hplc for lycopene

[wolfgangmoritz]

hello everyone

we are trying to set up a hplc for lycopene in tomato

right now we still have a few problems:

- where do I get a good standard - we have experienced badly soluble ones with low contents.
- does someone know a reliable laboratory anywhere that does good analyses, so that we can have some reference-analyses done
- or even: are there ring-test for lycopene around??

Thank you for any idea,

wolfgang

[Mark Tracy]

I got some from LycoRed (www.lycored.com) that was pretty good. I liked the Lyco-Pen 2 SG which is 2% crystalline lycopene suspension in glycerol.

[wolfgangmoritz]

Hello Mark

Does Lycored supply a good certificate of analysis. If I would use a photometric assay to quantify Lycopene prior to HPLC, in this product other components would interfer with the determination?

W.

[Mark Tracy]

They can provide a COA on request, assayed by spectrophotometry. I found a few percent of cis isomer by HPLC, easily recognized by its spectrum. No carotene in the sample I got. (Actually a colleague obtained it and shared it with me.)

It is challenging to weigh and dissolve it given that lycopene is soluble mainly in hydrocarbons and glycerol is mainly soluble in water.

[wolfgangmoritz]

Today I have been speaking with some other person that does carotinoid-analyses. They have disuaded me from standards that are not 100% pure. I think I will have to "bite into the sour apple" as they say in Germany, and buy the expensive pure standard from eg. Fluka.
About a laboratory that could check our results, I have not got very further, especially as the product and extraction have to match closely, so the results from outside will not be necessarily better.

W.