The answer is "no" unless you take a specific bottle to be tested by an independent lab. Then you'd need to do the same with the very next bottle you purchase (even if it's the same brand). And so on.
I am including 3 links to articles about the problems with putting hope + faith in scientifically unproven, unregulated supplements like CBD oil. Please make sure you speak with your physician before adding it to your diet so they can be aware of any interaction with any other medications you are taking.
FYI people are failing drug tests because not all of the THC is completely removed by the manufacturers! Also, dosages can vary from what the labels indicate. The CBD industry has been called the "Wild West" as tens of thousands of suppliers and sellers jump into the very lucrative fray. It's bad enough that numerous Attorneys General are lobbying for it to be regulated by the FDA.