User Manual

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 or select the proper Ion

Charge slope (see SETUP for details, page 40).

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 3512 permits a 5 point calibration in 6 standard solutions

(0.1, 1, 10, 100, 1000, 10000). It is advised to bracket expected ion

concentration with your standards. For fluoride electrode the 2 ppm

standard is also available.

For accurate ISE measurements it is recommended to perform a multipoint

calibration. At least a two-point calibration is required.

Remove the protective cap from the ISE electrode.

SESE

CALIBRATION CALIBRATION

CALIBRATION