Standard Operating Procedure For Correct Weighing In Pharmaceutical Quality Control

1.0                                     OBJECTIVE

1.1                   To lay down the procedure for the correct weighing technique.

2.0                    SCOPE

2.1                   This procedure applies to Quality Control laboratory 

3.0                    RESPONSIBILITY

3.1                                     Chemist- Quality Control responsible for the correct weighing during analysis.

3.2                   Head - Quality control or designee responsible for compliance of the SOP.

4.0                    PROCEDURE

4.1                  Ensure that the balance is clean and check the spirit level, if spirit level is   not aligned, adjust the same with the knob provided.

4.2                   Check the condition of silica, if it has turned pink / colourless then replace with                                  fresh silica.

4.3                 Check the calibration tag on balance for the validity. If not valid, then get the                             calibration done as per respective balance SOP, then only proceed for weighing.

4.4                   Check whether internal calibration of balance is done, if not then get it done,                            record it and then only proceed for weighing.

4.5                   Weighing of Solid material:

4.5.1                Use appropriate size of butter paper with respect to the quantity of the sample to be           weighed.

4.5.2                                 Place the butter paper on the pan of the balance and tare the weight to zero.

4.5.3                Place the desired quantity of the sample slowly at the centre of butter paper using a clean spatula. The weight taken should be within ± 10 % of the specified weight.

4.5.4                Close the door of balance and note down the weight of sample.

4.5.5                Carefully transfer the contents from the butter paper to the desired container (eg. Conical / Volumetric flask) ensuring no spillage of the powder.

4.5.6                      After completion of the transfer, place the butter paper back on the pan of balance.          Shut the door of balance, note down the weight and balance code No. in record of                    analysis. The weight of the sample is the difference in the two weights.

4.5.7                After completion of weighing, the usage details shall be entered in log book of the respective balance.

4.6                   For weighing of Liquid samples

4.6.1                  Check the outer edge and bottom of the container (e.g. Volumetric/ Conical flask /                            Beaker) into which the liquid sample has to be weighed. It should be clean and dry.

4.6.2                  Place the container on the pan of the balance. Ensure that the total weight of the   container              and the weight of the sample required does not exceed the capacity of the balance.

4.6.3                Tare the weight of the container to zero.

4.6.4                If the sample to be weighed is volatile it is advisable to put little diluent in the                                           container, (whenever the sample is required to be diluted) tare the weight and then     weigh                        the sample.

4.6.5                With the help of a clean and dry pipette transfer desired quantity of the liquid sample                                   to be weighed into the container.

4.6.6                  Close the door of balance and note down the weight of the liquid (It should be within          ±           10 % of the specified weight) and the balance code no. on the record of analysis.

4.6.7                  After completion of weighing, the usage details shall be entered in log book of the respective balance.

                        Note: After completion of weighment, clean the balance and the surrounding area.