STANDARD OPERATING PROCEDURE Operation and Calibration of Analytical Balance

	STANDARD OPERATING PROCEDURE
	Department: Quality Control	SOP No.: QC/MB/
Operation  and Calibration of Analytical Balance		Effective Date:
		Review Date:
		Page No.:

1.0                                   OBJECTIVE:

1.1                            To lay down a procedure for Operation, Calibration and cleaning for Analytical Balance.

2.0            SCOPE:

2.1                            This procedure is applicable to Analytical Balance located in microbiology laboratory at Pharma Private Limited.

     ID No.

     Make: Mettler Toledo

     Model No.:

Minimum weight: 0.2 g,

     Maximum weight: 120 g,

     ‘d’ value: 1mg

     Operational Range: 820 mg to 100 g

3.0                            RESPONSIBILITY:

3.1                 Microbiologist: Responsible for operation of instrument.

3.2                 Section In-charge: Responsible for review the procedure

3.3                 QC Head: Responsible for implementing the procedure.

3.4                 QA Head: Overall compliance.

4.0            PROCEDURE:

4.1                 Precautions during measurement:

4.1.1                      Do not use any organic solvents to clean the balance. (Ensure cleaning solution is not directly used).

4.1.2                      Do not allow the material to remain on the balance for an extended period of time.

4.1.3                      The total weight on the pan of the balance should not exceed the operating range.

4.1.4                      In case of any defect immediately unplug the instrument from mains.

4.2                 Cleaning Procedure:

4.2.1                      Clean the balance with nylon brush or lint free cloth.

4.2.2                      Wipe down draft shield doors, weigh pan and exterior with lint free cloth which is soaked in mild detergent or approved disinfectant.

4.3                 Operating procedure:

4.3.1                      Ensure that the balance is clean and free from dust.

4.3.2                      Ensure balance is on a solid, level surface, away from drafts and sources of vibration.

4.3.3                      Use adjustable feet to adjust bubble level which is located at the front of the unit to ensure the balance is level prior to use.

4.3.4                      Plug in unit (if necessary) and press the  key. Balance should be allowed to “warm up” for at least 45 minutes prior to use. (To enable the balance to adapt itself to the ambient conditions).

4.3.5                      Long press   key, the balance will show  followed by this indicates the balance is in standby mode.

4.3.6                      Then press and hold the   key then the display will show.

4.3.7                      Now the balance is ready to weighing.

4.3.8                      Press  key to convert the measurement unit in ‘mg’.

4.3.9                      Place the sample and note down the weight appears on display.

4.3.10                  After weighing transfer the sample and then press  key to tare it.

4.3.11                  After usage, long press key then display will show  followed by, this indicates the balance is in standby mode.

4.3.12                  Always keep the balance in standby mode only.

4.3.13                  If balance is in standby mode it is immediately ready for weighing (warm-up period is not required).

4.3.14                  Usage details of analytical balance shall be entered in Annexure – III.

4.4                 Calibration Procedure:

4.4.1                      Daily Calibration:

4.4.1.1                Internal Calibration (Auto Calibration):

4.4.1.1.1          Press and hold  key until  appears.

4.4.1.1.2          Then select by pressing key.

4.4.1.1.3          The display will show.

4.4.1.1.4          Then press  key to execute “internal adjustment”.

4.4.1.1.5          The balance adjust itself automatically and finally the display will show  if the adjustment done properly.

4.4.1.1.6          Internal Calibration (Auto calibration) shall be done when ever needed.

4.4.1.2                External Calibration (Daily weight verification):

4.4.1.2.1          For weight verification, check the weights of 1g, 10g, 50g & 100g and records the observed weights in Annexure-I.

4.4.1.2.2          Weight verification shall be carried out at the starting of the day or whenever the weighing activity is carried out.

4.4.1.2.3          Acceptance criteria: Each individual value should not differ ± 0.1% of mass value.

4.4.2                      Periodic Calibration:

4.4.2.1                Sensitivity:

4.4.2.1.1          Definition: Change in weighing value divided by the change in load.

4.4.2.1.2          Place 100 g of the standard weight on the weighing pan, after the balance get stable record the observed weights in Annexure –II.

4.4.2.1.3          Calculate the sensitivity of the balance by using following formula

Sensitivity = ((Mass value – Observed value)/ Mass value) x 100

4.4.2.1.4          Acceptance Criteria: Should not be more than ±0.05%.

4.4.2.2                Linearity:

4.4.2.2.1          Definition: Ability of a balance to follow the linear relationship between a load and the indicated weighing value.

