Extending Shelf Life for Dietary Ingredients

Hello, 

We manufacuture dietary supplements and one of our amino acids does not have an expiration date listed on the CoA.  We send the product off for retest for purity , micros, metals etc. and everything came back still over 98 percent pure and within spec.  How long can we extend shelf life and how would we accomplish this?

Have you asked the supplier of the amino acid? Even if they won't give their own formal extension, they're normally best-placed to advise on what the limiting factors are for the life, what tests would be appropriate for determining ongoing suitability for use, potential extension period before further retests etc.