horiba LAQUA 2000 Series, Инструкция по эксплуатации

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Ion Calibration
15
● Ion Calibration
Calibration is necessary for accurate ion measurement. To perform ion calibration using
ION2000 or PC2000 meter, follow the procedure detailed below:
Prerequisites
• If ion electrode is new or stored for long period, condition it first. Refer to the ion electrode
manual for the electrode preparation and conditioning procedures.
• Clean the ion electrode with DI (deionized) water and wipe it with tissue paper.
• Switch on the meter and plug in the ion electrode.
• Ensure that the meter is in ion measurement mode.
• Select the ion electrode in use (or set the ion valence) and concentration unit of standard
solutions in ion setup mode.
• Prepare standard solutions required for calibration. Refer to the ion electrode manual for
the standard solution preparation procedure.
• Dip the ion electrode into the standard solution ensuring that the solution level is at least 3
cm from the electrode tip.
• For calibration, prepare at least 2 standards solutions with ionic strength adjustor that are
ten-fold apart in concentration.
• Standard solutions should bracket the expected ion concentration in the sample.
• For setting the ion concentration unit, refer to “P1.1 Ion Concentration Unit Setup” on
page 34. Three units are available: µg/L ↔ mg/L ↔ g/L , ppm ↔ ppt , and
mmol/L ↔ mol/L .
• For selecting the ion electrode type or setting the valence of the ion to be measured, refer
to “P1.2 Ion Electrode Type Setup” on page 35. Seven ion electrode types are available:
NH3 (Ammonia), CL (Chloride), FL (Fluoride), NO3 (Nitrate), POT (Potassium),
CA (Calcium) and CUST (Custom).
• Select CUST and then the correct ion valence (-2, -1, 1, 2), if the ion electrode in use is not
in the selection of ion electrode types. Ion valence is CHRG in the meter, which stands for
“charge”.
• Ion concentration varies depending on the sample temperature. For accurate
measurement, it is recommended that the calibration and measurement are carried out at
a constant temperature (e.g., using a constant temperature bath). Stir the standard
solutions and samples using a stirrer during calibration and measurement.
• Because the ion electrode is not equipped with a temperature sensor, the temperature
electrode must be connected in order to use the automatic temperature compensation
(ATC). In ATC mode, the Nernst slope (mV/one decade) is automatically changed
corresponding to the measured temperature by the temperature sensor. If the ATC function
is not used, match the temperature setting of the instrument to the temperature of the
standard solutions during calibration and match the sample temperature to the temperature
setting of the instrument in measurement. By doing so, you can obtain the correct
measurement value without being affected by sensitivity variation caused by temperature.
Note