1.0 OBJECTIVE:
To
lay down the calibration procedure for reliable and accurate results.
2.0 SCOPE:
This
shall be applicable to the pH
meter of Quality Control Laboratory.
3.0 RESPONSIBILITY:
3.1
Technical
Assistant/ Helper.
3.2
Q.C Analyst.
4.0 ACCOUNTABILITY:
4.1
Manager-Quality
Control.
5.0 MATERIAL AND
EQUIPMENT:
5.1
pH meter.
5.2
Analytical
weighing balance.
5.3
Magnetic stirrer.
5.4
desiccator
5.5
Glassware (6
beaker of 1000.0ml, 2 beakers of 100.0ml, 1 pipette, 1 stirrer, spatula).
5.6
Standard certified
buffer bottle of pH 4.00 and 7.00.
5.7
Potassium hydrogen
phthalate 10.13g.
5.8
Potassium
dihydrogen phosphate 3.39g.
5.9
disodium hydrogen
phosphate 3.53g
5.10 Disodium
tetraborate 3.80g.
5.11 Calcium
hydroxide.
5.12 Carbon
dioxide-free water.
6.0 PROCEDURE:
6.1
Firstly clean the
pH meter with clean dry cloth, according to SOP.
6.2
Operate the pH
meter according to SOP for operation of pH meter i.e. SOP.
6.3
Use certified
standard pH buffer to set the instrument at pH 7.00 (with 7.01 pH buffer) and
pH 4.00 (with 4.01 pH buffer) at 25oC.
6.4
Take 2 beakers of
100.0ml add buffer pH 4.0 & 7.0 separately, from the certified buffer
bottle in a glass bottle. Discard the standard pH buffer after one month.
6.5
Prepare different
pH solutions.
6.5.1
Potassium
hydrogen phthalate 0.05M:
6.5.1.1
Firstly weigh
potassium hydrogen phthalate 10.13g by using analytical weighing balance,
operate it according to SOP.
6.5.1.2
Dry the potassium
hydrogen phthalate sample for 1hr at 110±2oC in desiccator
previously.
6.5.1.3
Take a beaker of
1000.0ml and add potassium hydrogen phthalate 10.13g in sufficient Carbon
dioxide-free water, stir it by using magnetic stirrer.
6.5.1.4
Dilute it to
1000.0ml with the same solvent.
6.5.2
Potassium
dihydrogen phosphate 0.025M+disodium hydrogen phosphate 0.025M:
6.5.2.1
Weigh potassium
dihydrogen phosphate 3.39g & disodium hydrogen phosphate 3.53g by using
analytical weighing balance, operate it according to SOP.
6.5.2.2
Dry both the
potassium dihydrogen phosphate & disodium hydrogen phosphate samples for 2hr
at 120±2oC in desiccator previously.
6.5.2.3
Take a beaker of
1000.0ml and add potassium dihydrogen phosphate 3.39g & disodium hydrogen
phosphate 3.53g in sufficient Carbon dioxide-free water, stir it by using
magnetic stirrer.
6.5.2.4
Dilute it to
1000.0ml with the same solvent.
6.5.3
Disodium
tetraborate 0.01M:
6.5.3.1
Weigh disodium
tetraborate 3.80g by using analytical weighing balance, operate it according to
SOP.
6.5.3.2
Take a beaker of
1000.0ml and add disodium tetraborate 3.80g in sufficient Carbon dioxide-free
water, stir it by using magnetic stirrer.
6.5.3.3
Dilute it to
1000.0ml with the same solvent.
6.5.3.4
Store protected
from atmospheric carbon dioxide.
6.5.4
Calcium
hydroxide, saturated at 25oC:
6.5.4.1
Take an excess of
calcium hydroxide.
6.5.4.2
Take a beaker of
1000.0ml and add excess of calcium hydroxide in sufficient Carbon dioxide-free
water, stir it by using magnetic stirrer.
6.5.4.3
Store protected
from atmospheric carbon dioxide.
6.6
Check the pH of
above buffer solutions. It should be within ±0.07. Record the value in the
prescribed Annexure-2.
