What is Titration?
Titration is a quantitative chemical analysis methoed to determin the unknown concentration of any substance, such as a raw material, substance or finished good. It is a widely used method that has been included in most of the key international pharmacopoeias and other regulations
Volumetric titration is not an absolute method since the result is influenced by the titration equipment, the temperature and other laboratory conditions. It is recommended to determine the titer of volumetric solutions to receive reliable and transparent results. The following points influence the titration results:
- Measuring method
- Instrument (instrument error/abrasion of the burette)
- Electrodes (electrode error/alteration of electrodes)
- Handling (e.g. preparation of dilution)
- Balance (weighing error)
- Change of the volumetric solution because of influence through enviromental oxygen, carbon dioxide, micro organism.
Titration Is Rapid, Reliable, and Accurate.
Merck offers a wide range of innovative reagents and solutions for titration:
- Titripur® complements the product line for volumetric titration, setting new standards for high quality titration with products that conform to the reagents section of the European pharmacopoeia and of the USP
- Merck titration products also include: Aquastar® (a range of products that guarantee a faster, highly accurate Karl Fischer titration), Titriplex® (for complexometric titration), and Titrisol® (a line of concentrates)
- Titripac® provides customers with smart packaging that prevents contamination and allows for a direct connection to the titrator
Titration Reactions and Mediums
|Acid-base titration||Redox titration||Precipitation titration||Complexometric titration|
|Proton transfer Acid ⇌ Base
||Electron transfer Reducing agent ⇌ oxidizing agent
||Sparingly soluble compounds precipitate
||Ions combine with molecules or other ions forming soluble but only slightly dissociated complexes
- Acidimetry ( e.g. hydrochloric acid, sulfuric acid, nitric acid)
- Alkalimetry (e.g. sodium and potassium hydroxide solution)
- Bromatometry (Potassium bromate)
- Cerimetry (Cerium (IV) sulfate)
- Chromatometry (Potassium dichromate)
- Chromometry (Chromium (II) sulfate)
- Iodometry (Potassium triiodide resp. sodium thiosulfate)
- Permanganometry (Potassium permanganate)
- Titanometry (Titanium (II) chloride)
- Ferrometry (Iron(II)-sufate)
- Argentometrie (Silver nitrate)
- Titriplex® III solution (di-sodium EDTA) or Titriplex® IV solution (CDTA)
|Aqueous||Non – Aqueous||Two-Phase Titration|
|Solvent and titrant are aqueous, or one of them contains mainly water
||Solvent and titrant contain practically no water like e.g. organic acids, alcohols, ketones, alkanes, amines
||A suitable non-miscible solvent like e.g. chloroform toluene or dichloromethane is added to the aqueous sample solution
Titration and Quality Assurance According to DIN EN ISO 9001 and DIN EN ISO/IEC 17025
As with all analytical procedures it is also essential with titrimetry to determine results with high accuracy. The method used must be adapted to the problem; suitable working procedures and a reproducible and traceable documentation of results must be present. It cannot be described as a whole how a quality management system for titrimetric analyses must be arranged. The respective circumstances and requirements have to be considered: who titrates what, by which means and with which accuracy? This must be documented in a traceable way. Erroneously quality management is sometimes understood as:
- the request of usability data and additional quality relevant data per certificate from the reagent manufacturer,
- the presentation of technical tolerances of the instrument available from the manufacturer.
These not very expensive activities are, for the following reasons, only a small basis for comprehensive analytical results:
- Usability data of standard solutions, supplied by the manufacturer, are only valid for originally closed containers. After opening other influences play a role.
- The titer indicated on the certificate refers only to the standard solution and is determined independently of the instrument. Specific properties of the analytical instrument used cannot be considered. The indicated titer can directly be applied by the user only with certain limitations.
- Technical data of analytical instruments can only be used in a quality-related way when they are confirmed by regular control. The obvious prerequisite is periodical maintenance and service.