Karl-Fischer measurement

Vacuum chamber with tempered shelves 2, container with probe 3, lift for shelves 4, condenser 5, lockgate 6, balance in the lock 7, vacuum pump for the lock 8, glove box 9, Karl-Fischer measuring system 10, pressure controlled vacuum pump 11, manipulator 12, tempered medium (Fig. 1 from [3.30]). 

Given that the introduction of solvent obviously produces wet granules, the wet granulation process includes a drying step. Drying typically occurs in a fluid bed dryer. But there are other options, such as microwave vacuum dryers. In 1994, White applied on-line NIRS to monitor moisture content and predict drying end point in two TK Fielder microwave dryers. The NIR spectral data were correlated to off-line Karl Fischer measurements which resulted in a standard error of prediction equal to 0.6% when the samples... 

Calculate the % mass of water in a portion of anhydrous ether knowing that 1 coulomb is required to attain the equivalence point from 1 ml of ether during Karl Fischer measurements (coulometric version). Recall that two atoms of iodide per molecule of H20 are needed and that the density of ether = 0.78 g/ml. 

Almost all ionic liquids are hygroscopic, even the ones insoluble in water, and they have to be dried carefully before use. The amount of water dissolved in ionic liquids can be determined using Karl-Fischer measurements the most hydrophobic salts, such as [bmim][PF6] and [bmim][NTf2], contain about 1.2% (w/w) of water in their saturated condition. ... 

To remove water, commercial ionic liquids used for fundamental research purposes should be dried at 60 °C in vacuo overnight. The water content should be checked prior to use. This can be done qualitatively by infrared spectroscopy or cyclovoltametric measurements, or quantitatively by Karl-Fischer titration. If the ionic liquids cannot be dried to zero water content for any reason, the water content should always be mentioned in all descriptions and documentation of the experiments to allow proper interpretation of the results obtained. 

In a search for an accurate method of measuring moisture in foods, one cannot overlook the essential requirements of convenience, speed, and precision. Many currently used methods meet these requirements without necessarily yielding accurate results under the conditions used. Probably most important are the electrical methods (IS, 24, 26, 36), the air- and vacuum-oven methods (/, 2, 6, 18, 25, 28, 36), distillation with organic solvents (1, 3, 7, 12, 13, 26, 35), and the Karl Fischer reagent method (9, 11, 26, 31, 32). Without discussing the relative merits of these methods, it can be assumed that accurate results could be obtained with each method by calibration against some accurate reference method. 

A1 from 100%, 9.0 0.5% (6) moisture content by the Karl Fischer method, 0.5% max (7) compressive strength, by pressing to 30000psi with subsequent measurement of pellet diam and height to 0.001 inch, lOOOOpsi min (8) density, by wt and vol measurement, 1.8l4g/cc min ... 

The water content should be and is increasingly determined during RM preparation by Karl Fischer titration. The principle of this method is that it quantifies water selectively by measuring the consumption of iodine. During the titration, iodine oxidizes methylsulfite, formed from methanol and sulfur dioxide in a first step, to methylsulfate under stoichiometric involvement of water. Complete reac-... 

Considering the related Mettler DL 40 and DL 40 RC MemoTitrators, the DL 40 can be used for ten different volumetric and potentiometric methods titration to a pre-selected absolute (EPA) or relative (EPR) end-point equilibrium titration (EQU)-recording titration (REC)-incremental titration (INC) Karl Fischer water determination (KF)-controlled dispensing (DOSE) pH and pX measurements (pX/E) multi-level titrations and back-titrations with automatic calculation (CALC) and manual titration (MAN)-automatic calibration of electrodes (CAL). 

Interpretation of measurements of methods X-ray fluorescence spectrometry (Janssen and van Espen [1986] Arnold et al. [1994]), X-ray diffraction spectra (Adler et al. [1993]), NMR spectra (HIPS, Wehrens et al. [1993a]), HPLC retention indices (RIPS, Wehrens [1994]), Karl Fischer titration (HELGA, Wunsch and Gansen [1989]). 

The produced bio oil was analyzed by GC-MS and Karl Fischer titration. The surface area of the spent catalyst was also measured. Regeneration of the spent catalyst was performed at 450°C for 2h in a muffle oven in the presence of air. The regenerated catalysts were characterized in a similar fashion as the fresh ones. 

Pyrolysis of pine wood biomass was conducted at 400°C followed by catalytic deoxygenation at 450°C. The yield of the different product phases was gravimetrically determined. The gas yield was calculated by the difference. The water content of the bio oil was measured by Karl Fischer titration. The yield of the different product phases is given in Table 3, calculated from the pyrolyzed biomass. The non-catalytic experiment was carried out in the same way as the catalytic ones with the exception that the upper catalyst bed was empty. 

