UNIVERSITY OF MALTA
FACULTY OF MEDICINE & SURGERY
PHARMACY DEPARTMENT
Ref. No.
SOP/PD/312_02
STANDARD OPERATING PROCEDURE
®
HANNA BENCH-TOP PH METER HI 8521
Valid for:
2 years from
approval
Table of Contents
Page
1.
2.
3.
4.
5.
6.
7.
8.
9.
Scope
Objective
Definitions
Responsibility
Procedure
5.1. Diagram of Front Panel
5.2. Diagram of Rear Panel
5.3. Installation
5.4. Operation
5.5. Calibration
5.6. Maintenance
5.7.Troubleshooting
5.8.Average time taken to carry out Procedure
5.9. Flow charts
Precautions
References
Appendices
Revision History
Page 1 of 14
2
2
2
3
3
3
3
4
4
5
6
7
8
8
13
13
13
14
UNIVERSITY OF MALTA
FACULTY OF MEDICINE & SURGERY
PHARMACY DEPARTMENT
Ref. No.
SOP/PD/312_02
STANDARD OPERATING PROCEDURE
®
HANNA BENCH-TOP PH METER HI 8521
Valid for:
2 years from
approval
1. Scope
This Standard Operating Procedure (SOP) applies to the staff and students
using the Hanna® Bench-Top pH Meter HI 8521 in the laboratories of the
Pharmacy Department, University of Malta.
2. Objective
To describe the procedure for installation, operation, calibration, maintenance
and troubleshooting of the Hanna® Bench-Top pH Meter HI 8521.
3. Definitions
3.1.
↑ oC and ↓ oC Keys: To set the temperature for Manual Temperature
Compensation.
3.2.
Automatic Temperature Compensation (ATC): A feature in which
the temperature probe is able to detect the temperature of the solution
in which it is immersed in.
3.3.
Bayonet Neill-Concelman (BNC) Electrode connector (1): A cable
connector used to connect the pH or an ORP electrode to the meter.
3.4.
CAL Key: To enter the calibration mode.
3.5.
CON Key: To confirm the calibration data.
3.6.
Display: Digitally displays the pH, temperature and millivolt (mV)
results.
3.7.
DC Power Socket (5): To connect the meter with the mains power
supply.
3.8.
Manual Temperature Compensation (MTC): A feature in which the
temperature of the sample solution is manually inputted when this is
already known.
3.9.
On/Off Key: To turn the meter on or off.
3.10. RANGE Key: To select between pH, millivolt or temperature results.
Page 2 of 14
UNIVERSITY OF MALTA
FACULTY OF MEDICINE & SURGERY
PHARMACY DEPARTMENT
Ref. No.
SOP/PD/312_02
STANDARD OPERATING PROCEDURE
®
HANNA BENCH-TOP PH METER HI 8521
Valid for:
2 years from
approval
3.11. Reference Jack Socket (2): To connect a reference electrode to the
meter.
3.12. Reset Button (3): To be pressed whenever erroneous messages are
displayed due to strong electrical interference or when the meter is
disconnected from its power supply before being switched off properly.
3.13. Temperature Probe Socket (4): The socket at which the temperature
probe is connected to the meter.
4. Responsibility
4.1.
The members of the Department of Pharmacy (staff and students) are
responsible for following this SOP.
4.2.
The designated Laboratory Officer or Laboratory Assistant is
responsible for ensuring that this SOP is followed.
5. Procedure
5.1.
Diagram of Front Panel
5.2.
Diagram of Rear Panel
Page 3 of 14
UNIVERSITY OF MALTA
FACULTY OF MEDICINE & SURGERY
PHARMACY DEPARTMENT
Ref. No.
SOP/PD/312_02
STANDARD OPERATING PROCEDURE
®
HANNA BENCH-TOP PH METER HI 8521
5.3.
Installation
5.3.1.
5.3.2.
5.4.
Valid for:
2 years from
approval
Connect the power cable to the DC Power Socket and to the
mains supply.
Connect the pH electrode and the temperature probe to the
BNC and temperature sockets respectively.
Operation
5.4.1.
Measuring pH
5.4.1.1.
5.4.1.2.
5.4.1.3.
5.4.1.4.
Before use, ensure that the meter is being calibrated,
to obtain more accurate measurements (see section
5.5).
Press the On/Off Key to switch on the meter, which
will automatically enter into pH mode.
Submerge the pH electrode and the temperature
probe into the sample to be tested and keep them
close
together,
if
automatic
temperature
compensation is desired.
Disconnect the temperature probe from the meter if
manual temperature compensation is desired
whenever the temperature of the sample to be tested
is already known.
5.4.1.4.1. Press the RANGE Key until the display
changes to temperature mode.
5.4.1.4.2. Adjust the displayed temperature by
using the Up and Down Keys
respectively.
