Yes, volumetric solutions should be standardized before use and re-standardized periodically.
The frequency of re-standardization should be defined based on the stability of the solution, its intended use, and frequency of use.
FACT: A standard's expiration date and shelf life are two entirely different entities.
Chemical stability is only one of many factors involved in defining expiration date and shelf life.
However, for in-house prepared solutions used for quantitative analysis, such as sample or standard solutions used in assay or impurity testing or titration solutions, FDA requires that formal stability studies be conducted to determine an appropriate expiry.
As mentioned in The determined "use by" or expiry dates should be documented within a procedure and followed.
The FDA expects an assessment to be performed for purchased laboratory reagents without expiry date indicated by the manufacturer.
This information will help you make the correct decisions when other suppliers throw misleading comments into the mix.Inorganic Ventures can state with certainty that there are no chemical stability problems that have not been solved.Number 1 above has been eliminated in our facility.For in-house prepared solutions (like as mobile phases or other non-quantitative solutions), the FDA expects an assessment to be carried out, too.However, the FDA requires formal stability studies to be performed to determine an appropriate expiry for in-house prepared solutions used for quantitative analysis in assay or impurity testing.