SOP FOR CALIBRATION OF ANALYTICAL BALANCE .

1.0       OBJECTIVE:

To provide guideline for operation and calibration of Balance.

2.0     SCOPE:This SOP covers operation and calibration of Analytical balance 

3.0    RESPONSIBILITY: QC Officer: Responsible for operation, daily calibration and maintenance of the balance as per procedure.
         QC Manager/QC Executive: Review the records and governing the document.

4.0     PROCEDURE:

4.1  CLEANING OPERATION:

4.1.1           Wipe all the traces of organic solvent/water by tissue paper.

4.1.2           After weighing clean the pan with cleaning brush

4.1.3           Clean all the dust from the pan by tissue paper or using a cloth which has been wet   with mild detergent (Soap).

4.1.4           Make sure that no liquid enters the balance/scale housing.

4.2                 OPERATION:

4.2.1           Ensure the instrument is clean and free from dust.

4.2.2           Prior to start the work clean the pan properly with 70% v/v IPA solution.

4.2.3         Set the spirit level in middle position with adjustment of balancing screws  provided below.

4.2.4           Switch ON the main power supply.

4.2.5           Press POWER key to ON/OFF the balance.

4.2.6           Balance will perform autocalibration.

4.2.7           Press ←O/T→ key to get zeros on the display, 0.0000 g.

4.3                 SAMPLE WEIGHING PROCEDURE  

4.3.1           Place butter paper/container on the weighing pan, after the stability mark (g) is lit     and press the TARE key.

4.3.2           Load the sample when the stability mark (g) is lit and display shows 0.0000 g.

4.3.3           Close the door of outer cover, wait until the constant value appears on display.

4.3.4           Read off the weight indicated on the display only after the weight unit “g” or a  different unit selected appears as the stability symbol.

4.3.5           Remove the sample and close the door of outer cover.

4.3.6                 Switch off the balance at the end of day’s operation. 

4.4                 CALIBRATION PROCEDURE

4.4.1        Daily Calibration :

4.4.1.1        Switch on the instrument, instrument initialize itself for auto calibration. Observe  the  display and record the same. (Refer Annexure-I).

4.4.1.2        For daily calibration, press ←O/T→ key to read zero on display.

4.4.1.3        Place standard weight 10.0 mg by using forcep on the weighing pan.

4.4.1.4        Close the door of outer cover, wait until the constant value appears on display.  Repeat the same with standard calibrated weight 50.0 mg, 200.0 mg, 1.0 gm, 10.0 gm, 50.0 gm, 200.0 gm & record the details. (Refer Annexure-I).

4.4.1.5        Also note down the details in instrument log book. (Refer Annexure-II).

4.4.1.6        The observed weights shall be within ± 0.1 % of the calibrated weight.

4.4.1.7        For weight box calibrated once in a year by external agency. [± 15 days].   

4.4.2           Monthly Check : Precision :

4.4.2.1        Place 500 mg, 1 gm, 100 gm calibrated standard weights separately on the pan at the center six times and record the weights observed in the monthly calibration format, as given in Annexure - III.

4.4.2.2        Then calculate mean and standard deviation.

4.4.2.3        Now calculate precision check by using the following formula.

                                    PC       =               3 X SD       

                                                            Mean weight

4.4.2.4        The precision check should not be more than 0.001 for any set of measurements.

4.5              CALIBRATION FREQUENCY:

   Calibration of Balance       : Daily

   Precision                           : Monthly

   Calibration of Weight-box : Yearly

                                                                                                                                                        

5.0          ANNEXURE(S):

             Annexure – I  -  Daily calibration record  

             Annexure –II  - Instrument usage log book

             Annexure –III - Precision check 

6.0           REVISION HISTORY:

             

Sr. No.	Revision No.	Change Control Number	Details of Revision	Reasons(s) for Revision

Anaxeture 1  

Instrument                    : Balance                                 Instrument ID                    :

Month & Year              :                                              Make & Model                   :

Calibration Frequency :  Daily                                   Weight box Reference No. : 

Nominal Value	Actual weight	Tolerance (± 0.1 %)
		Minimum	Maximum	± in
10.0 mg
50.0mg
200.0mg
1.0 gm
10.0 gm
50.0gm
200.0gm

Date	Auto Calibration	Nominal Value	Actual weight	Observed Weight	Difference	Calibrated by	Remark	Checked by
		10.0 mg
		50.0mg
		200.0mg
		1.0 gm
		10.0 gm
		50.0gm
		200.0gm

Anaxeture II

Sr. No.	Date	Name of the sample/detail	Batch no.	A.r. No	Test performed	Time	Sign	Checked by	Remark

Anaxeture III

Nominal Value(Actual Weight)	500.0mg (499.93 mg)	1.00 gm (1.00012 gm)	100.0 gm  (99.99720 gm)
1
2
3
4
5
6
Mean Weight
SD
PC (Lt. : 0.001)
Calculation Formula :  PC       =           3 X SD__                                                                    Mean weight
Calibration Status : Satisfactory / Not Satisfactory
Calibrated by :                                                                                  Checked by :