5.4.1.4.3. Press the RANGE Key again until the
display changes back to pH mode.
5.4.1.4.4. Submerge pH electrode into the sample
to be tested.
5.4.1.5.
5.4.1.6.
Shake the sample briefly and wait for reading to
stabilise before taking the reading.
Read off the displayed stable pH reading
compensated for temperature.
Page 4 of 14
UNIVERSITY OF MALTA
FACULTY OF MEDICINE & SURGERY
PHARMACY DEPARTMENT
Ref. No.
SOP/PD/312_02
STANDARD OPERATING PROCEDURE
®
HANNA BENCH-TOP PH METER HI 8521
5.4.1.7.
5.4.2.
Rinse off the pH electrode with some solution from
the next sample if more than one sample is to be
successively tested.
Measuring Temperature
5.4.2.1.
5.4.2.2.
5.4.2.3.
5.4.2.4.
5.4.2.5.
5.5.
Valid for:
2 years from
approval
Press the On/Off Key to switch on the meter.
Press the RANGE Key until the display changes to
temperature mode.
Dip the temperature probe into the sample.
Allow 1-2 minutes for the reading to stabilise.
Read off the displayed stable temperature reading.
Calibration
5.5.1.
5.5.2.
5.5.3.
5.5.4.
5.5.5.
5.5.6.
5.5.7.
5.5.8.
5.5.9.
5.5.10.
5.5.11.
5.5.12.
5.5.13.
5.5.14.
5.5.15.
Pour small quantities of pH 7.01 and pH 4.01 or pH 10.01
buffer solutions into two separate clean beakers and use another
two separate beakers for rinsing.
Press the On/Off Key to switch on the meter.
Rinse the pH electrode with some pH 7.01 buffer solution.
Immerse the pH electrode into the pH 7.01 buffer solution and
stir gently.
Ensure that the pH electrode is kept submerged approximately
4cm into the solution.
Ensure that the temperature probe is located as close to the pH
electrode as possible.
Press the CAL Key.
Wait until the pH symbol, next to the pH buffer value, stops
flashing to indicate that reading is stable.
Press the CON Key to confirm the calibration.
If [E 4] is flashing, ensure that the correct buffer solution is
being used.
Wait until [E 5] is displayed to indicate that the electrode is still
in the pH 7.01 buffer, but expecting a pH 4.01 or 10.01 buffer.
Rinse the pH electrode with distilled water followed by the
second buffer solution to be used.
Immerse the pH electrode into the second buffer solution (pH
4.01 or pH 10.01) and stir gently.
Wait until the pH symbol, next to the pH buffer value, stops
flashing to indicate that the reading is stable.
Press the CON Key to confirm the calibration.
Page 5 of 14
UNIVERSITY OF MALTA
FACULTY OF MEDICINE & SURGERY
PHARMACY DEPARTMENT
Ref. No.
SOP/PD/312_02
STANDARD OPERATING PROCEDURE
®
HANNA BENCH-TOP PH METER HI 8521
Valid for:
2 years from
approval
5.5.16. If [E 4] is flashing, ensure that the correct buffer solution is
being used.
5.5.17. Wait until the meter returns to the normal operating mode to
ensure that the calibration process was successful.
5.6.
Maintenance
5.6.1.
5.6.2.
5.6.3.
5.6.4.
5.6.5.
5.6.6.
5.6.7.
5.6.8.
5.6.9.
Inspect the cables of the electrodes for any signs of broken
insulation.
Inspect the pH electrode for any cracks in its stem or bulb.
Rinse off any salt desposits with water.
Soak the pH electrode in Hanna HI 7061 or HI 8061 General
Cleaning Solution for approximately ½ hour to perform general
cleaning.
Soak the pH electrode in Hanna HI 7073 or HI 8073 Protein
Cleaning Solution for 15 minutes if protein deposits are present
on the membrane and/or junction of the electrode.
Soak the pH electrode in Hanna HI 7074 or HI 8074 Inorganic
Cleaning Solution for 15 minutes if inorganic deposits are
present on the membrane and/or junction of the electrode.
Rinse the pH electrode with Hanna HI 7077 or HI 8077 Oil and
Fat Cleaning Solution if oil films or deposits are present on the
membrane and/or junction of the electrode.
Rinse the pH electrode thoroughly with distilled water after
performing any of these cleaning procedures.
Refill the reference chamber with fresh electrolyte and soak it
in HI 70300 or HI 80300 Storage Solution for at least 1 hour
before taking any measurements.
Page 6 of 14
UNIVERSITY OF MALTA
FACULTY OF MEDICINE & SURGERY
PHARMACY DEPARTMENT
Ref. No.
SOP/PD/312_02
STANDARD OPERATING PROCEDURE
®
HANNA BENCH-TOP PH METER HI 8521
5.7.
