1.0 Objective:
The objective of this standard
operating procedure is to lay down the procedure for
operating the pH Meter (Bench).
2.0 Scope:
This SOP covers
operating procedure of pH METER.
3.0 Responsibility
Jr.ResearchOfficer,
Research Officer: Responsible for operation, calibration and
maintenance of the
instrument as per procedure.
Head of Department:
Responsible for calibration and maintenance, timely as per schedule.
QA
officer/QAManager: Review the records and governing the document.
4.0 Procedure:
4.1 Procedure for pH
measurement:
4.1.1 Turn the instrument on
by pressing the ON/OFF Switch on the rear panel.
4.1.2 All LCD tags are displayed and a beep is sounded while the
instruments perform a self test.
4.1.3
The instrument will display
“LoAd” message and blinking until initialization is complete.
4.1.4
To take a pH measurement
removes the electrode protective cap and simply submerses the electrode and the
temperature probe (3cm) into the sample to be tested.
4.1.5
The pH is displayed on the primary LCD and the temperature on the
secondary LCD.
4.2 Procedure for
calibration of pH meter: (Three point
calibration).
4.2.1 Switch on the pH
meter.
4.2.2 Press ‘CALIBRATE’
Key to start calibration.
4.2.3 Calibrate the pH
standard solution at 25°C.
4.2.4 Pour small quantities
of selected buffer solution into clean beaker.
4.2.5
For accurate calibration use
two beakers for each buffer solution, the first one for rinsing the electrode
and the second one for calibration.
4.2.6
Submerses the electrode and the
temperature probe (3cm) into the sample to be tested buffer solution and stir
the buffer gently. The temperature probe should be close to the pH electrode.
4.2.7
Press CAL CAL ” and
the “7.01” buffer will be displayed on the secondary LCD.
4.2.8 The “6” tag will blink on the LCD until the reading
is stable.
4.2.9 When the reading is
stable and close to the selected buffer (i.e. pH 7), the “READY” tag will be displayed and the “CFM” tag will blink.. Press CFM to confirm calibration.
4.2.10
The calibrated value displayed
on the primary LCD and the second expected buffer value on the secondary LCD.
4.2.11 Rinse the electrode
with distilled water and wipe with soft tissue paper and immersed the pH
electrode and the temperature probe into the second buffer solution and stir
gently.
4.2.12 The “6” tag will
blink on the LCD until the reading is stable.
4.2.13 When the reading is
stable and close to the selected buffer (i.e pH 4) the “READY” tag will be displayed and the “CFM” tag will blink.. Press CFM to confirm calibration.
4.2.14 The calibrated value
displayed on the primary LCD and the second expected buffer value on the
secondary LCD.
4.2.15 After the second calibration point is confirmed, immerse the pH
electrode and the temperature probe into third buffer solution and stir
gently.
4.2.16 The “6” tag will
blink on the LCD until the reading is stable.
4.2.17 When the reading is
stable and close to the selected buffer (i.e pH 9.20) ,the “READY” tag will be displayed and the “CFM” tag will blink.. Press CFM to confirm calibration.
4.2.18 The calibrated value
displayed on the primary LCD and the second expected buffer value on the
secondary LCD.
4.2.19 Then finally rinse the
electrode, finally dip it in sample and record the value.
Notes: If the value measured by the instrument is
not close to the selected buffer, “WRONG”
tags will blink. Check if the correct buffer has been used, or clean the
electrode.
5.0 Calibration Frequency: Daily
6.0Routine maintenance:
6.1 Clean instrument with
dry cloth.
6.2 Clean the electrode
and temperature knob with wet
7.0 Documentation:
7.1 Annexure – 1 - Usage log book XXX/FRM/000
7.2 Annexure
– 2 - Calibration record. XXX/FRM/000
8.0 History of Revision:
Revision No.
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Effective Date
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Revision details
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Reason for revision
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Annexure - 1
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Date
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Booking No.
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Name of sample
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Batch No.
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Used by
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Remark
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SOP No. : XXX/SOP/000 Format No. : XXX/FRM/000-00
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ANNEXURE - 2
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DAILY CALIBRATION DATA
Instrument : pH meter ID :
Make : Model :
Month :
Frequency : Daily
SOP No. : XXX/SOP/000 Format No. : XXX/FRM/000-00
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