Announcing Metrohm's thermometric titration equipment...the Titrotherm.

Thermometric titrimetry gives the analyst another dimension in analytical problem solving, since it employs the most basic property of chemical reactions - namely enthalpy change - to detect the endpoint. Thermometric titrimetry offers the analyst speed, accuracy and precision.

What is a thermometric titration?

Titration is the oldest and most widespread method used in analytical chemistry. For a long time now, potentiometric sensors (indicator electrodes) have been used to cover a wide range of applications in the titration field. As a result, potentiometric titration has become an established analytical method and features in many standards.

The electrochemical potential is only one of the possible ways of following a chemical reaction. A far more universal parameter is the reaction enthalpy. Every chemical reaction is accompanied by a change in enthalpy (ÄH). As long as the reaction takes place, this results in either an increase (exothermal reaction) or decrease (endothermal reaction) in the temperature of the sample solution. For a simple reaction this means that the increase or reduction in temperature depends on the converted amount of substance.

Scope of thermometric titration

Thermometric titration is a very versatile determination method and an ideal complement to potentiometric titration. In principle it is suitable for any reaction that produces a sufficiently large temperature change in the sample solution. It is particularly suitable for applications

• for which no suitable potentiometric sensor is available,
• for which no suitable reference electrode is available,
• in which the sample affects the indicator electrode or destroys it,
• for which no solvent is available that is suitable for potentiometry.

Typical applications of thermometric titration:

Analyte Matrix Titrant

Sulfate Phosphate-containing solutions Ba2+

Phosphate Buffer pH 10 (NH3/NH4Cl) Mg2+

Nickel Ore leachates Dimethylglyoxime

Acid mixtures Electroplating baths (containing HF) NaOH

Advantages of thermometric titration

• Proven method
• Problem solver for difficult samples that cannot be titrated potentiometrically
• Rapid results
• Robust method for routine work
• Well suited for aggressive media

Thermometric sensor advantages

• One sensor for all applications
• Maintenance-free sensor
• No membrane or diaphragm problems
• No sensor calibration required
• Well suited for aggressive media

Thermoprobe - quick, precise and robust

Thermoprobe, a temperature sensor based on semiconductor technology (thermistor), has a short response time of 0.3 s and a high resolution of 10-5 K. This makes the Thermoprobe the ideal sensor for thermometric titration, as it can follow any change in temperature quickly and accurately. The housing made of polypropylene (PP) and epoxy resin provides the sensor with outstanding resistance to many organic solvents and aggressive media.

The software - everything at a glance, everything under control The clearly laid out Titrotherm software allows adaptation of the screen view to the particular method parameters and thus provides rapid access to important commands or parameters. The endpoints are determined by calculating the first and second derivatives of the titration curve; by means of additional optimization parameters, the reproducibility can be improved even further. For report generation, the titration data can be exported manually or automatically into a freely arranged, method-specific report form. For further information please contact Metrohm UK Ltd Tel 01280824824, Fax 01280824800, email cgrantham@metrohm.co.uk