Titration, a common laboratory method of quantitative chemical analysis used to determine the unknown concentration of a known reactant, is today usually performed by a dedicated titrator. Different types of titrators are available depending on the specific analysis required. The first consideration when purchasing a laboratory titrator is to decide what type of analysis is required.
Most titrators offer one type of analysis, whether it is Karl Fischer, potentiometric or another type. These titrators are suitable for most purposes in which the same types of analyses are performed multiple times.
A. Karl Fischer
Karl Fischer titration is a classic titration method in analytical chemistry used to determine trace amounts of water in a sample. it can be used for determining the water content in fluids, solids, pasty substances, oils and gases. Karl Fischer titration can use either a coulometric or volumetric technique and is highly accurate with a high selectivity for water.
1. Volumetric
In volumetric Karl Fischer titration, the titrant is added directly to the sample via a burette. The moisture content of the sample is determined from the titration volume.
- Compact titrator: In situations where space is limited, a compact titrator can be the ideal choice.
- Standard titrator: Standard titrators tend to have greater functionality and sample capacity than compact versions and may be more appropriate when space is not an issue.
- Mono burette: Titrators with a single burette are adequate for many standard laboratory applications.
- >1 burette: More than one burette may be useful for certain analyses (back titration, for example) or when rapid turnover is required.
2. Coulometric
In coulometric Karl Fischer titration, the titrant is generated electrochemically in the titration cell. The coulometric method measures water levels much lower than the volumetric method.
- Compact titrator: In situations where space is limited, a compact titrator can be the ideal choice.
- Standard titrator: Standard titrators tend to have greater functionality and sample capacity than compact versions and may be more appropriate when space is not an issue.
3. Volumetric and coulometric
If both volumetric and coulometric titrations are required on a regular basis, the preferred option may be to select a single titrator that can operate in both modes.
B. Potentiometric
In a potentiometric titration, no indicator is used. Instead, the voltage across the analyte (typically an electrolyte solution) is measured.
- Mono burette: Titrators with a single burette are adequate for many standard laboratory applications.
- Bi burette: more than one burette may be useful for certain analyses (back titration, for example) or when rapid turnover is required.
C. Stat titration
pH-stat titration is applicable to any bioreaction involving pH variations. The main application of pH-stat titration has traditionally been nitrification monitoring, however it may also be used to monitor any reaction involving the production or consumption of protons, hydroxyl ions, or inorganic carbon chemical species.
- Mono burette: Titrators with a single burette are adequate for many standard laboratory applications.
- Bi burette: more than one burette may be useful for certain analyses (back titration, for example) or when rapid turnover is required.
D. Acid/base
The acidity or alkalinity of a solution may be determined using a classic acid/base titration.
- Acidity: Some titrators are designed specifically to measure acidity.
- Compact titrator: In situations where space is limited, a compact titrator can be the ideal choice.
- Standard titrator: Standard titrators tend to have greater functionality and sample capacity than compact versions and may be more appropriate when space is not an issue.
- Alkalinity: Some titrators are designed specifically to measure alkalinity.
- Alkalinity and acidity: Some titrators are designed to measure both acidity and alkalinity.
E. Other modes
Titrators can also be designed to analyze single elements such as sulfur or chlorine.
In some circumstances, particularly where different types of analyses are required from time to time and no single analysis is performed routinely, a combined titrator may be the ideal solution.
A. Potentiometric plus KF
Some titrators are equipped to perform both potentiometric and Karl Fischer titrations.
B. Conductivity plus potentiometric
Some titrators are equipped to perform both potentiometric and conductivity titrations.
Titrators used in the analysis of food and drink, for example, may be required to analyze a whole range of factors including chloride, acid and water content. These titrators can be considered 'multi-parameter' systems.
A. Compact
In situations where space is limited, a compact titrator can be the ideal choice.
B. Standard
Standard titrators tend to have greater functionality and sample capacity than compact versions and may be more appropriate when space is not an issue.
- Karl Fischer option: Some multiparameters also include the option for KF titration, either through an integral unit or through an optional add-on.
- No Karl Fischer option
- Specifically for food and drink analysis: Some titrators are specially designed to include the parameters required for the analysis of food and drink, including wine; for example, analysis of salt, water, acid and fat.
- Comprehensive analysis (excluding KF): Some titrators include a full range of sophisticated analyses including any combination of titration and ion analysis, conductivity analysis, turbidity analysis, color analysis and spectrophotometric analysis for a fully comprehensive system.