This document details the procedure for the operation and calibration of the pH meter. It is the policy of pharmaceuticals that the written procedure shall be followed for the operation and calibration of pH Meter in order to ensure smooth operation and its use monitored to obtain consistent and reproducible results to minimize downtime and to meet regulatory requirements.
This procedure is to be applied at the time of operation and
calibration of the pH meter.
4.0 RESPONSIBILITYÂ & ACCOUNTABILITY
Persons along with their responsibilities and account-abilities are
given below:
|
S. No |
Designation |
Responsibility  |
|
01 |
Executive - Corporate Quality Assurance |
To prepare the SOP and follow the same  |
|
02 |
Trainee Analyst/ Jr. Analyst/ Analyst/ Sr. Analyst |
To follow the SOP accordingly |
|
03 |
Manager - Quality Assurance |
To ensure implementation of SOP. |
|
04 |
Manager-Â Quality Control |
To ensure implementation of SOP.   |
|
05 |
Manager    Â
-Â Â Â Â Â Technical |
To ensure implementation of SOP. Â |
|
06 |
VPÂ Â Â Â Â Â Â Â Â Â Â Â Â
-Â Â Â Â Â Â Technical |
To ensure implementation of SOP. Â |
|
07 |
Manager – Corporate Quality Assurance |
To ensure implementation of SOP. |
5.0Â General instructions
5.0.1Â Check the validity of the buffer solutions before
use.
5.0.2Â After calibration do not switch off the pH meter.
If done so, again calibrate the pH meter before use.
5.0.3Â To remove excess water from the electrode
gently touch it over with a small piece of filter paper/ tissue paper. Never
rub the electrode with filter paper/tissue paper.
5.0.4Â If the pH meter is not in use for more than 48 hours,
then immerse the electrode in saturated aqueous Potassium Chloride solution.
5.0.5Â for regeneration, periodically dip the pH
electrode in 1M HCL for 10-15 minutes and then rinse with purified water. Check
the liquid in the electrode, the electrode filament should be dipped completely
in the liquid; if not saturated potassium chloride solution should be injected
up to the required level.
Cleaning of pH meter
Disconnect the apparatus from the main power supply.
Clean the apparatus externally with the help of a clean dry
cloth daily. If required clean with a wet cloth followed by a dry cloth.
Clean the electrode with Purified water. If required immerse the electrode in 0.1 M HCL or 0.1 M HNO3Â for 30 minutes. After immersing
the pH electrode in an acidic solution wash with Purified water properly.
5.2 Precautions of pH meterÂ
5.2.1 Do not leave the electrode dry. Keep
the electrode in a storage medium (slightly acidic Solution).
5.2.2 Do not wipe the glass electrode bulb
with any coarse material. Use only tissue paper.
5.2.3 The buffer solution should not
get contaminated and should not be used after one month.
5.2.4 Before preparing of new Buffer
solution discard the previous buffer solution and if there is haziness in the buffer due to fungal growth discard the solution and prepare a fresh buffer.
5.3 CALIBRATION PROCEDURE
5.3.1 Calibrate the pH meter at the start
of each working day before use.
5.3.2 Switch on the pH Meter, allow
it to stabilize for 15 minutes, and follow step 5.4.
5.3.3 Rinse the electrode with
Purified water.
5.3.4 Calibrate the instrument by using a buffer solution.
5.3.5 PREPARE THE BUFFER SOLUTIONS AS PER REQUIREMENT
AND STORE THEM IN PLASTIC BOTTLES OR USE COMMERCIALLY AVAILABLE LIQUID BUFFER
SOLUTIONS
5.3.6Â Â Preparation of Buffer Solutions
5.3.6.1 Acid Phthalate buffer (pH 4.01)
5.3.6.2 Place 250 ml of potassium bi-phthalate solution in a 1000ml volumetric flask, add 0.5mL of (0.2M) hydrochloric acid solution and add
water to the volume.
5.3.6.3 Record the preparation details of buffer solution on SOP Preparation of stock (Buffer) solution, once a month, and store at room temperature in plastic bottles.
