The certified standard is very much important in pharmaceutical analysis. It ensures that the performed analysis is accurate and assure the safety of drug product. The analysis is always carried out by using the working standard and results are reported against the working standard.
Working standard is defined as, “A drug substance of established quality and purity as shown by comparison to the reference standards.” This working standard is used for routine analysis.
The working standard is qualified against the pharmacopeial reference standard or certified reference standard. Qualification of a working standard is done by using a verified or validated analytical method and its results are compared with the reference standard.
Primary Standard, Reference Standard, or Pharmacopeial Standards is well characterized and certified material by standard regulatory agencies or appropriate laboratories. These reference standards are available with minimum pack quantity at a high cost. Due to the higher cost of the primary reference standard, it is not possible to use this standard for routine analysis. Due to this reason, the working standard is prepared for routine analysis. bearing reference to the original certified reference material.
The working standard must be high purity grade materials. Following is the selection criteria of the drug substance batch for the working standard preparation.
Assign the purity on an as-is basis and also need to check if there is any salt and base correction factor required. Also, it must have clear instructions on vial about use purity on an as-is basis or dry the standard before use with clear temperature condition or depending on the pharmacopeial monograph or as per primary standard test procedure.
After analysis assigns the validity depending upon the nature and stability of drug substance. The validity of the working standard shall be assigned for 1 year or it must be within the retest date or expiry date of drug substance assigned by the manufacturer.
After completion of the analysis and report generated, prepare the COA, and submit for the QA review along with a hard copy or electronic data.
After approval of report label the working standards bottles properly with following details:
Store the working standard as per the storage condition of the drug substance. The validity of working standards shall be one year or depend on the nature and stability of the compound. Working standard shall be stored in amber-colored glass bottles with airtight closures. Each vial shall be used for maximum of 2 months or depending on the nature of the standard.
One vial with an adequate quantity of the working standard shall be kept as a “Control sample”.
The working standards shall be revalidated at well-defined intervals to ensure its purity, integrity, and authenticity. Maintain the usage record of the working standard.