Water Determination Karl Fischer Titrimetric Method

Assay and test results are determined on the basis of comparison of the test sample with the reference standard that has been freed from or corrected for volatile residues or water content as instructed on the reference standard label. If a reference standard is required to be dried before use, transfer a sufficient amount to a clean, dry vessel. Do not use the original container as the drying vessel, and do not dry a reference standard repeatedly at temperatures above 25°. Where the titrimetric determination of water is required at the time a reference standard is to be used, proceed as directed in the Karl Fischer Titrimetric Method under Water Determination, Appendix IIB. 

Water and Loss on Drying In general, for compounds containing water of crystallization or adsorbed water, a limit test, to be determined by the Karl Fischer Titrimetric Method, is provided under the heading Water. For compounds in which the loss on drying may not necessarily be attributable to water, a limit test, to be determined by other methods, is provided under the heading Loss on Drying. 

Water Determine as directed in the Karl Fischer Titrimetric Method under Water Determination, Appendix IIB, using methanol in pyridine (1 2) as the solvent. 

Water Determine as directed for Method la in the Karl Fischer Titrimetric Method under Water Determination, Appendix IIB, using a 100-g sample melted on a hot plate at 60°. Use a syringe to apply the oil to the Karl Fisher titrimetric apparatus (usually 1.0 mL is sufficient, but this may vary depending on the water content of the sample). 

Water Determine as directed for Method lb (Residual Titration) in Method I (Karl Fischer Titrimetric Method) under Water Determination, Appendix I IB. 

Water Proceed as directed under Water Determination using the Karl Fischer Titrimetric Method, Appendix KB. However, in place of 35 to 40 mL of methanol, use 50 mL of a 1 1 chloro-formmethanol mixture to dissolve the sample. 

Water Determine as directed under the Karl Fischer Titrimetric Method, Appendix KB. 

Measurement of the water content of a wide variety of materials is a problem of universal interest a review of physical and chemical methods for its measurement has been made. Though we are concerned here only with the Karl Fischer titrimetric method, it should be mentioned that gas-chromatographic methods for the determination of traces of water in small samples would seem to be an attractive alternative. ... 

Several physical and chemical procedures have been elaborated for the determination of small amounts of water in solvents [Ha 72, Mi 61], but in most cases the Karl Fischer titrimetric method [Fi 35] has proved the most suitable. The essence of the method is that, in methanolic solution containing pyridine as proton binder, the reaction between sulphur dioxide and iodine in the presence of water takes place quantitatively in accordance with the equation... 

Chromatograms for determination of small amounts of water in several aldehydes are shown in Fig. 8.6. This same two-column method is also useful for other difficult samples. For example, peroxides are highly oxidizing and interfere with the Karl Fischer titrimetric determination of water. Water has been determined by the chromatographic method in several organic peroxides [17]. 

In industry and commerce, one of the most widely used analytical methods is the Karl Fischer titration procedure for the determination of water in various types of solids and organic liquids. This important titrimetric method is based on an oxida-tion/reduction that is relatively specific for water. ... 

Recent applications have shown the potential of flow titration as a modem tool in analytical chemistry. As the required amount of titrand is associated with the analytical signal, important parameters, e.g., oxidis-ability in wastewaters [339], bromine number in foodstuffs [340], bitterness of beers and similar [341], total acidity in wines and vinegars [342] and total alkalinity in natural waters [343], are efficiently determined. In addition, the total concentration of several analytes belonging to the same family, e.g., amines [344], can be determined. The entire titration curve is generally available, allowing the determination of weak acids, complex stability constants and acid dissociation constants [345]. The determination of humidity by the Karl Fischer method [346] is another important application of flow titrations. For single analyte determinations, the analytical characteristics inherent to titrimetric procedures, such as enhanced accuracy and precision, should be emphasised. 

Determination of residual water on paracetamol crystallized in water according to the titrimetric direct method of Karl Fischer. 

Determination of residual water was carried out using Karl Fischer s titrimetric direct method after calibration with natrium tartrate and dissolution of ibuprofen or meprobamate crystals in methanol. 

The titrimetric determination of water by the Karl Fischer method depends on the reaction that takes place quantitatively between water and a reagent consisting of sulfur dioxide and iodine in anhydrous pyridine and methanol. The reaction is carried out in methanol. 

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