Calibration; Performing 1-Point Calibration - OHAUS STARTER 3100M Instruction Manual

STARTER 3100M Bench Meter
3.2

Calibration

Standard procedure of pH measurement is as follows:
a) pH electrode preparation
b) buffer preparation and pH electrode calibration
c) sample preparation
d) pH measurement
e) Record measurement results or print
f) Rinse the pH electrode and properly store
pH electrode preparation: pH electrode should be rinsed with pure water before and after use.
Check if the electrode is physically damaged. (Be careful with the glass bulb)
Note: please calibrate the pH electrode before measurement.
STARTER 3100M can perform 1-, 2- or 3- point calibrations.
Calibration: pH electrodes need to be calibrated with pH standard buffer solution before a proper
pH measurement can be made. Calibration is to display the correct pH value when meter receive
the mV value signal from the pH electrode.
Slope: the linear coefficient between mV and pH according to theoretical value (e.g. -
59.16mV/pH @ 25° C which means 100% slope);
Offset: the mV value when pH value is 7.00. (Theoretical value is 0 mV);
3.2.1

Performing 1-point calibration

When performing calibration, Ohaus recommends using Auto End Point Mode. After powering
the meter on, be sure the top of the screen shows
Mode.
Auto or Manual End point Mode:
Press and hold
o
When in Manual Mode, to manually reach a pH measurement or calibration value,
o
you need to press button-
then the sample reading or calibration value freezes,
freezes on the display.
When in Auto End Point Mode, the meter determines when the reading is stable
o
then displays and locks the reading or calibration value automatically, the reading
freezes and
on the display.
Note: With the 1-point calibration only the offset is adjusted. If the sensor was previously
calibrated with multi-point calibration the previously stored slope will remain. Otherwise theoretical
100% slope (-59.16 mV / pH) will be used.
When STARTER 3100M is in pH measurement mode; place the pH electrode in a calibration buffer,
stir 5 seconds, wait for 30 seconds, then:
to change the End Point Mode.
blinks 3 times then disappears;
to ensure the meter is in Auto End point
when reading is stable and displays
blinks 3 times and freezes
EN 11
-
blinks 3 times and
: