Automatic Titration - Hanna Instruments Hi934 Bedienungsanleitung

3.2. AUTOMATIC TITRATION

Automatic titrators are high-precision analytical instruments that deliver the titrant, monitor the physical change
associated with the titration reaction, automatically stops at the endpoint and calculates the concentration of the
analyte. Automatic titrators are best for repetitive titrations and high-accuracy analyses.
An automatic titrator must have an accurate liquid dispensing system. In high accuracy systems like the HI900-series
titrators, the liquid dispensing system consists of a stepper-motor driven piston syringe burette capable of accurately
and precisely dispensing very small volumes of titrant, a valve system to switch between titrant intake and outlet, and a
dispensing tip. These three main subsystem components must be as accurate as possible, with very low gear backlash in
the burette pump, minimal piston seal flexing, precision ground inner diameter of the glass syringe, a low dead volume
valve, minimal evaporation/permeation, and chemically resistant tubing.
Apparatus required for automatic titration include:
• An automatic titrator, equipped with a burette
• A beaker
• An electronic stirring system, either a propeller stirrer or a magnetic stir bar and stir plate
• Volumetric pipettes for the precise addition of samples
• Standard titrant solutions of known concentration
• An electrode system that can be used to determine the endpoint of the titration
A typical automatic titration consists of the following steps:
1) Set up the automatic titrator according to the manufacturer's instructions.
2) A volumetric pipette is typically used to add a known volume of sample to the beaker.
3) Submerge the propeller stirrer or add the stir bar to the beaker and turn on.
4) Start the titration, the titrator will automatically stop at the endpoint and determine the concentration of the
analyte.
Wrap fingers around tap, keeping
pressure on to stop tap coming out
Swirl flask constantly
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