SOP For Procedure for Preparation, Standardization and usage of Working Standard.

The purpose of this SOP is to define the procedure for preparation, standardization and usage of working standard.

This SOP is applicable to Quality Control Department at manufacturing facility of Pharmaceutical Industry.    



            Use clean and dry amber colored vials for storage of working standards.

Store all Reference standards / impurity standards as per the storage condition mentioned in respective MSDS from supplier.

            Before use, the temperature of vials should reach the room temperature.

In case potency of working standard is found to be more than 100.0% on as is basis during the standardization, as a policy cut-off the potency of working standard shall be considered as 100.0%.

Maintenance of Reference Standard:

Reference substances or Reference standards are authentic purified chemicals or substances supplied by the official pharmacopoeial commissions. These are used for comparison for determining the purity of the test specimen.

In case reference standard is not available in any of the pharmacopoeial catalog, manufacturer shall be requested for their reference standards / working standards with certificate of analysis.

As Reference Standards are available only in small quantities, working standards shall be prepared to act as substitutes. These shall be prepared from approved raw material and validated against authentic Reference standards or Reference substances. Standardizations records of Working Standards shall maintained in Q. C. laboratory.

Inventory and consumption of Reference standards shall be maintained as per Annexure – VI.

List of available Reference Standards shall be prepared as per Annexure – VII.

Validity of Reference standards shall be verified by quarterly basis and            before use for preparation of working standard.

Verification of Reference standard shall be done with following websites


In case the Reference standard are found to be consumed /expired during verification, the indent for procurement of fresh lot shall be initiated by       Manager QC.

Working Standards Preparation:

Select any approved batch. The quality attributes of selected batch shall be reviewed critically with special emphasis on its assay and related substances. The selected batch shall have maximum Assay / Purity and lowest Related Substances.

Analyze the selected batch against the reference standard. Record the details in Reference standards usage logbook as per Annexure – VI.

Selected batch shall be analyzed for the following test as per the stipulated control procedure.



Moisture content (Water by Kf / Loss on Drying)


Perform assay and moisture content analysis in triplicate.

The % RSD of three values for a set of assay shall be calculated. The % RSD should not be more for than 2 % for HPLC /GC assay, 1% for chemical Assay and 5% for Microbiological Assay.

While preparing working standards intended use shall be considered. eg. Sucrose is used for IR comparison hence IR shall be compared for qualifying sucrose working standard against Sucrose CRS/RS

Certificate of Analysis for working standard shall be prepared as Annexure – III.

Q. C. Manager shall allocate the material abbreviation and assign a unique number to each working standard. The procedure for numbering shall be as below.



WS – denotes the working standard

‘/ ‘- denotes the slash

XXXX – denotes the four letter abbreviation for the material 

YY – denotes the year of preparation of working standard

01 – denotes the serial number of working standard.              

A typical example of Paracetamol working standard shall be as below.


In case the working standard is prepared two times in a year due to change in lot number of pharmacopeial reference standard or any other reason the

01 number shall be changed to 02 and so on.

Enter the details of results in the Record of Analysis sheet & calculate the purity of working standard.

Transfer the working standard in clean amber colored vials, seal them, and label them as per Annexure – V.

Fifteen vials each of 2 gm should be prepared and another 20 gm Working Standard should be stored in vial.

In case of most consumable working standards, prepare fifteen vials each 15 gm and another one vial of 20 gm.

Prepare a list of working standard to identify the due date for preparation of working standard as per Annexure – IV.

In case of absence of API or CRS (BP/EP/USP) working standards received from manufacturer shall be used for respective analysis.

Storage of working standards

Store all working standards under refrigeration; In case any specific storage condition is mentioned for a particular material then that material shall be stored according to its specific storage condition.

All working standard shall be brought to ambient temperature before use.

Record the details of usage of working standards in usage logbook as per Annexure-I

  • Expiry:

Expiry period for working standards is one year from the day of preparation.

Expiry period of vial is one month

Expiry period of working standard should not exceed than retest period of selected API batch.

  • Disposal:

Expired working Standards / Reference standards should not be used and should be disposed immediately.

Record of disposal shall be maintained in working standards/Reference standards usage logbook.


As per Employee Training


As per SOP of SOP


Annexure I      : Working standard usage log book

Annexure II    : Working standard qualification attributes

Annexure III   : Working standard certificate of analysis

Annexure IV   : List of working standard.

Annexure V    : Label for working standard vials

Annexure VI   : Reference standard usage log book

Annexure VII : List of reference standard

Note:- This SOP is Strictly Applicable for EU/USFDA Approved Plants

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