Valid for:
2 years from
approval
Trouble Shooting
Fault
Possible Cause/s
Solution
Meter fails to calibrate or
gives erroneous results
pH electrode is defective
Replace the electrode and repeat the
calibration
-
Meter is slow in responding
or gives erroneous readouts
Electrode not working or
diaphragm is clogged
Meter does not accept 2nd
buffer solution
pH electrode defective or
bad buffer solution
-
-
Reading is drifting
Temperature not stable
-
Display shows [E 1]
pH scale is out of range
-
Temperature scale is out
of range
Display shows [E 2]
-
Display shows [E 3]
Display shows [E 4]
Display shows [E 5]
-
mV scale is out of range
-
Erroneous buffer
solution used for first
part of calibration
Defective electrode
-
Erroneous buffer
solution used for
second part of
calibration
Defective electrode
-
Page 7 of 14
-
-
Leave electrode in storage
solution after performing
diaphragm cleaning
If problem is not solved,
replace electrode and
recalibrate pH scale
Clean the electrode
Replace electrode and
re-calibrate
Use fresh buffer solution
Wait longer since thermal
equilibrium is still not reached
Ensure pH electrode is
connected
Ensure pH of sample is
between 0-14
Check the state of the electrode
and the level of its filling
electrolyte
Ensure T probe is properly
connected
Ensure that T of sample lies
between -10oC and 100oC
Ensure that ORP probe is
properly connected
Ensure mV is within +/- 1999
range
Ensure that buffer solution used
is of pH 7 and replace if
necessary
Replace electrode and
re-calibrate pH scale
Ensure that correct pH buffer
solution is being used (pH 4.01
or pH 10.01)
Check electrode and replace if
necessary
UNIVERSITY OF MALTA
FACULTY OF MEDICINE & SURGERY
PHARMACY DEPARTMENT
Ref. No.
SOP/PD/312_02
STANDARD OPERATING PROCEDURE
®
HANNA BENCH-TOP PH METER HI 8521
5.8.
Average time taken to carry out Procedure
Procedure Section
Average Time (mins)
N/A
Installation
Measuring
pH
with
Automatic 1 (for one pH reading)
Temperature Compensation
Measuring
pH
with
Manual 2 (for one pH reading)
Temperature Compensation
2 (for one T reading)
Measuring Temperature
3 ( for two-point calibration)
Calibration
N/A
Maintenance
N/A
Troubleshooting
5.9.
Valid for:
2 years from
approval
Flow Charts
5.9.1.
Installation
Start
Connect power cable to DC power
socket and to mains supply
Connect pH electrode and T probe to
BNC and T sockets respectively
End
Page 8 of 14
UNIVERSITY OF MALTA
FACULTY OF MEDICINE & SURGERY
PHARMACY DEPARTMENT
Ref. No.
SOP/PD/312_02
STANDARD OPERATING PROCEDURE
Valid for:
2 years from
approval
®
HANNA BENCH-TOP PH METER HI 8521
5.9.2.
Operation
Start
2
No
No
Measuring pH
Measuring T
Yes
Yes
No
Press On/Off key to
switch on meter
Perform calibration before
use (see section 5.8.3)
Meter being
before
calibrated
No
Yes
Display in
T mode
Press On/Off Key
to switch on meter
Yes
No
No
Use ATC feature
Yes
Yes
Submerge pH electrode and T
probe into sample and keep
them close together
Allow 1-2 minutes for
reading to stabilise
Disconnect T probe from meter
Press RANGE Key until display
changes to T mode
1
Shake sample briefly and wait
for reading to stabilise
Adjust displayed T by using the
Up and Down keys respectively
Read off stable pH reading
Press RANGE Key again until
display changes back to pH mode
No
Test another
sample
Submerge pH electrode into
sample to be tested
Yes
Rinse off electrode with next
sample before further use
Dip T probe
MTC
1
2
Page 9 of 14
Read off displayed
stable T reading
End
Press RANGE Key
until display changes
to T mode
UNIVERSITY OF MALTA
FACULTY OF MEDICINE & SURGERY
PHARMACY DEPARTMENT
Ref. No.
SOP/PD/312_02
STANDARD OPERATING PROCEDURE
®
HANNA BENCH-TOP PH METER HI 8521
5.9.3.
Valid for:
2 years from
approval
Calibration
Start
1
Pour small quantities of pH 7.01
and pH 4.01 or pH 10.01 buffer
solutions into 2 separate beakers
Use another 2 separate
beakers for rinsing
Press On/Off Key to
switch on meter
Rinse pH electrode with some
pH 7.01 buffer solution
Immerse pH electrode into
pH 7.01 buffer and stir gently
No
Submerged 4cm
into solution
Submerge accordingly
Yes
Place T probe as close to pH
electrode as possible
No
Meter in pH
mode
Press RANGE Key until display
changes to pH mode
Yes
Press CAL Key
No
No
[E 4] seen
flashing
[pH] symbol
stopped flashing
Yes
Yes
No
Using correct
buffer solution
Press CON Key
Use appropriate
buffer solution
Wait until [E 5] is displayed
Yes
1
Replace electrode
Page 10 of 14
2
Wait until it stops flashing
UNIVERSITY OF MALTA
FACULTY OF MEDICINE & SURGERY
PHARMACY DEPARTMENT
Ref. No.
