Astaxanthin isomers were analyzed using
normal-phase HPLC with a photodiode array detector (SPD-M20A; Shimadzu,
Kyoto, Japan) as previously described.18 (link) Briefly, two silica gel columns connected in tandem (Luna 5 μm
Silica (2), 2 mm × 150 mm × 4.6 mm, 100 Å, Phenomenex
Inc., Torrance, CA) were used as the stationary phase, and a mixture
of hexane, ethyl acetate, and acetone (70:20:10, v/v/v) was used as
the mobile phase. The column temperature was adjusted to 40 °C,
and the flow rate was maintained at 1.2 mL/min. The quantification
of astaxanthin isomers was carried out by peak area integration at
470 nm. The peaks of astaxanthin E/Z-isomers in the chromatograms were identified by retention times
and spectral data (i.e., whole band shapes of the absorption spectra,
maximum absorption wavelengths, and relative intensities of the Z-peak to the absorption maximum peak of the isomer [Q-ratios]).12 (link),14 (link),18 (link),19 (link) The total (or each) Z-isomer
ratio of astaxanthin was determined as follows
normal-phase HPLC with a photodiode array detector (SPD-M20A; Shimadzu,
Kyoto, Japan) as previously described.18 (link) Briefly, two silica gel columns connected in tandem (Luna 5 μm
Silica (2), 2 mm × 150 mm × 4.6 mm, 100 Å, Phenomenex
Inc., Torrance, CA) were used as the stationary phase, and a mixture
of hexane, ethyl acetate, and acetone (70:20:10, v/v/v) was used as
the mobile phase. The column temperature was adjusted to 40 °C,
and the flow rate was maintained at 1.2 mL/min. The quantification
of astaxanthin isomers was carried out by peak area integration at
470 nm. The peaks of astaxanthin E/Z-isomers in the chromatograms were identified by retention times
and spectral data (i.e., whole band shapes of the absorption spectra,
maximum absorption wavelengths, and relative intensities of the Z-peak to the absorption maximum peak of the isomer [Q-ratios]).12 (link),14 (link),18 (link),19 (link) The total (or each) Z-isomer
ratio of astaxanthin was determined as follows
Free full text: Click here
