SOP for Reference Standard Control

To provide a procedure for controlling and storage of reference standards. 

This procedure shall apply to all the reference standards that are used for analysis.

  • It is the responsibility of the QC Executives for ensuring that the standards are used appropriately, stored in the right conditions. 
  • It is the responsibility of the QC Manager to ensure that all standard prepared & qualified against reference standard & documented. 

Classification of Reference Standard:
  • Primary Standards: These have been prepared and classified as such by competent accredited bodies such as USP, BP, FDA, WHO. Unless otherwise stated primary standards are taken as being 100% pure. 
  • Secondary Standards: This is prepared from a selected batch of an active ingredient after it has been tested against a Primary Standard and has passed all monograph requirements. 
Classification of Secondary Reference Standards:
  1. Selection of Sample, Sample quantity & sampling of Raw material 
  • Select the latest approved batch of Raw material preferably having maximum assay. 
  • Sampling quantity shall be calculated on the basis of the sample required for analysis and preparation of secondary reference standard. 
  • Perform the sampling as per current SOP of sampling of secondary reference standard 
  2. Analysis of material: 
  • Carry out the following test for preparation of secondary reference standard 
          Loss on drying/Water content 
          I.R. (Where applicable) 

          * Assay shall be done in Triplicate 
  • Enter the results in the data sheet for secondary reference standard of the respective material. Secondary reference standard data sheet shall be prepared as per Attachment-I 
  • Calculate the average of three assay values obtained on as is basis.
  • The RSD of three assay values obtained on as is basis should not be more than 1.0% for chemical assay and 5.0% for microbial assay.
  • When approved the following should be entered on the Certificate of Analysis for Secondary Standards: 
        a. Name of Secondary standard. 
        b. Date of certification. 
        c. Expiry date. 
        d. Assay (as such). 
        e. Loss on drying/ Water content 
        f. Analyst’s signature and date. 
        g. Approval signature and date. 

 3. Preparation & labelling of vials 
  • Prepare the List of secondary reference standard as per Attachment-II (List of Secondary reference standard). Assign the reference number to Secondary Reference Standard as follows. Number the Secondary Reference Standard as 
            SRS : Secondary Reference Standard, 
            XXX : Corresponds to the serial no starting from 001. 
            YY: Corresponds to the last two digit of year in which secondary 
                  reference standard prepared. 
            BB: Corresponds to the no. of vial prepared for particular 
               secondary reference standard starting from 01.e.g. 
               SRS/001/20-01, where SRS – Secondary Reference Standard, 
001 is the reference no for – Ibuprofen, 20 describes the secondary reference standard prepared in year 2020, 01 – First secondary reference standard in series in the year 2020. The second secondary reference standard of Ibuprofen prepared in the year 2020 shall be numbered as SRS/001/20-02 
  • Store the material in light resistant glass vials closed with cap. 
  • Label the vials with the following details. 
       a. Name of Secondary Reference standard 
       b. Ref. No. 
       c. Assay (On as such basis) 
       d. LOD/Water content 
       e. Date of preparation 
       f. Use before 
  • Assign one-year shelf life for secondary reference standard when expiry of sample used for secondary reference standard preparation is more than one year 
  • If the secondary reference standard is not qualified in-house and is supplied by an external party, the results from the certificate of analysis shall be adopted and recorded on the secondary reference standard analytical report. A reference standard number is assigned to such reference standard and recorded. 
  4. Storage and handling of reference standards: 
  • Store all secondary reference standard in A.C control area (below 27°C)/ refrigerator (Between 2 to 8°C). Keep the vials air tight protected from heat, moisture and light. Primary Standards should be stored in their original stoppered containers. 
  • Moisture sensitive Reference Standards must be stored in desiccators. 
  • Unless otherwise directed, Reference Standard must be dried before use as directed in their labeling or in the monograph. 
  • Reference Standards will be used in the assay of certain raw material or finished dosage forms, or to determine a specific impurity in either. 
 5. Precaution: 
  • Analyst shall check the expiry of secondary reference standard before use. 
  • The analyst shall keep the standard out of the recommended storage for as short as possible to protect from light and moisture.
  • Equilibrate secondary reference standard to room temperature before use, which are stored in refrigerator. 
  • Use required quantity and do not put back the secondary reference standard in vial.
  • Ensure proper closing of the vial after use. 

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