Karl Fischer Titration - Mettler Toledo

1 karl Fischer TitrationGTP BrochureGood Titration Practice in karl Fischer Titration EDITORIAL Dear Reader Mettler Toledo has an excellent knowledge in any kind of moisture and water content determination from % to ppm. It is of crucial importance to select the right analytical method in order to obtain reliable results that ensure quality and properties of the products in a multitude of industries. karl Fischer Titration is the method of choice for water content determination. With the new generation of Mettler Toledo compact volumetric and coulometric karl Fischer Titrators V20/V30, C20/C30 and Excellence combined general and volumetric KF titrators T70 and T90, water determination has reached an unrivaled level of simplicity and security.

2 This helps you to perform your daily tasks in the most optimal way. In this brochure a specific focus is put on how to perform the karl Fischer Titration analysis the correct way. We would like to introduce this to you as part of Good Titration PracticeTM (GTP) in karl Fischer Titration . This brochure comprises detailed background information and recommendations about: Chemistry and control of the karl Fischer Titration Practical tips and hints on sample preparation and instrument operation Measures to optimize accuracy and precision of the water determination Selection of the optimal method for water determination of your specific sample Trouble shooting recommendations if results do not coincide with the expectations This GTP brochure in combination with the application brochure 38 should serve you as powerful tools for trouble9free water determination throughout the whole lifetime of your Mettler Toledo KF titrator.

3 We wish you great success and enjoyment Hans9 Joachim Muhr Rolf Rohner Market Support Manager Marketing Manager BA Titration BA Titration Mettler Toledo Good Titration PracticeTM in KF Titration 1 Contents 1 Fundamentals of the karl Fischer Titration .. 4 An historic 4 The karl Fischer chemical 5 Consequences for practical 6 2 Volumetric and Coulometric karl Fischer Analyses .. 7 Volumetric KF reagents .. 7 One9component KF 7 Two9component KF 8 Pyridine9containing 8 Special reagents for aldehydes and 8 karl Fischer reagents with ethanol .. 9 Coulometric KF analysis .. 9 KF 9 Stoichiometry of the coulometric KF rection.

4 10 Iodine generation .. 11 Generator electrode without diaphragm .. 11 Limitations for the use of the cell without diaphragm .. 12 3 Titration control and end point 13 Indication .. 13 Principle of bipotentiometric indication .. 13 End point and polarization 14 Reaction rate .. 16 Stirring speed and dispersion of the volumetric KF titrant .. 16 Control parameters in the volumetric KF Titration .. 18 The Control 18 The minimum and maximum dosing rate .. 19 The Cautious 19 Polarization current and end 19 Application 20 General recommendations .. 21 Control paramaters in the coulometric KF 21 Termination parameters for both coulometric and volumetric KF 22 Using and optimizing the termination parameters for both volumetric and coulometric KF 24 4.

5 The karl Fischer Titration .. 26 The influence of atmospheric humidity (drift determination).. 26 Titration 26 The drift .. 27 Working with the coulometric KF instruments .. 28 Filling the coulometric 28 When do you have to replace the electrolyte? .. 29 Secure draining and filling of the Titration cell: SOLVENT 29 Cleaning the coulometric KF Titration 32 Cleaning the measuring electrode .. 33 Volumetric KF Titration : Titrant 33 How often should the concentration be determined? .. 33 Concentration determination with di9sodium tartrate dihydrate .. 34 Concentration determination with Water Standard mg/g .. 35 Concentration determination with pure 36 The 37 Dissolving capacity of the solvent.

6 38 5 39 Mettler Toledo Good Titration PracticeTM in KF Titration 2 Taking the sample .. 39 Storing the sample .. 39 Amount of sample .. 40 6 Sample addition .. 43 Liquid samples .. 43 Solid 45 7 Release of water from the 47 Internal 48 External 49 External dissolution .. 54 Lyophilized substance in septum bottles .. 55 Determination of water in gases .. 57 Determination using the drying oven .. 58 Principle .. 58 Purge gas .. 58 59 Manual karl Fischer drying oven .. 60 STROMBOLI automatic oven sample changer .. 62 8 Measurement 67 Resolution and detection 67 Measurement accuracy .. 67 Repeatability .. 68 9 Interferences .. 70 Effects of temperature.

7 70 Side reactions .. 70 Reaction with methanol .. 71 Reaction with water .. 71 Reaction with iodine .. 71 Example: reevaluation of side reactions .. 72 10 Troubleshooting .. 73 73 Volumetric karl Fischer 75 11 karl Fischer Titration : The Method at a Glance .. 77 Solid 77 Organic Chemicals .. 77 Inorganic chemicals .. 78 Technical products organic .. 78 Technical products 9 inorganic .. 79 Technical natural 79 Food .. 79 Liquid samples .. 80 Organic and inorganic 80 Foods and technical products .. 81 Titration 83 Volumetric 83 Coulometric 85 Sample preparation and input .. 86 Solids: Characteristics .. 86 Solids: Sample 86 Liquids: 87 Liquids: Sample input.

8 87 Accessories for sample input .. 87 References .. 88 Additional 89 12 Appendix .. 90 Mettler Toledo Good Titration PracticeTM in KF Titration 3 Formula for the external extraction .. 90 Formula for the external 91 Standards for karl Fischer 91 Reagents and solvents for coulometric analysis .. 92 For samples that are soluble in methanol or 92 For samples that are poorely soluble in methanol or ethanol .. 92 For samples that are insoluble in methanol or 93 For ketones and aldehydes .. 93 For acids and bases (pH value) .. 94 Water Standards for karl Fischer volumetric 95 Titrants and solvents for volumetric analysis .. 95 For samples soluble in methanol or 95 For samples poorly soluble in methanol or ethanol.

9 95 For samples insoluble in methanol or 96 For ketones and aldehydes .. 96 For acids and bases (pH value) .. 97 13 Hazards and waste disposal tips .. 98 One9component 98 Two9component reagent:.. 98 Reagents for coulometry: .. 98 Safety data for the KF9components and auxiliary solvents: .. 98 Mettler Toledo Good Titration PracticeTM in KF Titration 4 1 Fundamentals of the karl Fischer Titration An historic overview 1935 Publication: "Neues Verfahren zur massanalytischen Bestimmung des Wassergehaltes von Fl ssigkeiten und festen K rpern" by karl Fischer [1]. 1943 Publication: The Dead9 Stop End Point , by G. Wernimont and Hopkinson [2]. 1950 Pyridine9containing two9component reagents and dead9stop Titration instruments are commercially available.

10 1952 Use of karl Fischer method spreads, promoted by publications by E. Eberius [3]. 1955 Publication on stabilized single9component karl Fischer reagent by E. D. Peters and J. L. Jungnickel. 1956 First German DIN standard for the karl Fischer Titration (DIN 51777, April 1956, Testing of mineral oil hydrocarbons and solvents: Determination of water content according to karl Fischer 9 Direct method ). 1959 Publication: Coulometric karl Fischer Titration by A. S. Meyer and C. [4]. 1960 Automatic KF Titration instruments with piston motorized burettes. Enormous spread of the use of KF Titration . 1970 First coulometric KF Titration instruments are commercially available.