YSI pH100A - Manual (Page 7)

5
pH Calibration
The pH100A uses a 2-point calibration. The first point must be a 6.86/7.00 buffer, and the
second either a 4.00/4.01 or 9.18/10.01. These buffers can be purchased from a YSI
representative.
1. Turn the unit on. Connect the pH electrode to the BNC connector and the ATC/Temp
probe to the ATC/Temp connector of the unit; “ATC” displays. Press MODE until “pH”
displays. Autolock may be on or off as desired.
2. Place the pH and ATC/temp probes into the first buffer solution (either 7.00 or 6.86).
Allow temperature readings to stabilize, then press and hold “STAND” for 3 seconds to
calibrate. If AUTOLOCK is off, the first point has been calibrated. If AUTOLOCK is on,
“WAIT” flashes until the unit detects a stable reading. Once the unit calibrates the first
point, “SLOPE” flashes. NOTE: If no temperature probe is connected, adjust the
temperature reading to that of the first buffer using the  or  keys (0.0 to 60ºC) BEFORE
pressing “STAND”.
3. Rinse the pH and ATC/temp probes in distilled water, then place into the second buffer
solution (either 4.01/4.00 or 10.01/9.18). Allow temperature readings to stabilize, then
press “SLOPE” to calibrate. If AUTOLOCK is off, the second point has been calibrated. If
AUTOLOCK is on, “WAIT” flashes until the unit detects a stable reading. Once the unit
calibrates the second point, the unit beeps twice and
both “STAND” and “SLOPE” display
steadily. NOTE: If no temperature probe is connected, adjust the temperature reading to
that of the first buffer using the  or  keys (0.0 to 60ºC) BEFORE pressing “SLOPE”.
4. The unit calculates and compensates for the pH electrode slope deviation corresponding
to the values of the two calibration buffers. The unit is now dual-point calibrated and
ready for measurements. After calibration, press and hold MEA. /EFF. for about 5
seconds to display the new electrode efficiency.
Using the model pH160 Electrode Simulator
The model pH160 Electrode Simulator can be used to confirm proper instrument calibration.
To use the simulator:
1. Install the 9V battery provided.
2. Attach the pH160 to the pH100A. Turn both units on. The pH160 has a small switch to the
right of the pH buttons.
3. In pH measurement mode, press one of the pH buffer simulator buttons on the pH160.
The corresponding pH value should appear on both screens.
Note: Calibration with the pH simulator calibrates only the instrument - NOT the instrument
and probe. For best accuracy, calibrate the pH instrument and probe together using buffer
solutions.
pH Measurements
To take pH measurements, “STAND” and “SLOPE” must display steadily, indicating the unit is
dual-point calibrated and ready for measurements. If “STAND” and “SLOPE” are blinking,
perform a pH calibration before taking measurements.
1. Press
MODE to enter pH mode with AUTOLOCK on or off as desired. For inherently
unstable samples, the unit will not AUTOLOCK. Turn AUTOLOCK off in this case.
2. Rinse the pH electrode and/or ATC/temp probe with distilled water and immerse in the
sample to be measured. Remove any air bubbles trapped around the probe by shaking or
stirring the probe. Allow the pH and/or temperature to stabilize. If no ATC/temp probe is
connected, “MAN” displays, indicating manual temperature compensation. Set unit to
display the sample temperature by pressing the  and  keys (-10.0 to 120°C). If an
ATC/temp probe is connected “ATC” displays along with the sample temperature.
3. If AUTOLOCK is off, the pH value of the sample displays on the screen. If both pH and
temperature readings are stable, take a reading. If AUTOLOCK is on, press MEA./EFF.
“WAIT” flashes until the unit determines a stable pH reading.