Standard Operating Procedure for Analytical Balance 220g x 0.1mg Radwag AS 220/C/2.

Standard Operating Procedure for Analytical Balance
Current Version	01
Controlled #	SP-001
Effective Date:

Distribution:

Original to be kept in QMS Office Master File
Testing Lab

Table of Contents

Revision History:

Review #	Revision #	Date	Authorizer	Reason
00	00	Date:01	Name of Authorizer	Document Created

1.0 Objective:

The purpose of this SOP is to describe the procedure of Operation, Calibration, and Maintenance of Analytical balance (Analytical Balance 220g x 0.1mg Radwag AS 220/C/2.) in the Quality Control Department.

2.0 Scope:

This SOP is applicable to the analytical balances for operation and calibration of balances in the Quality Control Department and also applicable to analytical Electronic weighing balances (Analytical Balance 220g x 0.1mg Radwag AS 220/C/2).

3.0 Roles & Responsibilities:

Responsible Personnel	Tasks
QC Analyst/User/Technical Staff	Responsible to perform all The operation, calibration, and maintenance as per the SOP and Maintaining the history card, Instrument usage logbook, weight prints and record all the activities as per the SOP.
QC Analyst/ DQMSM	Responsible to write the SOP and to update the SOP for more GLP Compliance.
QC Manager	Responsible to review and to check the SOP as per the prescribed SOP format and to ensure the implementation of all activities as per SOP. to ensure that the instrument is operated, calibrated and maintained and the related documentation is done as per the SOP.
QA	Responsible to ensure the implementation of the system as per the SOP and supervise all the Technical Procedures as per SOP
Plant Head and Quality Head	Responsible to authorize the SOP and to verify the implementation of all activities as per SOP.

All activities will be performed as per the following responsibilities;

Tasks	Responsible Personnel
Installation	Service Engineer/Supplier
Transportation	DMO/SE
External Calibration	Service Engineer/Supplier/authorized person from ISO 17025 calibration lab
Daily Verification	Analyst/DMO/SE
Preventive maintenance	Analyst /DMO/SE
Service	Service Engineer/authorized person from Service department/ Maintenance department
Weighing of materials	End User/ QC Analyst

4.0 Terms & Definitions:

SOP: Standard Operating Procedure

QMS: Quality Management System

DQMSM: Deputy QMS Manager

TM: Technical Manager

DTM: Deputy Technical Manager

SE: Service Engineer

DMO: Development & Maintenance Officer

GLP: Good Laboratory Practices

Cal Int” : Internal Calibration

“Cal done” : Calibration Done

IPA : Isopropyl Alcohol

NA : Not Applicable

NMT : Not More Than

NIST : National Institute of Science and Technology

Calibration: To align a measurement equipment to read/measure according to a traceable standard equipment under controlled conditions.

Validation: To Check the performance of a measurement equipment.

5.0 Procedure:

All activities will be performed as per the following procedures;

Task before use:

Ensure that balance is on firm, vibration-free position and in a room without temperature fluctuations.
Check that balance is exactly in a horizontal position, compensate it if any minor unevenness in its location by turning two leveling feet at the rear of the balance housing until the air bubble is in the center of the leveling control (internal circle).
Connect the power supply of instrument with the mains and turn power switch “ON”.
Press “ON / OFF” key, the display will show normal weight(0.0000g).
Allow the balance to warm up for initialization 30 minutes.
Press the “O/T” key of the menu bar, the display shows “0.0000 g”.
If we are working with butter paper/container, place it on the weighing pan, close the glass draft shield, then press the “O/T” key to tare the scale.
Press the “Print” key from the menu bar, to take a printout of the printer is attached.
Before executing the tests, the analyst should place the weights in the vicinity of the balance for an appropriate time to reach sufficient thermal equilibrium.
If possible, Carry out all tests with a single test weight in order to minimize handling errors, but multiple test weights are permitted.

