Thermo Fisher Scientific C101 Colorimeter - Manual (Page 51)

Calibration: pH
C401/301/101 Colorimeter
47
10. Select another clean vial, un-screw the cap and fill it
with 10 ml of the pH7.0 colorless buffer. (fill up to the
line on the vial).
Note: A proper calibration requires exactly 10 ml volume of pH7.0
buffer.
11. Select a bottle of pH Indicator (Phenol Red). Unscrew
the cap and holding the bottle vertically; gently squeeze
20 drops of Phenol Red into the contents of the vial.
Replace the cap onto the Phenol Red bottle. Be careful
not to over-tighten the cap.
12. Replace the cap onto the vial, ensuring it is screwed on finger tight.
Invert the vial several times to mix.
13. Gently place the vial into the sample well of the instrument, whilst
again aligning the ▼ mark on the vial with the ▲ mark on the meter.
14. Wait for one minute and then press the READ/ENTER key within 3
minutes from when the time the Phenol Red was added to the vial.
15. The meter will display [--Rd--] whilst the calibration standard is being
measured and then displays [SAVE] to prompt for calibration
acceptance and saving of calibration data.
pH
Sample
7.0 pH
pH
READ
ENTER CAL
16. Press the READ/ENTER key. The meter will now accepts the
calibration value and momentarily display [HoLD] and CAL
annunciator before returning to the beginning of the calibration as in
step 3.
17. To continue with another calibration, press the MODE key to select
the desired calibration mode (for multi-parameter colorimeter).
18. To exit the calibration mode, press the ZERO key to return to the
measurement mode.
Press ZERO to
return to
measurement mode
CAL
MODE
READ
ENTER
Press Mode to select
another calibration test
ZERO
CAL
20 Drops
pH
Indicator
Phenol
Red
10 ml
of pH 7.0