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The perfect guide for anybody using electrochemistry and titration. Processing your request Not registered? Karl Fischer Titrants and Reagents Knives. Orbital Shakers Osmometers Ovens.
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Chromatography Solutions. We can help improve your knowledge in key areas such as understanding selectivity and method development. Automatic Potentiometric Titrators 1.
Automatic Titrators, TitroLine® - LLG WWW-Catalog
Historical Development 2. Modern Automatic Titrators 3. Trends 4. Summary References IV.
Other Electrometric Automatic Titrators 1. Amperometric Titrators 2. Conductometric Titrators 3. Thermometric Titrations 4. Summary References V. Automatic Photometric Titrators 1. Photosensitive Devices 2. Photometric Titration Curves 3.
Titrators 4. Summary References VI. Automatic Coulometric Titrators 1. Coulometric Circuits 2. Instruments with Potentiometric Indication 3. Instruments with Amperometric Indication 4.
Instruments with Photometric Indication 5. Multipurpose Coulometric Titrators 6. Sample Selecting Titrators 2. Continuous Titrators 3. Commercially Available Titrators IX. The shape of the titration curve volume of titrant vs. In order to calculate the endpoints precisely the titrant should theoretically be added slowly which means in small steps.
To shorten the time required per analysis, however, the titrant should be added fast which means in big steps. In order to perform the titration fast and precisely, the titrator should thus ideally add the titrant fast until coming close to an endpoint and then slow down the addition of titrant in order to be able to calculate the endpoint precisely. When the curve becomes steeper, the titrant addition should be slowed down.
Adding More Automation and Raising Accuracy in Titration
It is required in any case, however, that the titrant is not added faster than it can react with the sample. This ratio is called control speed C. The evaluation of endpoint must be done according to shape of the titration curve. To filter out endpoints which are not of interest, several approaches are possible as the following two examples illustrate:. Models Meas. This change of the characteristics can be detected either by a so called color indicator or a sensor: A color indicator changes its color as soon as all the substance contained in the sample has reacted with the titrant added.
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- Product Description.
A sensor shows a significant change in the signal measured as soon as all the substance contained in the sample has reacted with the titrant added. Let's have a closer look at some of the main components of a Titrator:. In practice, however, there are other factors which are considerably more important for the accuracy of the burette than the resolution of the drive: Diffusion at the tip of the tube must be prevented by an anti-diffusion device.
Diffusion means titrant addition which cannot be measured by the burette! Worn out piston. The piston of the burette slightly wears off over time and needs to be replaced at regular intervals.
Corrosion of the burette. The burette is made of glass. Some titrants like sodium hydroxide slowly corrode glass which causes a loss of accuracy of the burette. The precision of the burette must thus be checked at regular intervals. Ambient temperature fluctuations.
Titrators measure the volume of titrant added. Accurate results can only be achieved, however, if a certain volume added always represents the same mass. This can be ensured only if the ambient temperature does not fluctuate. The type of sensor to be used depends on the kind of analysis to be performed: Acid base titrations like for example the determination of acidity in fruit juice require a pH electrode as sensor.
Precipitation titrations as for example the determination of table salt NaCl in soy sauce require often a silver electrode. Redox titrations as for example the determination of vitamin C in orange juice normally require a platinum electrode. The determination of certain ions like for example calcium in water require an ion selective electrode.
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