5.1 Weighing Procedure – Good Weighing Practices

Select an appropriately sized butter paper or receiver based on the quantity of sample to be weighed.
Carefully add the desired quantity of sample to the center of the butter paper or receiver.
Ensure that the weight of the sample measured falls within ±10% of the specified weight, unless otherwise specified in the relevant monograph or procedure document.

5.2 Addition weighing – Good Weighing Practices

Addition weighing is suitable for solid or non-volatile liquid samples.

Place the empty butter paper or receiver on the balance pan, ensuring it is centered, and press the tare (Zero) key to zero the balance (after stabilization of the indicator).
Add the desired amount of material to the butter paper or receiver.
Allow the balance to stabilize and display a steady reading (after stabilization of the indicator).
Record the weight displayed on the balance.
Transfer the weighed material to the final flask or beaker as required.
Without changing the tare setting on the balance, reweigh the original butter paper or receiver by placing it back in the same position on the pan.
The difference between the two weights represents the weight of the transferred material.

5.3 Dispense Weighing – Good Weighing Practices

Tare the balance (on stabilization of indicator).
Place the sample container (bottle, tube, transfer pipette, or syringe) on the balance in the center of the pan and record the weight (on stabilization of indicator).
Transfer the desired amount of material to the final flask or beaker as required.
Reweigh the sample container without changing the tare setting on the balance.
The difference between the two weights represents the transferred material weight.

5.4 Liquid and Volatile Material Weighing – Good Weighing Practices

Place the empty receiver (add diluent if material is highly volatile) on the balance in the center of the pan and tare the balance (on stabilization of indicator).
Add the desired amount of material to the receiver.
The displayed weight, on stabilization of the indicator, represents the transferred material weight, which should be printed and kept with the raw data.

5.5 Hygroscopic Samples – Good Weighing Practices:

Weigh hygroscopic samples promptly or in a gas-tight vessel.
Tare the vessel and its enclosure.
Add the desired amount of sample, replace the enclosure, and record the weight.
The difference between the two weights represents the transferred material weight.

5.6 Viscous Liquid Material Weighing – Good Weighing Practices

Place the empty receiver on the balance in the center of the pan and tare the balance (on stabilization of indicator).
Add the viscous material slowly to achieve the required volume.
The displayed weight, on stabilization of the indicator, represents the transferred material weight, which should be printed and kept with the raw data.

5.7 Semi-Solid Material Weighing – Good Weighing Practices

Place the empty receiver on the balance in the center of the pan and tare the balance (on stabilization of indicator).
Transfer the approximate required quantity of semi-solid material to the receiver using a capillary tube or spatula.
The displayed weight, on stabilization of the indicator, represents the transferred material weight, which should be printed and kept with the raw data.
Alternatively, place a clean and dry glass coverslip on the balance, tare the balance (on stabilization of indicator), transfer the semi-solid material onto the coverslip, record the displayed weight, and then transfer the coverslip directly into the receiver.

5.8 Warm or Cool Samples – Good Weighing Practices:

Equilibrate warm or cool samples to room temperature before weighing.
Note that warm samples may appear lighter due to heat convection.

5.9 Aseptic or Bio-hazardous Materials Weighing – Good Weighing Practices

Perform weighing of sterile or bio-hazardous samples within a clean bench, biosafety cabinet, isolator, or similar containment device.
Qualify the balance’s performance in the environment to ensure stability.

5.10 Corrosive Materials Weighing – Good Weighing Practices

Avoid spilling corrosive materials on the balance pan or inside the balance housing.
Take extra precautions when handling such materials to prevent damage.
Depending on the nature of a spill, re-qualification of the balance may be necessary.

6.0 Installation of Analytical weighing balance:

6.1 Power requirement:

Select an installation site that is near a power source to allow the attachment of the AC adapter. Verify that the power voltage conforms to that indicated on the AC adapter.

