Wyniki wyszukiwania - BazTech

Ograniczanie wyników

1 Acta Chromatographica

1 2007

Znaleziono wyników: 1

Liczba wyników na stronie

Wyniki wyszukiwania

Sortuj według:

Ogranicz wyniki do:

Improved saponification then mild base and acid-catalyzed methylation is a useful method for quantifying fatty acids, with special emphasis on conjugated dienes

Czauderna M., Kowalczyk J., Korniluk K., Wąsowska I.

Acta Chromatographica

2007

No. 18

59-71

The objective of this study was to evaluate mild lipid saponification then gentle base and acid-catalyzed methylation, in succession, at 80°C, 60°C, 40°C, or ambient temperature for quantification of fatty acids (FAs), with special emphasis on conjugated linoleic acid (CLA) isomers. Methylation at 80°C resulted in a substantial increase in the amount of trans,trans (t,t) CLA isomers and in loss of cis,trans/trans,cis CLA isomers, as a result of intra-isomerization and formation of artefacts. Methylation at 40°C, in contrast, seems to enable the most accurate quantification of CLA isomers, because it resulted in no noticeable intra-isomerization of conjugated dienes or formation of artefacts. Under these derivatization conditions, other FA methyl esters (FAMEs) also seem to be accurately quantified. The proposed procedure adequately prepares FAMEs from FA standards and from lipids in biological samples, because mild saponification and methylation at 40°C using typical basic and acidic catalysts and subsequent extraction with a smaller volume of heptane resulted in satisfactory accuracy of quantification, negligible changes in the composition of FAs, especially conjugated dienes, and a better yield of FAMEs. The proposed improved procedure, comprising mild lipid saponification and methylation at 40°C in solutions carefully flushed with argon (Ar) (derivatization–Ar), in the absence of 2,6-di-tert-butyl-p-cresol, then extraction with 4 mL heptane, seemed the most satisfactory method of preparing FAs, particularly CLA isomers, for chromatographic quantification by argentation–liquid chromatography, the method of choice for analysis of fatty acids containing conjugated double bonds.