6.7
Check the pH of
certified buffer pH 4.0 & 7.0. It should be within ±0.02 pH limit of
labeled value. Record the value as per Annexure-2.
6.8
Discard buffer
solution 6.5.1, 6.5.2 & 6.5.3 after 3 month.
6.9
Record the result
on the “Calibration Record”,
“Calibration Log Book” & paste the “Calibration
Status Sticker” on pH meter.
6.10 Frequency of
calibration: 15 days.
6.11 Daily calibration:
6.11.1 Repeat
the same procedure for daily calibration of pH meter using solution 6.5.1,
6.5.2 & 6.5.3 and record value as per Annexure-1.
6.12 If
it is out of specified limit, follow the S.O.P.
6.13 pH meter
temperature sensor:
6.13.1
Keep the
temperature sensor probe of reference calibrated digital thermometer in the
beaker containing purified water of about 35oC.
6.13.2
Add cold purified
water slowly drop wise and bring the temperature between 27oC to 30oC.
6.13.3
Compare the
temperature shown by reference calibrated digital thermometer and pH meter
& record it in format as Annexure-3.
6.13.4
Add purified water
in some more quantity slowly drop wise to bring the temperature between 26oC
to 23oC.
6.13.5
Compare the
temperature shown by reference calibrated digital thermometer and pH meter
& record it in format as Annexure-3.
6.13.6
Add cold purified
water slowly drop wise and bring the temperature between 20oC to 22oC.
6.13.7
Compare the
temperature shown by reference calibrated digital thermometer and pH meter
& record it in format as Annexure-3.
6.13.8
Acceptance
criteria: ±3oC.
6.13.9 Frequency of
calibration: Twice in year.
7.0 REVISION LOG:
|
Revision No.
|
Effective Date
|
Reason
|
|
00
|
|
New
SOP
|
8.0 REFERENCES:
8.1 The British Pharmacopoeia. Vol V., Official Monograph /
Determination of pH values: 2015, pp. 252-253.
9.0 ANNEXURES:
Annexure 1: Daily
calibration record.
Annexure 2:
Calibration record of pH meter.
Annexure 3: pH
meter temperature sensor records.
Annexure: 1
Daily
calibration record
|
Name
of the Instrument: ________________
Make:
________________________________
Model
No.: ____________________________
Identification
No.: ______________________
Primary
Standard: Certified buffer (pH 4.00 & pH
7.00).
Observation Chart
|
Annexure:
2
Calibration
record of pH meter
|
Name
of the Instrument: ________________
Make:
________________________________
Model
No.: ____________________________
Identification
No.: ______________________
Primary
Standard: Certified buffer Primary Standard:
Certified buffer (pH 4.00 & pH 7.00).
Batch
No.: ___________ (pH 7.00).
Batch
No.: ___________ (pH 4.00).
Observations
Remarks:
_______________________________________________________________
Calibration
date: __________________ Calibration
due date: __________________
Calibrated
by: ____________________ Checked
by: _________________________
|
Annexure: 3
pH meter temperature
sensor records
|
Ref. No.: ________________
Issue date: ______________
Issued by: _______________
Calibrated
ref. digital thermometer: ____________________
Ref.
thermometer calibration date: _____________________
Ref.
thermometer certificate No.: _______________________
Ref.
thermometer calibration due date: __________________
pH
meter ID. No.: ____________________________________
Observations
Remarks:
__________________________________________________________________
Calibration
date: _____________________
Next
calibration date: _________________
Calibrated
by: _______________________
Checked
by: _________________________
|
||||||||||||||||||||
10.0
ABBREVIATIONS:
|
Abbreviation
|
Expanded Form
|
|
SOP
|
Standard operating
procedure
|
|
&
|
And
|
|
No.
|
Number
|
|
Ltd.
|
Limited
|
|
Q.C
|
Quality control
|
|
Q.A
|
Quality assurance
|
|
QCEB
|
Quality control
equipment calibration
|
|
ml
|
Milliliter
|
|
g
|
Grams
|
|
oC
|
Degree centigrade
|
|
M
|
Molar
|
|
B.P
|
British pharmacopoeia
|
|
Vol
|
Volume
|
|
Ref.
|
Reference
|
|
ID.
|
Identity
|