6.2 Installation site:

The balance must be installed in a proper place to ensure safe and accurate measurements. The installation site should be level, and the equipment should be adjusted so that the bubble in the level is centered by adjusting the screws on the levers. Avoid the following types of sites.

Air currents from air conditioner, ventilators, open doors, or windows: Avoid placing the equipment where it will be affected by air currents from HVAC systems, open doors, or windows, as these can affect its operation or measurements.
Vibrations: Choose a location free from vibrations to ensure stable operation of the equipment and accurate measurements.
Direct sunlight: Avoid placing the equipment in direct sunlight to prevent overheating and potential damage to sensitive components.
Extreme temperature changes, high/low temperature, or high/low humidity: Select a site with stable temperature and humidity levels within the recommended operating range to maintain equipment performance and reliability.
Near flammable and corrosive gases: Keep the equipment away from areas with flammable or corrosive gases to ensure safety and prevent damage to the equipment.
Dust, electromagnetic waves, or magnetic fields: Minimize exposure to dust, electromagnetic waves (EMF), or magnetic fields, as these can interfere with sensitive equipment or affect measurements.
Space for opening glass doors: Ensure there is sufficient space around the equipment, especially if it has glass doors that open backwards, to allow for full and safe opening without obstruction.

6.3 Calibration/Verification

Calibration is required to accurately weigh the items with an electric balance.

Parameter wise Balance Calibration Frequency :

Internal Adjustment: Frequency: Perform on every working day, after a power failure, after any maintenance and relocation of balance.
Verification Check: Perform on every working day, after a power failure, after any maintenance and relocation of balance.
Linearity: Calibration Frequency: Perform on every working day, after a power failure, after any maintenance and relocation of balance.
Sensitivity: Frequency: Monthly and after any maintenance and relocation of balance.
Repeatability (Uncertainty): Frequency: Monthly and after any maintenance and relocation of balance.
Accuracy: Frequency: Monthly and after any maintenance and relocation of balance.
Eccentricity: Frequency: Monthly and after any maintenance and relocation of balance.

Calibration requires prior authorization and should be done by authorized staff member declared to be competent to perform Calibration. Calibrations must be performed using traceable standard weights (NIST) whose calibration has been performed by an ISO 17025 accredited calibration laboratory. Before starting and at the end of calibration, premises temperature and humidity should be noted.

6.3.1 Procedure of calibration:

Perform calibrations after only correct installation and through warm up, also make sure that nothing is on the pan and ensure conditions free form influence of vibrations and wind.

The weight class chosen for the calibration should be such that the tolerance of the weights used does not exceed 0.1% of the amount weighed.
The weights used for calibration shall be calibrated against standard weights traceable to NIST.
All the weights taken should be ± 10% of the target weight as specified in the individual monograph.
The analyst shall always use the calibrated weight box for calibration purposes.
Calibrate weight boxes by outside agency yearly ± 30 days.
After the receipt of the calibrated weight box along with the calibration certificate limit for allowable tolerance limit (for external calibration) should be calculated as minimum and maximum weight from the limit in terms of % mentioned in Attachment-1 for all the weight which require for the calibration.
e.g. Actual mass value found after calibration is 200.0050 gm, then 199.8050 gm to 200.2050 gm is the minimum and maximum weight limit as per ±0.1% of the actual mass value.
Every time after calibration of weight box format of Annexure -1 shall be reprinted and implemented including following.
- Minimum and Maximum limit calculated as above for all weights
- Weight box no
- Valid up to date
- Actual mass value & theoretical weight
- Weight box no.
- Valid up to date.

