25
It is recommended to calibrate the instrument frequently, especially if high
accuracy is required.
The ISE range should be recalibrated:
• Whenever the ISE probe or ion charge is changed.
• At least once a day.
• After testing aggressive chemicals.
• When calibration alarm time out is expired-
“CAL DUE”
warning blinks (if
feature is enabled).
Follow instructions for the individual electrode.
Due to electrode conditioning time, the electrode must be kept immersed a few
seconds to stabilize. The user will be guided step by step during calibration
with easy to follow messages on the LCD. This will make the calibration a simple
and error-free procedure.
PROCEDURE
Select the proper ISE probe in SETUP menu (only for
HI 3222
) or select the
proper Ion Charge slope (see SETUP for details, page 31).
Note:
If the ISE probe has not been previously calibrated (at least one point),
the
“----”
will be displayed.
Pour small quantities of the buffer solutions into clean beakers. If possible, use
plastic beakers to minimize any EMC interferences.
For accurate calibration and to minimize cross-contamination, use two beakers for
each standard solution. One for rinsing the electrode and one for calibration.
The
HI 3221
instrument offers a choice of six standard solutions: 0.1, 1, 10,
100, 1000, 10000 ppm and calibration up to 2 points. The
HI 3222
offers
additional ranges for other concentration units. These cover 5 decades of
concentration. The
HI 3222
permits a 5 point calibration. It is advised to
bracket expected ion concentration with your standards. For fluoride electrode
the 2 ppm standard is also available (
HI 3222
only).
Remove the protective cap from the ISE electrode.
IIIIISE
SE
SE
SE
SE CALIBRATION
CALIBRATION
CALIBRATION
CALIBRATION
CALIBRATION
(HI
(HI
(HI
(HI
(HI 3221 &
3221 &
3221 &
3221 &
3221 & HI
HI
HI
HI
HI 3222
3222
3222
3222
3222)))))