Question about having the quality of a Chinese product tested?

Hello all!

I'm considering looking into making bulk purchases, preferably directly from the manufacturer, though possibly from a trading company, likely through Alibaba etc. ie. Likely of Chinese origin.

Suppose the product I'm looking for is a supplement or vitamin.

I'm looking to learn how and where one would "go" in order to have the following sorts of things tested: – authenticity, "is it what it should be?" – quality/ purity (Do these two terms mean the same thing?) "What percentage of impurities are present in the product, AND what ARE those impurities? ie. Toxic heavy metals vs …? – "Anything else?"

I'm sure that 'a laboratory' is the answer. 😉 But I do have two further questions.

1. How does one locate such reputable laboratories that offer these tests to the public?

Many sellers provide Quality Control documents; but those are obviously easily doctored.

1. Is there any consensus regarding whether it would be best to have the product sent to a lab in China prior to having the product sent to me (if the testing went well), or should the product be tested here in Canada or America etc?

Thanks guys. 🙂