C, shake flask-Karl Fischer titration, measured range 7-51°C, Lane 1946)... 

Thermogravimetry (TG) is a measure of the thermally induced weight loss of a material as a function of the applied temperature [39], Thermogravimetric analysis is restricted to studies involving either a mass gain or loss, and it is most commonly used to study desolvation processes and compound decomposition. Thermogravimetric analysis is a very useful method for the quantitative determination of the total volatile content of a solid, and it can be used as an adjunct to Karl Fischer titrations for the determination of moisture. 

The amount of water present is fundamental to the stability of confectionery products. Unsurprisingly, therefore, measuring water content is an important exercise. Various methods are used. Some oven drying moisture content determinations are still carried out. This sort of work is difficult since the moisture contents are normally low and the samples can only be dried with difficulty. In particular, there are problems in drying the product in a reasonable time without charring it. Various other methods of water content determination are in use. One such is the Karl Fischer titration. 

Fig. 1.97.1. Schema of the Coulometer MeBzelle DL 36 for measurement of residual moisture content (RM) after Karl Fischer. In the titration cell (1) iodine is electrolytically produced (3) from an iodine-containing analyt (2). Water in the titration cell reacts with the iodine. When the water is used up, a small excess of iodine is produced, which is detected by special electrodes, which leads to iodine production being stopped. The amount of water in the cell can be calculated from the reading of the coulometer, and the amount of electrical charge needed. The solids are introduced into the cell either by a lock, or the water is desorbed in an oven and carried by a gas stream into the cell. 10 pg in a sample can be detected with an accuracy of reading of 0.1 pg (KF Coulometer DL36, Mettler-Toledo AG, CH-8603 Schwerzenbach, Switzerland).

After 66 h, the pressure control could no longer maintain the selected pressure of 0.048 mbar thus, the pressure control is cut off, the pressure drops to 0.012 mbar (CA). The RM measurement by Karl Fischer showed 0.8 0.06 %. 

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. 

An important source of error in nonaqueous conductance measurements is the presence of water in the system. As little as 1 X 10 "4 M water (2mg/l) may cause errors in many solvents. The difficulties faced in maintaining anhydrous conditions are formidable. Closed cell systems for handling solvents and salts have been described earlier. The most widely used method for measuring the water content of a solvent at low levels is still the Karl Fischer titration. 

IL. Dilute solution viscosity measurements were done at 30 with the appropriate Ostwald-Fenske capillary viscometers. The water content of all organic solvents, used as the liquid phase in solid-liquid PTC runs was analyzed by potentiometric Karl Fischer titration using a Metrohm AG CH 9100 model automatic titrator. 

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 Titrators These titrators measure moisture (water) in a variety of samples. The titrant s concentration is usually expressed as titer, or grams of water consumed per milliliter of titrant. Standardization involves a certified primary standard (a material containing a known amount of water). This standard is purchased in ampules and is accompanied by a test certificate indicating traceability to a reference material. In addition, the titrator should be calibrated for the titrant volume measurement. The moisture can be measued by weight loss upon drying and checked against the Karl Fischer results. 

Water can be identified from its physical properties. Also, trace amounts of water may be determined by Karl-Fischer analysis. The Karl-Fisher reagent is a solution of iodine, sulfur dioxide and pyridine in methanol or methyl cel-losolve. Water of crystallization in hydrates can be measured by TGA and DTA methods. The presence of trace moisture in gases can be determined by mass spectrometry. The characteristic mass ion is 18. 

Figure 3.21 illustrates an application of FIA to the Karl Fischer titration. The consumption of the reagent by water is detected spectrophotometrically by monitoring the stream of reagent at 615 nm. The absorbance due to the iodine in the reagent is removed by its reaction with water, which causes formation of iodide and thus negative absorbance is measured. 

The absolute methods (meaning no independent calibration is necessary) for determining H20t include manometry (Newman et al., 1986), Karl-Fischer titration (Behrens et al., 1996), and nuclear reaction analyses (NRA). NRA is a bulk method for H20t and requires a density estimate to convert data to weight percent. Secondary ion mass spectrometry (SIMS) can measure H20t, but it requires... 

Analyses of Water Content. The water content of the PIQ starting materials was analyzed. The water content of amines was measured using a DuPont 321A moisture meter and those of the solvents were measured by Karl Fischer s reagent method. The water content of acid dianhydrides was measured by titrating the free acid. 

The water content in the starting materials was measured as follows. The water content of amines and solvents were measured using the DuPont 321A moisture meter and Karl Fischer s reagent methods, respectively. Since the water contained in acid dianhydride is considered to convert it to free acid. 

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