After calibration submits the raw data for checking.
The analyst shall update the calibration status label and make an entry in the instrument usage log book.
If the weight print facility of balance is not working, then inform the service engineer for rectification of this problem.
Till rectification of this problem, Check the weight during weighing and signed by the section head.
If print facility available attach the print out with a template.
In case the weight prints taken are not considered in the calculation ( e.g due to unclear visibility, misprinting, not as per defined statistics mode or weighing mode, etc.),
Attach such weight prints in the template and write justification against the weight print on the respective template.
Take fresh standard/ sample weights for the batch to continue the analysis.
If the calibration status label is not provided by the certified agency then affix the label on the weight box

6.3.2 Internal Adjustment/Span Calibration– Balance Calibration:

From the main display press the [CAL] key once. If the display shows i-CAL (preset calibration method is (i-CAL) start from “Recheck that there is nothing on the pan and wait.” If the display shows another item (the present method is not i-CAL) Press the [CAL] key repeatedly until “FUNC. SEL” appears, then, press the [O/T] key to display the [CAL].
Press the [O/T] key again, the display shows “E- CAL”.
While “E-CAL” appears, press the [O/T] key. Span calibration begins and zero display blinks.
Recheck that there is nothing on the pan and wait.
The set weight value appears blinking.
Place the weight indicated on the pan. Wait until the blinking zero display appears.
Remove the calibration weight. After “CAL End” appears for several seconds, the display returns to the mass display and the span calibration is complete.

6.3.3 Verification check

Daily or pre-use verification of the analytical weighing balance will be performed by authorized competent staff member. If the balance is turned off, validation is required again after switching on the balance. Following is the procedure for daily validation.

Plug in power supply (If the balance is not switched on).
Balance will start a Self-Check as [CAL 2], [CAL 1],[ CAL 0], [CAL End], OFF.
Press power key.
Balance will show 0.0000g on display.
Open one of the glass doors of the weighing chamber. Place the weighing vessel on the pan and close the glass door again.
Wait the display to stabilize and press the [0/T] key. The appearance of the stability mark indicates a stable state. The display will read zero.
Open the glass door and place standard weight of 200mg on the weighing pan and weight until reading gets stable.
Note the value and note in the respective log book for daily balance verification.
Repeat the procedure with standard weights of 1000mg, 5000mg and 20gm. (or to cover entire weighing range.)
Note all the values in log book with date and signatures or attach printout if available (Press ‘Print’ key every time instead of writing the value).
Report if the values do not fall within the mentioned reference limit.

6.3.4 Linearity – Balance Calibration:

Allow the balance to stabilize in the environment where it will be used for testing

Ensure the analytical weighing balance is clean and calibrated according to the manufacturer’s instructions.
Carry out the Linearity using Calibrated weights: 100 mg, 200 mg, 500 mg, 1 g, 5 g, 10 g, 20 g, 50 g, 100 g, and 200 g. (Note you may modify according to your working range)
Calculate the deviation for each recorded weight compared to the expected weight:
Place each calibration weight sequentially on the pan of the balance and record the displayed weight after stabilization in template.
Step 2: Calculation of Deviation
- Calculate the deviation for each recorded weight compared to the expected weight:
  Deviation(g) = W (measured) – W_(expected)

Template (Annexure-1) for Linearity Testing:

Weight (g)	Expected Weight (g)	Measured Weight (g)	Deviation (g)	Percentage Deviation (%)
0.100
0.200
0.500
1.000
5.000
10.000
20.000
50.000
100.000
200.000

Enter the values for expected and measured weights during testing.
Calculate deviations and percentage deviations for each reading.
Summarize average percentage deviation and compare against the acceptance criteria.
If the average percentage deviation meets the acceptance criteria (±0.05%), the balance is deemed linear for the tested weights.
If not, perform necessary adjustments or maintenance and retest until compliance is achieved.
Frequency:
- Perform linearity testing:
- Upon initial installation of the balance.
- After any major maintenance or adjustments.
- At regular intervals as per your organization’s calibration schedule (e.g., annually).

6.3.5 Sensitivity – Balance Calibration:

Sensitivity Test Procedure

Place the 200 g weight on the pan of the balance.
Record the displayed weight after stabilization.
Calculate the deviation compared to the actual mass value:
Deviation (g) = W_measured – 200 g
Ensure deviation does not exceed +0.5% of the actual mass value.

