Calibration; Ph Calibration - Oakton pH 5+ Instruction Manual

Instruction Manual pH 5+, pH 6+, Ion 6+

3. CALIBRATION

3.1 pH Calibration

The 5+ and 6+ meter is capable of calibrating up to 5 pH values using the USA or NIST
buffer groups, or 2 pH values using the Low Ionic buffer group. All new calibration
values will automatically override existing calibration data. The non-volatile memory will
retain calibration values upon power shut-off, and battery removal.
For best results, periodic calibration with known accurate standards is recommended.
Calibrate with standards that bracket your intended measuring range while including a
neutral standard (i.e. pH 7.00, 6.86, 6.97). For example, if you expect to measure
samples from pH 6.2 to pH 9.5, calibration using 4.01, 7.00, and 10.01 will work well.
To eliminate temperature errors associated with the pH electrode, attach the automatic
temperature compensation (ATC) probe for best accuracy. Without temperature
compensation, pH accuracy will worsen as samples deviate from 25 ºC and pH 7.
Always rinse electrodes with clean water before and after each calibration or
sample measurement to avoid cross-contamination.
The following calibration standards are automatically recognized;
Buffer Group Available pH Calibration Values
1.68, 4.01, 7.00*, 10.01, 12.45
USA ()
1.68, 4.01, 6.86*, 9.18, 12.45
NIST ()
4.10, 6.97
Pb ()
*These are the only values suitable for a one-point calibration
See Section 3.1—Changing the pH Buffer Group to select a different buffer group.
Always use fresh pH buffer solutions for calibration. Do not reuse buffer solutions as
they change with prolonged exposure to air (especially pH 10 buffer) resulting in
decreased measurement accuracy. Promptly seal containers and store solutions in a
dark, dry, cool environment.
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