The most quantitative method will be to extract the axtaxanthin and use an analytic chemistry technique such as GC/MS.

However astaxanthin is a photo pigment like other carotenoids, thus there will be well defined asborbance peaks for astaxanthin that can be measured on intact cells to monitor the astaxanthin production in vivo as you wish.

I suggest a pubmed search on astaxanthin, asborbance, in vivo, Haematococcus and you should find some papers with methods.

Hope this helps

Yes, it could be assayed via optical density of the Haematococcus cells deposited on a glass-fiber filter such as Whatman GF/F. One needs to obtain a calibration vs. content of the pigment measured analytically first. Sorry, I do not have the reference at the moment (the paper is under review). The technique of the filter-based measurements is described here (see attachment).

This is the file.

Hi, actually, it really depends on what you are searching. Do you need to have a quantitative assays or relative data. You can always measure the change in the absorbance spectrum of the intact algae. You will be able to differenciate the ketocarotenoids (it means that you wiull not be able to differenciate astaxanthin from cantaxanthin for instance) from the other carotene because they have typical absorbance spectra. Otherwise, you can use TLC or HPLC (see the attached files). If you are interested by some papers, please send me your e-mail at [email protected]

Best.

Benoît