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CALIBRATION OF
WEIGHING BALANCE

AND APPARATUS

Presented by: Submitted to:

Dipak Kumar Gupta Dr. Gaurav Jain

M.Pharm(1st sem) Dept. of pharmaceutics
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WHAT IS CALIBRATION ?

Calibration is the activity of checking, by comparison

with a standard, the accuracy of a measuring

instrument of any type. It may also include adjustment

of the instrument to bring it into alignment with the

standard.

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PURPOSE OF CALIBRATION

Calibration is primarily done to achieve 5 main purposes which are:

• To make sure that the readings of equipment or instruments are
consistent with other measurements and display the correct

• To determine the accuracy, precision, reliability and deviation of
the measurements produced by all the instruments

• To establish the reliability of the instrument being used and
whether it can be trusted to deliver repeatable results each time

• To map the ‘drift’ as documented. Instruments have a tendency
to produce inaccurate measurements over a period of time,
following repeated use.

• Ensuring that the industry standards, quality assurance
benchmarks such as current good manufacturing practice

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(cGMP) and government regulations are adhered to.

Precision is the degree to which repeated measurements

under unchanged conditions show the same result.

Accuracy is the degree of closeness of measurements of a

quantity to its actual true value

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FREQUENCY OF CALIBRATION

• How often you conduct calibration mainly depends upon its

tendency to drift from the true measurement and how it

impacts the quality of the end product. Examine each

instrument being used and study its behavior. Based on this

information, you can design a calibration schedule for each

instrument. The interval between calibrations can vary as:

Weekly

Monthly or bi-monthly

Quarterly, semi-annually or annually

After every heavy usage of the instrument
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Calibration of Weighing Balance

 Before calibrating the balance, clean the weighing platforms.

 Take the standard weights of different capacity based on the capacity

of the balance as mentioned in table .

 Switch ‘ON’ the main power supply.

Wait till zero reading is displayed on the screen.

 Allow to stabilize for 15 to 20 seconds and then select the weight for

calibration.

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 Place the standard weight on the platform, the display should be

same or within one least count., as per weight placed.

 Record the observations in balance calibration record format.

 If the display is not matching to the weight placed and the difference

is more than one least count than open the side pot and adjust with the

screwdriver till it matches.

 If the reading is not coming within one least count put an out of order

label and get it rectified by the service engineer. Do not use the

balance till it is rectified.

 Note: Always use standard weights, which are certified by Weights

and Measure Department. 7

Calibration of Apparatus

1. Clean and rinse 3 volumetric flasks of appropriate size (25.00 or 50.00 mL).
Rinse the flasks 2 or 3 times with small (~2 mL) portions of acetone, making sure
that you cover all inside surfaces with the acetone rinses, and discard these
rinses. Allow the residual acetone to evaporate. Clearly label each flask, using
the white space on the flask and a pencil.

2. After the analytical balance has been leveled and
calibrated, tare the balance. Determine the mass of
each flask and its stopper, and record these masses
in your notebook. Make sure that you tare the

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3. Dispense a suitable volume of deionized water into a beaker, and

measure and record the temperature of the deionized water. Use the

table in your textbook and the water temperature to determine the

correct density of water. Fill each of the flasks with deionized water to

the fill line. Mass the filled flasks, making sure to record the masses of

4. Return the deionized water to your beaker. Rinse the flasks 2 or 3

times with acetone as described in step 1. When the residual acetone

has evaporated, repeat steps 2 and 3 until you have made triplicate

measurements of the mass of water contained by each of the three flasks.

5. Calculate the corresponding volumes of water contained by each of

the flasks, and calculate the mean and sample deviation for each flask.

When you are done, you should have a data table similar to that show9 n

below.

Pipette

1. Clean and rinse 3 pipette. Label the pipets so that you can tell them apart.

2. Measure the mass of a suitably sized beaker (~50 mL) on the analytical
balance, and record the mass.

3. Rinse the first pipette 3 times with deionized water by filling the pipette to
the fill line, and discarding the rinse. Finally, fill the pipette to the fill line,
wipe excess water from the outside of the pipette with a Kimwipe® and
dispense this liquid into the beaker. Measure and record the mass of beaker
and water, discard the water, and dry the beaker. Repeat this procedure until
you have triplicate measurements made for each pipet. The mass of water
dispensed from the pipet is found by subtracting the empty weight of the
beaker from the weight of the beaker and water.

4. Calculate the corresponding volume of water delivered by each pipet, and
calculate the mean and sample deviation for each pipet.

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