5.3.6.4Â Phosphate buffer (pH 7.01)
5.3.6.5 Place 250 ml of the monobasic potassium phosphate
solution in a 1000 ml volumetric flask, add 145.5 ml of sodium hydroxide (0.2M)
NaOH, then add water to the volume
5.3.6.6 Record the preparation details of buffer solution on SOPÂ Preparation of stock (Buffer) solution,Â
once in month and store at room temperature in plastic bottles
5.3.6.7 Alkaline Borate Buffer (Ph 10.01)
5.3.6.8 Place 250ml of the boric acid and potassium chloride
solution in 1000ml volumetric flask, add 218.5 volume of sodium hydroxide solution
(0.2M NaOH) then add water to volume
5.3.6.9 Prepare buffer solutions on SOP Preparation of stock(Buffer) solution, once in month and
store at room temperature in plastic bottles
5.3.7 Transfer 100 ml of each stock buffer
solution in 100 ml individual plastic bottles for daily calibration and
record the transfer volume on SOP as Preparation and Transfer
record Appendix for pH 4.01, for pH 7.01 record the transfer volume
on SOP as Preparation and transfer record Appendix and for
pH 10.01 record the transfer volume on SOP as Preparation and
Transfer record
5.3.8 For Daily calibration transfer the
required volume in the beaker from 100 ml plastic bottles and again pour this
buffer solution in the plastic bottle after use.
5.3.9 After one week discard the buffer
solution from a 100ml plastic bottle and again fill this bottle with the stock buffer solution Â
5.3.10Â alternatively, uses commercially available
liquid buffer solutions and follows step 5.3.7.
5.3.11Â Allow solutions to attain room temperature
before being used for calibration by using the temp knob provided on your
instrument.
5.3.12Â Connect the electrode to the pH meter (if not
connected). Select buffer solutions of pH 4.01, 7.01 10.01.
5.3.13Â Immerse the electrode in the buffer solution pH
4.01Â Wait till the screen shows a stable value and press the Call key.
5.3.14Â Rinse the electrode with Purified water, blot
out the water with tissue paper/ filter paper, and place it into a buffer solution.
Wait for a stable pH reading and ready signal to appear on the display and
perform the same till the last buffer value has been entered
5.3.15 The same procedure is repeated for buffer solution
of pH 7.01,10.01.
5.3.16 pH meter is calibrated if pH readings differ by not
more than 0.05 from the set reading and record the observations
5.3.17 Record the Calibration Data on CQA/SOP-050/FR-02 as the Daily Calibration Record of pH Meter Appendix
II.
5.3.18 Compare the result with acceptance criteria and take
valid calibration authorization from the Section Incharge.
5.3.19Â Report any discrepancy observed during the operation
and calibration of the instrument to the Section Incharge or his representative for
corrective and preventive action.
5.3.20 Section Incharge or his representative will report
the same to the Manager – Quality Assurance and notify the defect to service
engineer to rectify the defect.
5.3.21 Affix the ‘Out of Order’ label on the instrument.
5.4 PROCEDURE
5.4.1 Switch On the pH meter from the main
power.
5.4.2 Use the ON / OFF key present at the backside of the pH meter.
5.4.3 The following keys are used during
operation and calibration.Â
For pH measurement, first, check the calibration of the pH meter as
mentioned in 5.3.1 to 5.3.22. Rinse the electrode with Purified water and ensure
that the pH meter is in measure mode (by pressing the Result key) to measure the pH of the test
solution.
5.4.6 Dip the electrode tip in the test
solution.
5.4.7 Wait for a stable pH reading and ready to
appear on display.
5.4.8 Rinse the electrode with Purified
water.
NOTE-Do does not immerse the entire electrode in the solutions; only the tip of the electrode should be Dipped.
5.4.9 Maintain Logbook of pH meter CQA/SOP-050/FR-01 Logbook of pH meter (Appendix I).
 5.5 STORAGE OF ELECTRODE
5.5.1 For a fast response of the pH
electrode during sample measurement, the electrode is to be immersed in a
slightly acidic solution.
PH electrodes should always be stored in a moist condition,
in either a 7.00-pH buffer with potassium chloride solution (200 ml of buffer
pH 7.0 with 1.0 gm Potassium Chloride) between routine measurements. The electrode should not store in distilled or de-ionized water.
APPENDIX
IÂ Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â /CQA/SOP-050/FR-01
LOGBOOK OF pHÂ METER
Instrument
ID: ----------------------------
Location: ----------------------------
APPENDIXÂ
IIÂ Â Â Â Â Â Â Â Â Â Â Â /CQA/SOP-050/ FR-02
DAILY
CALIBRATION RECORD OF pH METER
Instrument
Id: ------------------------------
Location: ------------------------------Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â
|
Date |
Observed
pH of buffer solution used |
 Done
by |
Checked
by |
Remarks |
||
|
pH
4.01 ±0.05 (3.96
- 4.06) |
pH
7.01 ±0.05 (6.96
-7.06) Â |
pH
10.01 ± 0.05 (9.96
-10.06) |
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