Where I can find a reliable allicin standard for HPLC analysis? Can somebody help me?

Allicin is a very unstable compound that very rapidly degrades to other compounds. Given that, I would think that standards for allicin are hard to come by. You may be able to estimate allicin content by comparing it to the more stable Alliin, which is available from a company called Indofine (and others). Check this reference for information on the degradation products.

Amagase, H., Petesch, B., Matsuura, H., Kasuga, S. and Itakura, Y. Intake of garlic and its bioactive components. J. Nutr. 131(3S): 955S-962S, 2001.

Hello,
there is one source I know, where you can get reference standards in high quality, together with a complete documentation, including HPLC methode.
Here is the address and contact person:
Phytochem
Mr. Hans Rausch
Reutierstrasse 56
89231 Neu-Ulm
Phone:+49-(0)731-97205-45
Fax: +49-(0)731-97205-46
e-mail:phytochem@t-online.de
They have also a partner in the USA, so far I know.
Hope this helps.
Gerhard

I know another very good source to purchase natural products reference standards together with a very good documentation (also on CD). All methods used characterisation of compounds are described. But, as far as I know, they do not have allicin in stock for the reasons stated above. However, you might want to contact them. Here 's the adress:

ZA GmbH
Zentralinstitut Arzneimittelforschung GmbH
attn. Dr. Sven-Oliver Kruse
Kranzweiherweg 10
D-53489 Sinzig
Phone: +49-2642-9837-30
Fax: +49-2642-9837-40
e-mail: za@za-sinzig.de
web: www.za-sinzig.de (just hit the flag in the upper left area to reach the english homepage)

Again, just like Gerhard Kratz I hope this helps...
Frank