Thermo Orion Star, User Manual

Page: 39 / 111

VII-3
Orion Star Series Meter
Thermo Electron Corporation
pH Technique
pH Calibration for 1-5 Points
The calibration points should bracket the expected pH range of the samples to
be measured . Calibration points should be not less than 1 pH unit apart and not
greater than 4 pH units apart .
It is recommended that a two buffer calibration, using buffers that bracket the
expected sample range, be performed at the beginning of each day to determine the
slope and offset of the electrode . This step will also compensate for any changes in
the electrode and determine if it is working properly . For optimal accuracy perform
a one buffer calibration every two hours to compensate for electrode drift using a
fresh aliquot from one of the buffers used in the initial calibration .
Fresh buffers should be used each time you calibrate .
Care should be taken when rinsing the electrode with deionized water and gently
blotting all remaining water drops with a lint-free tissue prior to moving the
electrode to the next beaker .
DO NOT
wipe a glass or epoxy electrode body with a
tissue as static build up will result .
1 . Prepare the electrode for use according to the instructions received with the
electrode .
2 . In setup mode select the buffer set of NIST ( ) or DIN ( ) being used
for the proper buffer recognition to occur .
3 . Press until the arrow icon is pointing to the pH measurement line .
4 . Press .
5 . Rinse the electrode and ATC probe and place into the buffer .