Water with Karl Fischer reagent

Wash solutions for precipitates, 426 Washing of precipitates 118, 426 by decantation. 119 solubility losses in, 119, 427 Washing soda D. of sodium carbonate in, 295 Water absorbents for, 477 ammonia-free, 679 deionised, 90 D. of hardness, 332 D. of total cation concentration, 210 D. with Karl Fischer reagent 637 distilled, 90 high purity, 91 ionic product of, 36 types and standards for, (T) 90 volume of 1 g at various temperatures, (T)87... 

It refers to the determination of water content titrimetrically with Karl Fischer Reagent (KFR). This technique has been used exclusively for the determination of water content in a number of pharmaceutical substances listed below (see Part II G, Chapter 14) ... 

Flow would you explain the presence of water in an anlyte usually reacts with Karl Fischer reagent in a two-stage process Give the chemical reactions involved in the above procedure. 

Microdetermination of Water by Titration with Karl Fischer Reagent is described by Pierson (Ref 11, pp436-38)... 

R. G. Bennett, et. al.. Determination of external water in white sugars by direct titration with Karl Fischer reagent, Int. Sugar J. 66, 109-113 (1964). 

Eberius, Water Determination with Karl Fischer Reagent, 2nd edition, Weinheim, 1958. 

The moisture content of seeds has been determined (Hart et al., 1962) by near-infrared spectrophotometry of their methanol extracts. The absorbance of water at 1.93 fi was used. The standard deviation of the results from those obtained by titration with Karl Fischer reagent was +0.24%. The infrared method was more rapid and less exacting than the Karl Fischer method. 

Karl Fischer titration is specified for use in plasticizers. The method determines free and Itydration water in solid and liquid samples. In most cases, automatic titration is used and this is the main subject of standard but manual titration method is also included in the appendix. The sample containing a maximum of 100 mg of water is dissolved in a suitable solvent and titrated with Karl Fischer reagent which consists of iodine, sulfur dioxide, organic base, and solvent. The titration end-point is determined amperometrically. The ASTM method lists numerous substances in which the presence of water can be determined. There is also a list of substances which interfere with measurements. 

A method reported for the measurement of water strongly held by (hen egg-white) lysozyme was based on vacuum drying and titration with Karl Fischer reagent. Investigations were conducted over the temperature range — 20 °C—h 20 °C. The 23 or 20 water molecules held per lysozyme molecule fell into several classes. Three to four of them were quite strongly held and may correspond to the three buried water molecules observed during AT-ray... 

Karl Fischer Reagent Ethylene Glycol Monomethyl Ether Solution, stabilized, containing pyridine, (1 mL = S mg of water)—Fresh Karl Fischer reagent must be used. Must be used with solvent in 7.6.1. 

Karl Fischer reagent A mixture ofU and SO2 dissolved in pyridine - MeOH used as a titrant for water with which HI is liberated and the pH determined with a meter. 

Another important example of a redox titration for inorganic analytes, which is important in industrial labs, is the determination of water in nonaqueous solvents. The titrant for this analysis is known as the Karl Fischer reagent and consists of a mixture of iodine, sulfur dioxide, pyridine, and methanol. The concentration of pyridine is sufficiently large so that b and SO2 are complexed with the pyridine (py) as py b and py SO2. When added to a sample containing water, b is reduced to U, and SO2 is oxidized to SO3. 

Methanol is included to prevent the further reaction of py SO3 with water. The titration s end point is signaled when the solution changes from the yellow color of the products to the brown color of the Karl Fischer reagent. 

DETERMINATION OF WATER WITH THE KARL FISCHER REAGENT 16.35... 

Compounds which can be regarded as forming water with the components of the Karl Fischer reagent, for example ... 

The Karl Fischer procedure was applied to the determination of water present in hydrated salts or adsorbed on the surface of solids. The procedure, where applicable, was more rapid and direct than the commonly used drying process. A sample of the finely powdered solid, containing 5-10 millimoles (90-180 mg) of water, was dissolved or suspended in 25 mL of dry methanol in a 250-mL glass-stoppered graduated flask. The mixture was titrated with standard Karl Fischer reagent to the usual electrometric end point. A blank titration was also carried out on a 25 mL sample of the methanol used to determine what correction (if any) needed to be applied to the titre obtained with the salt. 

Karl Fischer titration. This titration procedure determines the concentration of water present in AOS samples containing 40-70 wt % water. In Karl Fischer titrations, each equivalent of base interferes as 18 g of water. Since AOS samples are basic, water values obtained must be corrected for side reactions of reagent with alkaline material. Alkalinity must be determined to correct for this error. 

Bottles containing a modified Karl Fischer reagent with formamide replacing methanol developed gas pressure during several months and burst. No reason was apparent, but slow formation of sulfuric acid, either by absorption of external water or by... 

Conditioning the solvent means to eliminate all water in the solvent by titrating it with the Karl Fischer reagent. This is done to keep from measuring this water rather than the water in the sample. 

Karl Fischer reagent analy chem A solution of 8 moles pyridine to 2 moles sulfur dioxide, with the addition of about 15 moles methanol and then 1 mole iodine used to determine trace quantities of water by titration. karl fish-or re a-jont Karl Fischer technique analy chem A method of determining trace quantities of water by titration the Karl Fischer reagent is added in small increments to a glass flask containing the sample until the color changes from yellow to brown or a change in potential is observed at the end point. karl fish-or tek nek kauri-butanol value analychem The measure of milliliters of paint or varnish petroleum thinner needed to cause cloudiness in a solution of kauri gum in butyl alcohol. kail-re byut-3n,ol, val-yu ... 

Karl Fischer reagent reacts immediately and quantitatively with water, accdg to the equation derived in 1939 hy Smith, Bryant Mitchell and later described by R.W. Freedman in AnalChem 28, 247(1956) ... 

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