Where can I have a product's materials tested?

Sorry if this is the wrong sub for this question. I purchased a product, as a consumer, and suspect it may contain materials that were not advertised. What kind of lab can I send it to in order to determine this? When I search material testing, the labs all seem to cater specifically to manufacturers, not individual consumers.

If there's a different sub I should visit to ask this question, I would appreciate the guidance. Thank you!