ABSTRACT
The reproducibility of the separation of astaxanthin stereoisomers on columns packed with Pirkle covalent L-leucine chiral stationary phase (CSP) was examined by comparing six columns purchased from the same manufacturer. Differences were found even for columns packed with CSP from the same lot. The reproducibility of columns packed with Pirkle covalent D-phenylglycine CSP was also examined by comparing columns purchased from the same manufacturer as well as from different manufacturers. Significant differences were found for columns packed by different manufacturers. Chiral column-to-column reproducibility for complex stereoisomeric separations should therefore not be taken for granted.
Subject(s)
Glycine/analogs & derivatives , Leucine/chemistry , beta Carotene/analogs & derivatives , Chromatography, High Pressure Liquid , Glycine/chemistry , Reproducibility of Results , Spectrophotometry, Ultraviolet , Stereoisomerism , Xanthophylls , beta Carotene/chemistry , beta Carotene/isolation & purificationABSTRACT
Analytical methods are needed to determine the presence of color additives in fish. We report a liquid chromatographic (LC) method developed to identify the synthetic form of the color additive astaxanthin in salmon, based on differences in the relative ratios of the configurational isomers of astaxanthin. The distributions of configurational isomers of astaxanthin in the flesh of wild Atlantic and wild Pacific salmon are similar, but significantly different from that in aquacultured salmon. Astaxanthin is extracted from the flesh of salmon, passed through a silica gel Sep-Pak cartridge, and analyzed directly by LC on a Pirkle covalent L-leucine column. No derivatization of the astaxanthin is required-an important advantage of our approach, which is a modification of our previously described method. This method can be used to distinguish between aquacultured and wild salmon. The method has general applicability and can also be used to identify astaxanthins derived from other sources such as Phaffia yeast and Haematococcus pluvialis algae.
Subject(s)
Aquaculture , Chromatography, Liquid , Food Additives/analysis , Oncorhynchus keta/metabolism , Salmon/metabolism , beta Carotene/analogs & derivatives , Animal Feed , Animals , Animals, Wild/metabolism , Color , Female , Food Analysis , Male , Molecular Structure , Stereoisomerism , Time Factors , Xanthophylls , beta Carotene/analysisABSTRACT
We report an HPLC method that allows the simultaneous separation of configurational isomers of the predominant cis/trans forms of astaxanthin. The configurational isomers of the all-trans-, and most of the configurational isomers of the 9-cis-, 13-cis- and 15-cis-astaxanthin were separated on a Sumichiral OA-2000 column, which is manufactured and packed in Japan with a Pirkle covalent D-phenylglycine chiral stationary phase (CSP). The large separation of the cis isomers from the all-trans isomers that we report here ensure the suitability of this method for the routine determination of the ratio of the configurational isomers of all-trans-astaxanthin.
