Hanna Instruments HI 902 Color, Quick Start Manual

Page: 76 / 248

5-20
METHODS
5.5.7.3 Filtered Derivatives
This option adds a filtering procedure in the 1
st
and 2
nd
derivative computation algorithm
that reduces the influence of pH or mV noise.
The
Filtered Derivatives
option can be enabled by selecting
YES in the Filtered Derivatives
Option
screen.
Noise can be due to:
• Chemical system properties (sample, titrant, solvent), such as slow chemical reactions
or unbuffered samples such as wastewater, tap water, wine
• Electrode response
• Incorrect method parameters settings such as Signal Stability, Stirring Speed, etc.
• Insufficient titrant additions
Note : A shift in the endpoint volume by 1 or 2 doses may be seen due to filtering.
5.5.8 Pre-Titration Volume
During a titration, the equivalence point is reached after many titrant doses. These doses take
up extra time while having no relevance for equivalence point detection.
Pre-titration volume adds a large initial dose to jump directly to the proximity of the equivalence point.
This first dose occurs after the pre-titration stir time is completed.
The ranges for pre-titration volumes are shown below:
0.001 to 4.500 mL for a 5 mL burette
0.001 to 9.000 mL for a 10 mL burette
0.005 to 22.500 mL for a 25 mL burette
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