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To install a membrane:
1. Make sure the top cover(s) are removed from the instrument.
2. Next, unscrew the appropriate enzyme probe retainer and gently pull the probe out of the module.
3. Remove the existing O-ring membrane assembly from the end of the enzyme probe. A lint free tissue or toothpick
or pipet tip may be needed to unseat the old membrane. Be careful not to scratch the enzyme probe face.
4. Examine the enzyme probe surface and remove any pieces of membrane that remained.
5. Open a cavity of the plastic membrane holder.
6. Rinse the membrane inside with a few drops of salt solution (YSI 2392).
7. Place one drop of salt solution on the enzyme probe face.
8. Using the plastic membrane holder, press the O-ring membrane assembly gently onto the probe face.
Figure 4.5
9. Wipe excess salt solution from the probe body.
10. Install a stir bar in the module.
11. Then return the enzyme probe to the module.
12. Finger tighten the probe retainer so that the O-ring seals the probe in place. Do not overtighten.
13. Return the membrane holder to the foil pouch and refrigerate it.
14. Note the expiration date on the membrane package
15. Repeat this procedure for the remaining enzyme probes.
You may want to maintain an instrument log book in which dates and lot numbers of reagents are recorded, along with
information from daily operational checks and other relevant information.
4.9.2 Ion Selective Electrodes
The 2900 Series is shipped without the Ion Selective Electrodes installed in module 3. To install an ISE:
1. First remove the packaging material and the cap from the ISE (save the cap for later use).
2. Slide a black probe retainer over each ISE cable (threaded end first).
3. Slide a white probe sleeve (notched end out) over the end of each ISE.
