LaMotte DHA 3000 Digital pH Meter - Manual (Page 6)

STANDARDIZING
The DHA-3000 pH meter should be standardized daily, or as operating
conditions are altered during use, for instance if changes occur in the
unknown or temperature. pH buffers should be replaced every three to six
months to assure accurate standardization. If the temperature probe is not
used during standardization, the buffers must be the same temperature as
the sample.
1.
Press button labeled “pH”.
NOTE: If “BAT” appears in the lower left corner, the battery is low
and should be replaced. See Battery Replacement (p. 9) for
instructions.
2. Remove pH electrode from soaker bottle. Rinse pH electrode and
temperature probe with deionized or tap water.
3. Pour a small amount of pH 7.0 Buffer (2881) into a small flask or
beaker. Place pH electrode and temperature probe in beaker. Wait
until display stabilizes.
NOTE: The tip of the pH electrode must be immersed in the buffer
solution.
4. Adjust upper knob labeled “STANDARDIZE” until display reads
7.00.
5. Remove electrode and probe from buffer. Rinse with deionized or tap
water.
6. Select a second buffer based on expected pH to complete
standardization procedure.
NOTE: For solutions with an estimated pH below 7.0 use pH 4.0
Buffer (2866). For solutions with an estimated pH above 7.0 use pH
10.0 Buffer (2896).
7. Pour a small amount of selected buffer into a small flask or beaker.
Place pH electrode and temperature probes in beaker. Wait until
display stabilizes.
NOTE: The tip of the pH electrode must be immersed in the buffer
solution.
8. Adjust lower knob labeled “SLOPE” until pH of selected buffer is
displayed.
9. Repeat Steps 3 through 8 if necessary to check calibration.
10. Remove electrode and probe. Rinse electrode with deionized or tap
water. Place in soaker bottle for storage or proceed to Measuring pH
(p. 7).
11. Discard buffers.
NOTE: Do not disturb these adjustments.
8