Expired working standards for R&d trials analysis

Dear all, we in our company during the process of development of new product ,API of this product has been expired ,and as it is single batch of API present in our warehouse and formulation team continue to use it for their R&D trials till new batch of API arrive(MAY take more than year ),through this period i have no valid working standard, i have to use this expired API as working standard for R&D trials analysis.

  • i don’t have valid reference Std from official or vendor of API…to standardize the expired API.
  • All API stored in their labelled storage condition according to pharmacopoeia or Vendor.
  • Can i use this expired standard and labeling it as “For R&D Trials only” which indicate that those standards for R&D trials analysis only not for routine analysis??
    and i have to write the expired data on this vials or leave it blank to be indication of its expiration or accepted to write " till new std arrive"???
  • is it accepted for audit to add this standards to My SOP of working standard with precaution i add as “For R&D Trials only” labels and “till new std arrive” labels and has different label colors than other valid standards???