Follow
1.0 OBJECTIVE : To provide a general guideline for operation and function checking of Analytical Balance.
2.0 SCOPE : This SOP is applicable for operation and function checking of Analytical Balance, Model No. AB 204-S/FACT (Instrument ID.: QC/122).
3.0 RESPONSIBILITY
3.1 Operating personnel is responsible for carrying out the procedure.
3.2 Overall responsibility for training, implementation and follow-up with the QC Manager or his / her nominee.
4.0 ACCOUNTABILITY
4.1 Head of Quality.
5.0 PRECAUTIONS
5.1 During and after weighing always close all the windows of the balance.
5.2 Always place the weight in the center of the pan.
5.3 Check the leveling of the balance before every weighing. It must be level on a stable surface.
5.4 Never weigh any material beyond the maximum and minimum weight limits indicated on the balance.
5.5 Keep the balance stable, vibration free position as horizontal as possible.
5.6 Keep the balance free from direct sunlight.
5.7 Keep the balance free from temperature fluctuation.
5.8 Keep it free from heat radiation.
5.9 Keep it free from aggressive chemical atmosphere.
5.10 Keep it free from moist condition.
5.11 The pan of the balance should be checked to ensure that it is properly seated on the pan mechanism.
5.12 Allow samples/containers to reach to room temperature before weighing. Hot samples will generate an upward convection of warm air that will cause an inaccurate reading.
5.13 Samples that are extremely hygroscopic or lose water rapidly must be weighed in a closed container.
5.14 Fingerprint may cause an inaccurate value. Make sure that hands are clean and dry and do not contribute to the weighing.
5.15 Be sure to use a clean and dry spatula or other transfer device to avoid contamination of the article to be weighed.
5.16 Weight shall be taken within the operating range affixed on the balance.
6.0 PROCEDURE
6.1 Plug the AC adapter and connect the power supply. Press the On key briefly. To achieve accurate result the balance must be connected to the power supply for 60 minutes.
6.2 Connect the printer to the balance. Turn On power switch of the printer.
6.3 First person who will start the balance will perform the Internal calibration and function check and maintain a logbook (As per FRM No: FQC/060)
6.4 Internal Calibration
6.4.1 Press and hold Cal/Menu key until CAL appears in the display, then release the key.
6.4.2 The calibration is finished when the message “Internal cal. done” appears in the display. The balance is again in weighing mode and ready for operation. If the printer is connected the result of the internal calibration is automatically printed.
6.5 Daily Function Check
6.5.1 Check the bubble position of the balance and note down in the log book. Adjust the position if required.
6.5.2 Take 200 mg, 50g and 100 g certified weight and clean them carefully with a soft lint-free cloth.
6.5.3 Place the weights, one after another, at the centre of the weighing pan and close all sliding window and allow the reading to be stabilized.
6.5.4 Give entry in the log book of balance (FRM No: FQC/481) for the usage of the balance and Record the value of the weights in the logbook for ‘Daily Function Check of Analytical Balance’ (Annexure-I, FRM No: FQC/060).
6.5.5 The tolerance limit: ± 0.1% to that of specific weight.
6.5.6 The daily function check shall be done at the beginning of each day and the function check shall be valid for 24 hours provided that the balance is not powered off within this period. Before starting to take any weight in the balance, the analyst shall ensure that the function check has been done and it is still within the valid period of time.
6.5.7 During daily function check if it is found that the balance does not meet the tolerance limit, re-adjustment of the balance (Internal calibration) to be done and function to be re-checked.
6.5.8 The function check shall be done on each working day. However, on the holy days, if any balance is used, its function checking must be done prior to use by the analyst.
6.6 Weighing
6.6.1 Pre-requisites for sample weighing
6.6.1.1 For weighing samples, clean weighing paper unit to as appropriate size to be used.
6.6.1.2 The weighing papers are to be kept/stored on the balance table in a container/box keeping the lead of the box closed.
6.6.1.3 Cleaned spatula to be used for transferring samples during weighing.
6.6.1.4 After use, spatula shall be cleaned by washing with soap solution (2.5%) followed by rinsing with purified water. The cleaned spatula shall be dried in the oven for at least 30 min.
6.6.1.5Tablets are to be weight in a cleaned aluminum weighing pan. The pan is to be cleaned with soft tissue before and after weighing.
6.6.1.6 In case any analyst need to re-take the weight of any standard or material for the same test due to an error during weighing/transfer of the weight or for an investigation purpose, entry have to be given in the re-test log book.
6.6.2 Weighing of Solid Material
6.6.2.1 Place an empty material receiver on the balance in the center of the pan.
6.7.2.2 Press “ O/T ” key for tarring. When zero (0.0000 g) reading is displayed, add the material to the receiver and again press “ O/T ” key for re-tarring.
6.6.2.3 Transfer the weighing material to the final flask/container and return the material receiver in the same position on the pan.
6.6.2.4 Now note the weight. This weight represents the weight of transferred material in negative value.
6.6.3 Weighing of Liquid Material
6.6.3.1 Liquid should always be weighted into a material receiver/container that is dry, clean, desiccated and can be closed so that none of the material is lost.
6.6.3.2 Place an empty receiver/container with cap on the balance in the center of the pan.
6.6.3.3 press “ O/T ” key for taring.When zero (0.0000 g) reading is displayed, take the receiver outside the balance, add sample and return on the balance pan.
6.6.3.4Weight adjustment is to be done outside the balance.
6.6.3.5Finally takes print of the weight of sample.
6.6.4 Weighing of semisolid material
6.6.4.1 Place an empty material receiver on the balance in the center of the pan.
6.6.4.2 Press “ O/T ” key for tarring. When zero (0.0000 g) reading is displayed, add the material to the receiver and record the weight.
6.6.4.3Transfer the whole weighing material (e.g. by using a solvent) to the final flask.
6.6.4.4 All weighing is to be recorded in the log book of balance (FRM No: FQC/481).
6.7 Operating Range and Minimum Weight All weighing shall be taken on the balance within the operating range (Affixed on the balance). The operating range of this balance is 200 mg to 100 g. Minimum weight of this operating range is to be verified during quarterly calibration by the following equation.
Minimum Weight = 2000 x SD, Here, SD = Standard deviation of 10 measurement with 100 g standard weight. Minimum weight shall be reported in the Annexure-II.
The calculated minimum weight should always be less than 200 mg (lowest limit of operating range). If any time, the calculated minimum weight is found higher than 200 mg, a new operating range is to be affixed on the balance where lowest limit shall be more than calculated minimum weight.
6.8 Switch Off
6.8.1 To switch off, press and hold the “Off” key down until OFF appears in the display.
6.9 Cleaning
6.9.1 Switch off the balance. Remove all objects from the balance. Clean the pan with soft brush followed by with soft clean cloth.
6.9.2 Clean all of the parts of the balance with clean dry cloth.
6.9.3 Set the parts of weighing pan carefully.