4.4.2.2.2          Linearity Level A: Place 1 g of the standard weight on the weighing pan, after the balance get stable record the observed weights in Annexure –II.

4.4.2.2.3          Linearity Level B: Place 10 g of the standard weight on the weighing pan and press the tare key, then place 1g of standard weight on the weighing pan after the balance get stable record the observed weights in Annexure –II.

4.4.2.2.4          Linearity Level C: Place 20 g of the standard weight on the weighing pan and press the tare key, then place 1g of standard weight on the weighing pan after the balance get stable record the observed weights in Annexure –II.

4.4.2.2.5          Linearity Level D: Place 50 g of the standard weight on the weighing pan and press the tare key, then place 1g of standard weight on the weighing pan after the balance get stable record the observed weights in Annexure –II.

4.4.2.2.6          Linearity Level E: Place 100 g of the standard weight on the weighing pan and press the tare key, then place 1g of standard weight on the weighing pan after the balance get stable record the observed weights in Annexure –II.

4.4.2.2.7          Calculate the linearity of the balance by using following formula

 Linearity = (Maximum difference/ Maximum capacity) x 100

Maximum difference is the maximum value which is obtained from B-A, C-A, D-A        and E-A.

4.4.2.2.8          Acceptance Criteria: Should not be more than ±0.05%.

4.4.2.3                Eccentricity:

4.4.2.3.1          Definition: The asymmetrical placement of the center of gravity of the load relative to the load receiver.

4.4.2.3.2          Place 50 g of the standard weight on center (C) of the weighing pan, after balance get stable record the observed weights in Annexure –II.

4.4.2.3.3          Same procedure is applied by placing the 50 g of the standard weight on Top (T), Bottom (B), Right (R) and Left (L) sides of the weighing pan individually.

4.4.2.3.4          Calculate the eccentricity of the balance by using following formula

Eccentricity = (Maximum difference/ Centre of mass value) x 100

4.4.2.3.5          Maximum difference is the maximum value which is obtained from C- T, C- B, C- R and C- L.

4.4.2.3.6          Acceptance Criteria: Should not be more than ±0.05%.

4.4.2.4                Repeatability:

4.4.2.4.1          Definition: Ability of a weighing balance to display identical measurement values for repeated weighing of the same objects under the same conditions.

4.4.2.4.2          Place 1 g of the standard weight on the weighing pan, after  the balance get stable record the observed weights in Annexure –II.

4.4.2.4.3          Repeat the same procedure for remaining nine measurements.

4.4.2.4.4          Calculate the repeatability of the balance by using following formula

Repeatability =        2X Standard Deviation____    X 100

                            Desired smallest net weight

Where A is the nominal net weight (Standard weight in mg).

4.4.2.4.5          If the standard deviation obtained is less than 0.41d (where d is the scale interval i.e.   1 mg), replace the standard deviation with 0.41d. Desired smallest net weight is 1g.

4.4.2.4.6          Acceptance criteria: Not more than 0.10%.

4.4.2.5                Accuracy:

4.4.2.5.1          Definition: The degree to which the result of a measurement, confirms to the correct value or a standard.

4.4.2.5.2          Place 20 g of the standard weight on the weighing pan, after balance get stable record the observed weight in Annexure –II.

4.4.2.5.3          Repeat the same procedure for remaining nine measurements.

4.4.2.5.4          Calculate the accuracy of the balance by using following formula

Accuracy = ((Mass value – Mean value)/ Mass value) x 100

4.4.2.5.5          Acceptance criteria: Not more than 0.10%.

4.4.2.6                Weighing Performance Test:

4.4.2.6.1          Definition: To check the performance of the balance throughout the range of the balance.

4.4.2.6.2          Place the respective standard weights (1g, 2g, 5g, 10g, 20g, 50g and 100g) on the weighing pan individually after balance get stable record the each observed weight in Annexure II.

4.4.2.6.3          Acceptance Criteria: Should not be more than ±0.10% of mass value.

4.4.2.7                Periodic Calibration frequency: Once in a month ± 3 days or after any major maintenance work.

4.4.3                      If analytical balance is failed to meet an acceptance criteria of calibration, then out of calibration shall be investigated as per current version

5.0            ABBREVIATIONS:

QC: Quality Control	QA: Quality Assurance
UPS: Uninterrupted Power Supply	Mg: Milli gram
SOP: Standard Operating Procedure	g : Gram