How would you test if a supplement truly contains what it says it contains?

[EasyEJL]

I've found a source of resveratrol that is ridiculously cheap, $1/g of active, capped. How would I go about actually getting a few caps tested?

 

[BigAsTheSky]

Gcms

Give a sample to PA and have him put it thru the chromiograph.

 

[Vitruvian]

Easy, a simple first step to check legitimacy is see if someone with many a source will divulge the going rate that they get it at. If someone like Dirk or Dsade can't get it that low..... you can guess it's probably bootleg. lol