LaMotte COMBINATION pH ELECTRODE 1904 - Manual (Page 2)

CALIBRATION & MEASUREMENT
Follow the procedure recommended by the pH Meter manufacturer keeping in mind
the Operating Techniques outlined in the previous section. Frequency of calibration
is a function of the electrode, the pH meter and the solutions the electrode is exposed
to. The electrode and meter should always be calibrated together with the calibration
frequency determined by experience. Use two buffers, for example 7 and 4, or 7 and
10. Use the following procedure for both calibration in buffers and for sample
measurements:
1.
Remove the electrode from the soaker bottle. Save the soaker bottle to store the
electrode in after use (see Electrode Storage).
2. Vigorously stir the electrode in a rinse solution. Shake off excess solution.
3. Vigorously stir the electrode in the buffer or sample, and then allow the electrode
to rest in the container.
4. Wait for the reading to stabilize. Record result.
5. Repeat these steps for each sample or buffer determination.
6. Between readings place the electrode in a beaker containing about 2 cm (1 inch)
of pH 4 buffer or distilled water.
ELECTRODE STORAGE
When pH readings are made several days or weeks apart, the electrode should be
stored by replacing it in the soaker bottle, filled with buffer solution.
ELECTRODE CLEANING
Coating of the pH bulb can lead to erroneous readings including shortened span. The
type of coating will determine the cleaning technique. Soft coatings can be removed
by vigorous stirring or by use of a squirt bottle. Organic chemical or hard coatings
should be chemically removed. Only in extreme cases should the bulb be
mechanically cleaned as abrasion can lead to permanent damage.
LaMOTTE COMPANY
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PO Box 329 • Chestertown • Maryland • 21620 • USA
800-344-3100 • 410-778-3100 (Outside U.S.A.) • Fax 410-778-6394
Visit us on the web at www.lamotte.com
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