SOP/PD/312_02
STANDARD OPERATING PROCEDURE
®
HANNA BENCH-TOP PH METER HI 8521
Valid for:
2 years from
approval
2
Rinse pH electrode
with distilled water
Rinse pH electrode with second
buffer solution
Immerse pH electrode into
second buffer and stir gently
No
No
[E 4] seen
flashing
[pH] symbol
stopped flashing
Yes
Yes
No
Using correct
buffer solution
Press CON Key
Use appropriate
buffer solution
Yes
1
Wait until meter returns to
normal operating mode
before further use
Replace electrode
End
1
Page 11 of 14
Wait until it stops flashing
UNIVERSITY OF MALTA
FACULTY OF MEDICINE & SURGERY
PHARMACY DEPARTMENT
Ref. No.
SOP/PD/312_02
STANDARD OPERATING PROCEDURE
®
HANNA BENCH-TOP PH METER HI 8521
5.9.4.
Valid for:
2 years from
approval
Maintenance
Start
Inspect cables of electrodes for any
signs of broken insulation
Inspect pH electrode for any
cracks in stem or bulb
Rinse off any salt deposits with water
No
No
No
Protein deposits
present
General cleaning
Oil films /
deposits present
Yes
Yes
Yes
Soak pH electrode in Hanna HI 7062
or HI 8061 General Cleaning Solution
for ½ hour
Soak pH electrode in Hanna HI 7073
or HI 8073 Protein Cleaning Solution
for 15 minutes
Soak pH electrode in Hanna HI 7074
or HI 8074 Inorganic Cleaning
Solution for 15 minutes
1
1
1
No
Inorganic
deposits present
Yes
Soak pH electrode in Hanna HI 7074
or HI 8074 Inorganic Cleaning
Solution for 15 minutes
1
Rinse pH electrode thoroughly
with distilled water
Refill reference chamber
with fresh electrolyte
Soak in HI 70300 or HI 80300 Storage
Solution for at least 1 hr before use
2
End
Page 12 of 14
2
UNIVERSITY OF MALTA
FACULTY OF MEDICINE & SURGERY
PHARMACY DEPARTMENT
Ref. No.
SOP/PD/312_02
STANDARD OPERATING PROCEDURE
®
HANNA BENCH-TOP PH METER HI 8521
Valid for:
2 years from
approval
6. Precautions
6.1.
6.2.
6.3.
6.4.
6.5.
6.6.
6.7.
6.8.
6.9.
Always keep the pH electrode wet and rinse it thoroughly with the
sample to be measured before use.
In order to measure the pH accurately, the temperature factor must
always be taken into consideration.
If the sample temperature is quite different from the temperature at
which the pH electrode is kept, allow a few minutes for thermal
equilibrium to take place.
When performing a two-point calibration, use pH 7.01 and pH 4.01
when measuring acidic samples and pH 7.01 and pH 10.01 for alkaline
measurements. This provides more accurate readings to be taken.
Do not be alarmed when salt deposits are present on the electrode since
these normally form and can easily be rinsed off with water.
If any air bubbles form inside the glass bulb, “shake it down” firmly to
remove them.
Always store the electrode in its appropriate storage solution and never
store it in distilled or deionised water.
Avoid high humidity environments and static discharges since these are
detrimental for a stable pH reading.
Perform a calibration:
6.9.1.
6.9.2.
6.9.3.
6.9.4.
6.9.5.
6.9.6.
When pH electrode or temperature probe is replaced
When reference electrode is changed
At least once a month
After testing aggressive chemicals
When greater accuracy is required
After any cleaning procedure
7. References
Hanna® Instruments. Instruction Manual HI 8417 – HI 8519 – HI 8520 – HI
8521 Microprocessor Bench-Top pH Meters;1998.
8. Appendices
N/A
Page 13 of 14
UNIVERSITY OF MALTA
FACULTY OF MEDICINE & SURGERY
PHARMACY DEPARTMENT
Ref. No.
SOP/PD/312_02
STANDARD OPERATING PROCEDURE
®
HANNA BENCH-TOP PH METER HI 8521
Valid for:
2 years from
approval
9. Revision History
Version Number
01
02
Page 14 of 14
Amendments/ Reasons for change
Initial Release
Inclusion of subheading titles of
Procedure section in Table of Contents