* “water” always refers to DI water in this SOP

  1. Startup
  2. Open software

pH Sensor Calibration

  1. Collect
    1. 50 mL or 15 mL centrifuge tube
    2. 3 buffers (4, 7, 10)
    3.  DI water*
    4. tall glass beaker
    5. waste container
  2. Click calibrate pH probe on software
  3. Fill 10-15 mL of 4 pH buffer into centrifuge tube
  4. take pH probe carefully out of rubber sleeve (set sleeve aside)
  5. rinse probe with water into waste container
  6. place probe into centrifuge tube
  7. click start on 4 pH “Buffer 1” line
  8. when done, remove probe from buffer, set aside
  9. dump buffer into waste container
  10. rinse centrifuge tube with several mL of water into waste container
  11. Repeat step from step 3. to 10. for the 7 pH and 10 pH buffers each
  12. Check values on right side of calibration screen.
    1. slope between -56.8 and -61.5 mL/pH
    2. Offset ±30 mL
  13. If values are acceptable, click “adjust.” If not, run a new calibration
  14. When done, put probe back into rubber sleeve. If needed, refill electrolyte liquid in sleeve (0.223 g KCl + 1 mL water)
  15. Discard centrifuge tube into trash

Conductivity Calibration

  1. Collect
    1. 0.1 mol/L KCl mix
    2. centrifuge tube
    3. waste container
    4. centrifuge tube stand
  2. pour ~30 mL of the KCl solution into the centrifuge tube
  3. rinse conductivity probe (white probe) with water into waste beaker
  4. place probe into centrifuge tube, ensuring the hole is fully covered. Add more KCl solution if needed
  5. open conductivity calibration on software, click start
  6. when done, check values and click adjust if within spec
    1. Cell constant: 80-120 m-1
  7. rinse probe with water and return to holder
  8. dump KCl solution into waste container
  9. discard centrifuge tube

Cylindrical cell loading: https://www.youtube.com/watch?v=7qO8TBnxJzw

Adjustable gap cell loading: https://www.youtube.com/watch?v=TgBt0ufIMD0