Karl Fischer analyzers

The n-butanol (99.7 mole% stated purity) was from Malinckrodt, and n-butoxyethanol (99+ % stated purity) was from Aldrich. Each was analyzed by gas chromatography for impurities and by Karl Fischer titration for water, and used without further purification. The water was distilled. 

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. 

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. 

Baker Analyzed dimethylsulfoxide, which is freshly opened and dry to Karl Fischer reagent, is used without further purification. 

Ammonium chloride is analyzed by treatment with formaldehyde (neutralized with NaOH) and the product HCl formed is analyzed by titration using an acid-base color indicator such as phenolphthalein. Alternatively, it may be mixed with caustic soda solution and distdled. The distillate may be analyzed for NH3 by titration with H2SO4 or by colorimetric Nesslerization or with an ammonia-selective electrode (APHA, AWWA, WEF. 1995. Standard Methods for the Examination of Water and Wastewater. 19th ed. Washington, DC, American Pubhc Health Association). The presence of ammonia or any other ammonium compound would interfere in the test. The moisture content in NH4CI may be determined by Karl—Fischer method. 

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. 

Run the standard process with 100% loading rate. Collect the dried stoppers in predried glass vessels. The stoppers are afterward cut into pieces of 80 mg and analyzed using the Karl Fischer moisture determination method. The moisture out of the stoppers is obtained at increased temperature and blown over with nitrogen into the reaction vessel. 

All enthalpy of solution measurements were carried out with an LKB 8700-1 precision calorimetry system. The experimental procedure and tests of the calorimeter have been reported previously (3, 4, 5). The purification of the solvent DMF (Baker Analyzed Reagent) and of all solutes used has been described in the same papers. The solvent mixtures were prepared by weighing and the mole fraction of water in the DMF-water mixtures was corrected for the original water content of the amide as measured by Karl Fischer titration. 

A trend in Karl Fischer coulometric instrumentation is to eliminate the separate cathode compartment in Figure 17-28 to reduce conditioning time required before samples can be analyzed and to eliminate clogging of the membrane.32 The challenge is to minimize interference by products of the cathodic reaction. 

During ageing of the mix, interfacial milk protein hydration also increases simultaneously with protein desorption from the fat globules. The water content of the isolated cream layers after centrifugation of ice cream mix can be analyzed by Karl Fischer titration. From such analyses, interfacial protein hydration can be calculated (Figure 13). 

The water analyses were carried out using an automatic Karl Fischer titrator (Aquatest II) and normally no problems were encountered. However, for the benzene-water-hydrochloric acid system, the acid strongly interfered with the water analyses. With a slight modification of operating procedure, reasonably satisfactory, but low precision, results were obtained For these analyses, the sample was introduced into the analyzer by injection with the syringe needle below the surface of the vessel solution and every benzene injection was preceded by a 100 yl methanol sample. 

Moisture analyzers include a large variety of designs listed here. The list includes their inaccuracies (1) electrolytic hygrometer (2-5% FS), (2) capacitance (3% FS), (3) impedance (3% FS), (4) piezoelectric (10% AR or 2 ppm by volume), (5) heat of adsorption, (6) infrared (0.5-1% FS), (7) microwave (for a 1-15% moisture range, error is within 0.5%, less if corrected for density), (8) Karl Fischer titrator (0.5-1% FS), (9) drying oven (0.5-1% FS), (10) dipole, (11) cavity ring down, (12) fast neutron (0.2% in solid s density corrected), and (13) radio-frequency absorption (5 ppm). 

The condensable part of a sample is separated from carbon dioxide by an expansion through cold traps. The condensate in the cold traps is weighed and analyzed with Karl-Fischer titration (water) and HPLC (carbohydrates). The modifier mass is calculated by weight difference. 

The. sample must be protected from contaciiination by ambient humidity in both [he Karl Fischer and TG inciisiure methods as wdl as in the gravimetrio method. This is necessary for every sample analyzed. Norma]iy the sample is manipulated ill the Kurl fischerdry box maintained at a low humidity (iippioxiiiiaicly 15- 20%... 

When the samples have been withdrawn from the vessels, suitable analytical separations must be available to analyze the reaction. This would include starting materials, products, impurities, and solvents, as appropriate. Quantitations may need to be developed for key components. Karl Fischer titrations may be needed... 

Bauer and Untz analyzed a series of cinchona alkaloids by means of straight-phase HPLC (Fig.5.15). They found that the addition of 2.65 ml of water to 1 liter of the mobile phase (chloroform - isopropanol - diethylamine(940 57 l)), which corresponds to about 75% saturation, gave optimum separation, as regards resolution versus time of analysis. To obtain the correct percentage of water in the mobile phase, the water content present in the mixture was deter-ined by the Karl Fischer method, and water was then added to obtain a final concentration of 2.65 ml/1. 

The Karl Fischer Titration (KFT) is based on a selective reaction of water (Scholz, 1984). Various measures can be taken to bring the water of the sample into contact with the reagents (Isengard, 1995) and the result of these analyzes is indeed the water content of the sample. 

The Karl Fischer test method (ASTM D-1364, ASTM D-6304) covers the direct determination of water in petroleum. In the test, the sample injection in the titration vessel can be performed on a volumetric or gravimetric basis. Viscous samples can be analyzed with a water vaporizer accessory that heats the sample in the evaporation chamber, and the vaporized water is carried into the Karl Fischer titration cell by a dry, inert carrier gas. 

Many manufactured products, as well as solvents and raw materials are analyzed for their water content (percent humidity). Of all the available methods, the Karl Fischer titration is perhaps the most widely used, accounting more than 500 000 determinations performed daily world-wide. 

During tertiary recovery, the produced fluids were analyzed microscopically for the presence of oil-in-water and water-inoil emulsions. Karl Fischer analysis was performed on the produced fluid samples in order to determine the amount of oil present in the aqueous phase and the amount of water present in the oil phase. Also pH readings were recorded for the produced aqueous phase throughout tertiary recovery. 

DSC is a useful means for evaluating both the amount and nature of the water in AM-based polymers. For example, the water volatilization endotherm area (Figure 3) correlates well with volatiles content (oven drying) or total water content (Karl Fischer or DuPont Moisture Analyzer). Extrapolation of the line in Figure 3 suggested a residual water content of 1 percent in the sample which was confirmed by more extensive drying. 

Water analysis of liquids was by Karl Fischer titration. Liquids were analyzed by GC for qualitative or semi-quantitative characterization. Quantitative analysis of selected liquid components was performed by HPLC. The sample was prepared by diluting it with two parts water to cause phase separation of pyrolytic lignin. Simple sugars, anhydrosugars, and other lower molecular weight components such as acetic acid and hydroxyacetaldehyde remain in the aqueous phase. 

ISO 6191 -81. Light olefins for industrial use - Determination of traces of water - Karl Fischer method. ISO 8917-88. Light olefins for industrial use - Determination of water - Guidelines for use of in-line analyzers. 

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