Hanna Instruments HI 903 - Manual (Page 95)

6-3
TITRATION
6 TITRATION
6.1 Idle
The titrator first enters Idle mode when it is switched on. All of the HI 903’s software features
and adjustable parameters can be accessed from the Idle state. This includes all of the
user-adjustable method parameters, solvent handling system, file transfers, calibration checks,
software upgrades, options for interface with PC and accessories as well as burette options.
To access the titration menu ( Process screen) press .
The titration (Sample Analysis or Titrant Standardization) is performed with the selected method.
Be sure that the selected method is customized in accordance with the specifics of the application.
Before performing a titration make sure that the following conditions are met:
• All of the attached systems (e.g.: solvent system) are properly assembled.
• The right amount of solvent is present in the beaker (between the min and max
marks) for best reproducibility.
The following intermediary stages are performed automatically before starting the analysis:
• Solvent pre-titration
• Drift analysis (Automatic Drift Entry only)
When the drift analysis process is finished, the titrator enters Standby mode. At this point,
a titration can be initiated.
6.2 Pre-titration
In pre-titration the residual water on the interior surface of the titration vessel, the water
contained in the entrapped air and the small amount of water from the solvent is eliminated.
The HI 903 reacts residual water by adding titrant until the specified endpoint potential is
reached. This setting is associated with the active method. After the electrode potential has
stabilized, the titrator moves into the Drift Rate Determination Stage.
When the pre-titration is started, the stirrer is automatically turned on (when
Internal or
External stirrer is selected).