OHS026
Safe Work Procedure
Faculty/Division
Medicine
Document number
Initial Issue date
SOMS.CGM.SWP.040 18-6-09
School/ Divisional Unit
School of Medical Sciences
Oncology Research Unit
Current version
Current Version
1.0
Issue date
18-6-09
Next review date
18-6-12
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: 40_RA_pH Meter_RS
Describe the activity or process
1.
Inspect the pH meter, ensure that the electrical cord is in good condition and that the equipment has been
electrically tested the previous year. 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 525. Please read the SWP on the fume hood before use.
2.
3.
Turn the pH meter on at the power point, and turn the unit on (switch is at back)
Firstly the pH meter needs to be calibrated
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.
4.
5.
Press the ‘Mode” button until pH mode is selected. Rinse the pH probe in distilled water and blot dry.
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.
6.
7.
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.
Rinse the probe in distilled water and blot dry on a clean kim-wipe. 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.
8.
9.
To measure the pH of a solution, ensure that the meter is in pH mode (see Step 4).
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.
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Page 1 of 3
Safe Work Procedure
Date Effective: 01/01/2007
Uncontrolled document when printed
Current Version: 1.2, 15/08/2007
NOTE: To adjust the pH of a solution carefully add (dropwise) either 0.01M NaCl (increases pH of solution) or 0.01M
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.
10. After recording the reading, rinse the probe and blot dry. Store the probe in a saturated KCl solution.
11. Turn off the pH when not in use.
List all resources required including plant,
chemicals, personal protective clothing and
equipment, etc
pH meter
pH calibration 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 when working in the Laboratory.
List potential hazards and risk controls including
specific precautions required
Potential Hazards and exposure to chemicals by the skin, eyes, inhalation and ingestion. To lower this risk, all staff
and students are required to wear full PPE when working in the laboratory. To limit the risk of inhaling the fumes of
10M 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.
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.
Chemical Lists and MSDS are located in the Laboratory as a risk management procedure.
Laboratory induction and regular OHS discussions at Lab Meetings reinforce the potential hazards
List emergency shutdown instructions
In the event of an electrical emergency either turn the pH meter off at the unit/power point or hit the “Laboratory Power
Emergency Shutdown” button.
Please notify the Laboratory Manager (Renee Szokolai x58497) 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 (there MUST be 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.
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Safe Work Procedure
Date Effective: 01/01/2007
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Current Version: 1.2, 15/08/2007
List legislation, standards and codes of practice used
in the development of the SWP
NSW OHS Act 2000
NSW OHS Regulation 2001
AS/NZS 2243.2:2006. Safety in laboratories. Part 2: Chemical aspects
AS/NZS 2243.3-2002. Safety in laboratories. Part 3: Microbiological aspects and containment facilities.
Australian Standard AS2243.7-1991. Safety in laboratories. Part 7: Electrical Aspects
AS/NZS 2161.1:2000 Occupational Protective Gloves – Selection, Use and Maintenance
AS/NZS 1336:1997 Recommended Practices for Occupational Eye Protection
Safe Work Procedure Form (OHS026)
Supervisory approval, training, and review
Supervisor: Edna Hardeman
Signature:
Plant custodian:
Signature
List competency required – qualifications, certificates, licencing, training - eg course or instruction:
Training as per Training Needs Analysis, Induction to lab, Training in this SWP.
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Page 3 of 3
Safe Work Procedure
Date Effective: 01/01/2007
Uncontrolled document when printed
Current Version: 1.2, 15/08/2007