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2. Wad a small portion of a lint free tissue and wet it with 70% isopropyl alcohol.
3. Using your thumb, press the alcohol soaked wad against the probe’s surface and rotate the probe back and forth.
4. Rinse the probe with reagent grade water.
5. Install a new membrane on the probe, then install the probe in the sample module.
9.4.3.2 Sensor Cleaning and Reconditioning
The following procedure is recommended to be used only when the enzyme sensor stops operating normally and the
above maintenance procedure is ineffective.
This is not a routine maintenance procedure.
1. With the Membrane removed, immerse the sensor in a 14% solution of ammonia for 3 minutes.
2. Immediately after soaking, rinse the sensor with reagent grade water for 3–5 minutes. It is important that all the
residual ammonia is removed.
3. Prepare a small amount of 0.5% sodium hypochlorite solution.
4. Immerse the sensor in the solution for 30–45 seconds. Check periodically...the sensor should darken, but do not
allow it to become black.
5. Remove the sensor and immediately rinse it with reagent water for at least 2 minutes.
6. Install a new Membrane and return the probe to service.
The procedure below is only recommended as a last resort for revitalizing an enzyme sensor after the above cleaning
procedure has been unsuccessfully attempted.
WARNING: The following procedure may cause permanent damage to the
enzyme sensor.
1. Using a clean new pencil eraser, carefully, rub the center electrode (platinum) of the sensor. Do not rub the epoxy
between the two electrodes or the outer silver electrode.
2. To remove any eraser dust or residual, rinse sensor with 70% isopropyl alcohol and then reagent grade water.
3. Prepare a small amount of 0.5% sodium hypochlorite solution.
4. Immerse the sensor in the solution for 30–45 seconds. Check periodically...the sensor should darken, but do not
allow it to become black.
5. Remove the sensor and immediately rinse it with reagent grade water for at least 2 minutes.
6. Install a new Membrane and return the probe to service.
Note:
Several hours may be required for the sensor to stabilize after cleaning.
9.4.4 ISE Cleaning
Under normal use, it is not necessary to clean the ISE probes. However, if the probes become fouled or contaminated by
the sample composition, they may be cleaned as follows:
1. Soak the ISE with distilled or deionized water for 30 minutes.
2. Recondition the ISE by soaking it in YSI 2970 buffer solution for 4 hours.
9.4.5 Sipper pump Seal Replacement
Replace the Sipper Pump seals every 6 months. Heavy usage may warrant more frequent replacement.
Disconnect the tubing from the Sipper Pump. Remove the two hex screws from the Sipper Pump head and remove it from
the instrument wall (see Figure 9.4).
