OHS026
Safe Work Procedure
Faculty/Division
School/ Divisional Unit
Medicine
Document number
SOMS_IIR_SWP08
Initial Issue date
18-6-09
School of Medical Sciences
Centre for Infection and Immunity Research
Current version
Current Version
Next review date
1.1
18-6-10
Issue date
18-6-09
The Writing Safe Work Procedures Guideline (OHS027) should be consulted to assist in the completion of this
form.
Safe Work Procedure Title and basic description
Title:
Determining and adjusting the pH of laboratory solutions.
Description: To ensure the safe pHing of solutions in the Laboratory
Associated risk assessment title and location: Wallace Wurth Building C27 - Level 5 Labs Rm 524
Describe the activity or process
Before using the equipment read the instruction manual.
NOTE: If you need to pH with 10M HCL, as opposed to 0.1M HCL, you must carry out this process in the fume
cupboard, located in Rm 524. Please read the SWP on the fume hood before use.
Turn the pH meter on at the power point, and turn the unit on (switch is at back)
Calibrate the pH meter.
NOTE: A “*” in place of the decimal point indicates that the pH readout is not calibrated (full 2-point calibration), or a
past calibration has failed.
Press the ‘Mode” button until pH mode is selected. Rinse the pH probe in distilled water and blot dry with kimwipes.
Place the probe into a small sample of primary buffer (pH 6.88 or pH 7.00) so that the bulb and reference junction are
both covered.
NOTE: DO NOT place the probe directly into the primary buffer bottle as this will contaminate the buffer and reduce its
lifespan. The samples of primary buffer should be changed when the colour of the solution begins to change.
Press the ‘Calibrate’ button to calibrate. The Display will now show an X on the screen, along with the message ‘wait’,
once the reading has stabilised the unit will calibrate itself.
Write the calibration information, including your name and date, in the pH meter book.
Rinse the probe in distilled water and blot dry. Place the probe into a sample of the secondary buffer (pH4.0, 9.23, or
10.01). Repeat Step 6.
NOTE: the ‘*’ in the pH reading will now be replaced by a decimal point if calibration was successful.
To measure the pH of a solution, ensure that the meter is in pH mode.
Rinse the probe in distilled water and blot dry.
Place the probe in the solution to be tested and wait for the reading to stabilise.
Adjust the pH of the solution carefully add (dropwise) either 0.1M NaCl (increases pH of solution) or 0.1M HCl
(decreases pH of solution). This should be preformed while gently stirring the solution (magnetic stirrer) to ensuring
proper mixing of the NaCl or HCl.
After recording the reading, rinse the probe with distilled water and blot dry.
Store the probe in a saturated KCl solution.
Turn off the pH meter when not in use.
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Safe Work Procedure
Uncontrolled document when printed
Date Effective: 01/01/2007
Current Version: 1.2, 15/08/2007
List all resources required including plant,
chemicals, personal protective clothing and
equipment, etc
pH meter
pH buffers (Primary and Secondary)
Distilled water
Kim-wipes
NaCl (0.1M, 1M)
HCl (0.1M, 1M)
Saturated KCl solution
Magnetic stirrer and stirrer bars
Fume cupboard
Always wear long sleeve lab gowns, latex gloves and eye protection working in the Laboratory.
List potential hazards and risk controls including
specific precautions required
Chemical Hazards via skin, eyes, inhalation and ingestion.
To lower this risk, all staff and students are required to wear PPE (long sleeve lab gowns, latex gloves and eye
protection ) when working in the laboratory.
To limit the risk of inhaling the fumes of 1M HCl or NaCl, all staff/students are required to use these solutions in the
fume cupboard.
Prior to working with any chemical reagent/s, staff/students are also required to read the appropriate MSDS’s.
Electrical Hazard such as electric shock.
Inspect the pH meter and ensure that the electrical cord is in good condition and that the equipment has be electrically
tested the previous year.
All staff and students are trained to use the pH meter and have also been orientated in the chemical hazards that exist
in the laboratory by attending a laboratory induction.
Chemical Lists and MSDS are located in the Laboratory as a risk management procedure.
List emergency shutdown instructions
In the event of an electrical emergency either turn the pH meter off at the unit or hit the “Laboratory Power
Emergency Shutdown” button.
Please notify the plant custodian (Katherine Bryant x52785) of any incidents.
List clean up and waste disposal requirements
Make sure the pH meter is turned off after use.
Ensure that the pH probe is placed in the saturated KCL solution. If this solution if running low, please refill the tube
from the stock KCl bottle (need enough to cover the pH bulb and the reference junction). If the KCl stock bottle is
empty, it is YOUR responsibility to make some more up.
List legislation, standards and codes of practice used
in the development of the SWP
NSW OHS Act 2000
NSW OHS Regulation 2001
Australian/New Zealand Standard. 2243.2:2006. Safety in laboratories. Part 2: Chemical aspects
Supervisory approval, training, and review
Supervisor:
Signature:
Plant custodian: Katherine Bryant (x52785)
Signature
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Safe Work Procedure
Uncontrolled document when printed
Date Effective: 01/01/2007
Current Version: 1.2, 15/08/2007
List competency required – qualifications, certificates, licencing, training - eg course or instruction:



UNSW Laboratory Safety Awareness training
UNSW Occupational Health & Safety Awareness training
UNSW Hazardous Substances training

Demonstration of the equipment by the plant custodian or a qualified individual is essential
SWP review date: 18-06-2010
Responsibility for SWP review: Katherine Bryant
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Page 3 of 3
Safe Work Procedure
Uncontrolled document when printed
Date Effective: 01/01/2007
Current Version: 1.2, 15/08/2007