provide information on dynamic molecular behaviour (interconversion), with the interconversion process occurring on both columns in the coupled-column experiment. The experiment requires suitable adjustment of both experimental conditions and relative dimensions of each of the columns. In this case, a longer column than normally employed in GC x GC allows sufficient retention duration on the second column, which permits the typical plateau-shape recognised for the interconversion process to be observed. The extent of interconversion depends on prevailing temperature, retention time, and the phase type. Polyethylene glycol-based phases were found to result in high interconversion kinetics, although terephthalic acid-terminated polyethylene glycol had a lesser extent of interconversion. Much less interconversion was seen for phenyl-methylpolysiloxane and cyclodextrin phases. This suggests that for the oximes, interconversion largely occurs in the stationary phase. Examples of different extents of interconversion in both dimensions are shown, including peak coalescence on the first column with little interconversion on the second column
Characterization of Annona cherimola mill. Seed oil from Madeira Island: a possible biodiesel feedstock
The possibility of using Annona seed oil as an
added value product, namely as a source of biodiesel, is
explored. Milled Annona seeds were extracted with hexane
at room temperature (72 h) and at solvent boiling point
(6 h). Oil content was found to be 25 and 22.4% respec tively. The oil was characterized in terms of lipid compo sition (HPLCâAPCIâMS and 13C NMR), resistance to
oxidation and acidity index. FAME composition was
determined by GCâMS and five major peaks were identi fied. Production of biodiesel from Annonaâs seed oil was
achieved by base-catalyzed transesterification. Density,
viscosity, refraction coefficient, acid value, cold filter
plugging point, cloud point and oxidation stability were
measured. The iodine value and the ââapparent cetane
numberââ were calculated. Density, viscosity, acid value,
iodine value, cold filter plugging point and cloud point
were within EN14214 specifications and the calculated
ââapparent cetane numberââ was also indicative of a suitable
product.info:eu-repo/semantics/publishedVersio
Biodiesel Production from Spent Frying Oil of Fish via Alkali-catalyzed Transesterification
Gas Chromatographic Separation and Identification of Jacaric and Punicic 2-Ethyl-1-Hexyl Esters
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