* “water” always refers to DI water in this SOP
- Startup
- Open software
pH Sensor Calibration
- Collect
- 50 mL or 15 mL centrifuge tube
- 3 buffers (4, 7, 10)
- DI water*
- tall glass beaker
- waste container
- Click calibrate pH probe on software
- Fill 10-15 mL of 4 pH buffer into centrifuge tube
- take pH probe carefully out of rubber sleeve (set sleeve aside)
- rinse probe with water into waste container
- place probe into centrifuge tube
- click start on 4 pH “Buffer 1” line
- when done, remove probe from buffer, set aside
- dump buffer into waste container
- rinse centrifuge tube with several mL of water into waste container
- Repeat step from step 3. to 10. for the 7 pH and 10 pH buffers each
- Check values on right side of calibration screen.
- slope between -56.8 and -61.5 mL/pH
- Offset ±30 mL
- If values are acceptable, click “adjust.” If not, run a new calibration
- When done, put probe back into rubber sleeve. If needed, refill electrolyte liquid in sleeve (0.223 g KCl + 1 mL water)
- Discard centrifuge tube into trash
Conductivity Calibration
- Collect
- 0.1 mol/L KCl mix
- centrifuge tube
- waste container
- centrifuge tube stand
- pour ~30 mL of the KCl solution into the centrifuge tube
- rinse conductivity probe (white probe) with water into waste beaker
- place probe into centrifuge tube, ensuring the hole is fully covered. Add more KCl solution if needed
- open conductivity calibration on software, click start
- when done, check values and click adjust if within spec
- Cell constant: 80-120 m-1
- rinse probe with water and return to holder
- dump KCl solution into waste container
- discard centrifuge tube
Cylindrical cell loading: https://www.youtube.com/watch?v=7qO8TBnxJzw
Adjustable gap cell loading: https://www.youtube.com/watch?v=TgBt0ufIMD0