Expiration of Secondary 'Daughter' Standards

Ron writes...
We're having an internal debate over this question: Do secondary (daughter) standards expire at the same time as the primary (parent) standards from which they were made? What is the logic behind the arguments? We have many examples where a daughter was made, but was not "expired" or totally consumed before the parent expired.

Dear Ron,

It is the policy at Inorganic Ventures that the 'daughter' expires one year from the date of preparation, assuming that the following conditions are met (at a bare minimum):

  1. The standard is chemically stable for a minimum of 24 months and preferentially for several years.
  2. That physical stability is limited to only transpiration instability.
  3. The parent standard (specific to lot #) has exhibited 0 questionable 'offspring' and/or investigations have proven it to be intact.
  4. The parent has been stored under conditions that meet conditions specified by manufacturer and that have been documented.
  5. There are no non-conformities (in general), i.e., there have been no opened investigations into preparations of this chemical/standard under the same or similar chemical and physical conditions.
  6. There are no internal company or regulatory restrictions to the expiration date of this chemical standard or to 'offspring' in general.
  7. The laboratory and/or quality control manager(s) are aware of policy/practices and are in agreement with such.

For more information, please take a look at our Tech Center articles pertaining to expiration date. Thank you for your question.

Serving you in chemistry,

Paul R. Gaines, Ph.D.
CEO of Inorganic Ventures & Fellow Chemist

DISCLAIMER: Advice offered by the chemists at Inorganic Ventures is intended for the individual posing the question. Feel free to contact us to verify whether these suggestions apply to your unique circumstances.