A quality plan can help

Answer:
I don’t know the purpose of that sampling that you made, but if I collected samples from a supplier and gave them for testing, I would want to keep a sample with me, a kind of “sample testimony”. Later, if you are suspicious of any thing you can take that testimony and request further testing by your team or a third party.

To prevent any future problem, I advise you to create or update your quality plan. The following material will provide you information about quality plans:
- ISO 9001 – Making the best out of ISO 9001 Quality Plan - https://advisera.com/9001academy/blog/2015/12/08/making-the-best-out-of-iso-9001-quality-plan/
- free online training ISO 9001:2015 Foundations Course - https://advisera.com/training/iso-9001-foundations-course/
- book - Discover ISO 9 001:2015 Through Practical Examples - https://advisera.com/books/discover-iso-9001-2015-through-practical-examples/