Ph Calibration Procedure - Thermo Scientific Orion Star A220 Series User Manual

Thermo Scientific

pH Calibration Procedure

Orion Star A221 pH meters can perform a pH calibration using one to five pH buffers with easy
to follow onscreen instructions to assist with the calibration process.
Always use fresh pH buffers and select buffers that bracket the sample pH and are one to three
pH units apart. Prepare the pH electrode according to the instructions in the electrode manual.
Connect all electrodes to be used to the appropriate meter inputs.
Make sure the meter measurement mode is set to pH.
1. Press the f1 (cal) key to start the calibration.
2. Rinse the pH electrode and any other electrodes in use with distilled water, blot gently with
a lint-free tissue to remove excess water and place into the pH buffer.
3. When the electrode and buffer are ready, press the f3 (start) key.
4. Wait for the pH value on the meter to stabilize and perform one of the following actions:
a. Press the f2 (accept) key to accept the pH buffer value determined by the automatic
buffer recognition function.
or
b. Press the f3 (edit) key to access the popup number entry screen and manually enter
the pH buffer value.
i. Press the p, q, t or u key to highlight a number or decimal point, press the
f3 (enter) key to select the highlighted item and repeat until the desired value is
shown at the top of the screen.
ii. Press the f2 (done) key to save the value and exit the number entry screen.
iii. Press the f2 (accept) key to accept the manually entered value.
5. Press the f2 (next) key to proceed to the next pH buffer and repeat steps 2 through 4 or
press the f3 (cal done) key to save and end the calibration. If five buffers are used, the
calibration will save and end once the fifth value is accepted.
a. When performing a one point calibration, press the f2 (accept) key to accept the
displayed slope value or press the f3 (edit) key, use the popup number entry screen to
enter a new slope value, press the f2 (done) key and then press the f2 (accept) key.
6. The meter will display the calibration summary including the slope and export the data to
the calibration log. Press the f1 (meas) key to proceed to the measurement mode or press
the f2 (print) key to export the calibration data to a printer or computer.
Chapter 4
Orion Star A220 Series Portable Meter User Manual
Using the pH Channel
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