VWR pH110 Manual Del Usuario página 7

OPERATIONAL PROCEDURES
Buffer Table Select
This unit has two buffer sets: 7.00,4.01,10.01pH and 6.86,4.00,9.18pH. To change the buffer
set, turn off the unit, then press and hold STAND while turning on the unit again. If the unit is
uncalibrated and in pH mode, it displays "7.00" if the first set is active, and "6.86" if the second
set is active.
pH Calibration
The pH110 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 VWR 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.
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.
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