Measurement Uncertainty Calculation

Perform measurements using the 200 mg and 200 g weights separately.
Record the displayed weights after stabilization.
Calculate the measurement uncertainty using the following formula:
Uncertainty (g) = K × √(Σ(W_i – W_mean)² / (n – 1))
Where:

W_i = individual measured weight
W_mean = mean of the measured weights
n = number of measurements
K = coverage factor (typically 2 for a 95% confidence level)

6.3.6 Repeatability – Balance Calibration

Repeatability Calculation

For 200 mg Weight:

Calculate the standard deviation (σ) of the 10 replicate measurements for the 200 mg weight.
Calculate the repeatability (R) using the formula:
R = (Standard deviation × 2) / Actual weight of the standard weight
If the calculated standard deviation is smaller than 0.41d (where d is the scale interval), replace it with 0.41d.
Ensure repeatability is not more than 0.001 or 0.10% and measurements are within ± 10% or 0.0010 of the actual weight.

For 200 g Weight:

Calculate the standard deviation (σ) of the 10 replicate measurements for the 200 g weight.
Calculate the repeatability (R) using the formula:
R = (Standard deviation × 2) / Actual weight of the standard weight
If the calculated standard deviation is smaller than 0.41d (where d is the scale interval), replace it with 0.41d.
Ensure repeatability is not more than 0.10% and measurements are within ± 10% of the actual weight.

6.3.7 Eccentricity – Balance Calibration

Eccentricity Test Procedure

Perform the Eccentricity test using the following steps:

Place the 200 g weight at the center of the balance pan.
Record the displayed weight after stabilization.
Move the 200 g weight to different positions on the balance pan (front left, front right, back left, back right).
Record the displayed weights after stabilization for each position.

Calculation of Eccentricity

Calculate the deviation (E) for each position compared to the weight at the center:
E = W_measured – W_center
Find the maximum deviation (E_max) among the recorded deviations.

Acceptance Criteria:

Eccentricity (E_max) should not exceed ± 0.10% of the actual mass value.

Figure-2-Eccentricity-Balance-Calibration

7.0 Preventive Maintenance and Cleaning:

Before using check BUBBLE in CENTRE status.
Avoid air currents, shakers, sonicators, magnetic stirrers, centrifuge machines by working in near vicinity or same desk for accurate weighing.
Use dry spatulas and petri dishes for weighing.
CLEAN immediately in case of splashes or spills on it.
“DO NOT LEAVE” any chemical bottle, notebook, remainder samples etc. near it after usage.
Weigh liquids in closed vessel.
REPORT immediately to lab in charge in case of any breakage, non functioning or atypical behavior of the instruments.
Except when placing or removing items to be weighed or calibration weights to and from the chamber keep the glass door closed.
Transportation: “DO NOT” change weighing balance location even not within the room/lab. Inform authorized staff members for transportation or call vendor.
Clean the balance with damp cloth by gentle wiping the smudge of dirt.
Remove the weighing pan from the measuring chamber for cleaning, otherwise it may damage the weighing system.

8.0 Precautions:

All activities must be performed as per SOP by trained personnel only.
Record all activities as per SOP in the respective forms.
Balance must be placed on a stable/flat surface.
Check the bubble prior to use.

9.0 Related Documents:

Analytical Balance Utilization Log Book (EQ-LB-001)
1. Weighing Balance Verification Log Book (EV-LB-001)
1. Standard procedure for calibration/qualification of equipments (SP-01)

References:

Manual for use of Analytical weighing balance (Analytical Balance 220g x 0.1mg Radwag AS 220/C/2)
the general chapters (GC) <41> and <1251> of the USP are widely recognized as standards for managing balances, and how a minimum weight is calculated is also stipulated in these chapters.
According to the general chapters <41> “Balances”, a balance used for samples that necessitate accurate weighing must be
calibrated over the operating range and meet requirements defined for repeatability and accuracy.