Utilização de índices r e R obtidos de programas interlaboratoriais para o controle de precisão de método analítico: Determinação de água por Karl Fischer

Values of repeatability (r) and reproducibility (R) are parameters of an analytical method. They are related to the maximum difference between two results of analysis (permissible range) and can be obtained by interlaboratorial comparisons. They represent great importance for the quality control of the results and decisions about the fitness-for-purpose of the method. Water determination in fuel oil samples were performed by 16 laboratories, using the Karl Fischer reaction, during the period from June 1997 to December 1999. Values of r and R were presented. Discussion is made in terms of the main factors that would be contribution to analytical method variabilities and uncertainties of final results.

Metodi convenzionali ed innovativi per la misura del contenuto d'acqua negli oli extravergini d’oliva

Nell’ambito del presente lavoro sperimentale sono state prese in considerazione differenti tecniche, tradizionali ed innovative, per la determinazione del contenuto di acqua presente negli oli extravergine di oliva. Seppur presente nell'olio in quantità limitata, l'acqua é in grado di favorire la dissoluzione e veicolare componenti minori idrofilici (come le molecole a struttura fenolica e polifenolica) all'interno di micelle inverse che si creano nella matrice lipidica quando alla superficie acqua-olio si aggregano composti anfifilici (come i digliceridi, i monogliceridi, gli acidi grassi liberi, i fosfolipidi etc.) che danno luogo alla formazione di aggregati colloidali. I risultati ottenuti su un set di 60 campioni hanno evidenziato come esistano correlazioni positive e soddisfacenti tra le diverse metodiche analitiche tradizionali quali la titolazione titrimetrica di Karl Fisher e quelle gravimetriche per essiccamento in stufa o mediante termobilancia. La migliore correlazione in termini di R2 con valore pari a circa 0,82 è stata ottenuta tra i metodi Karl Fisher ed essiccamento in stufa, mentre per esempio quella tra i due metodi gravimetrici (stufa e termobilancia) ha fatto registrare un valore inferiore (0,70). Pur essendosi verificate delle soddisfacenti correlazioni tra le tre tecniche tradizionali, i valori del contenuto in acqua dei campioni si sono presentati variabili in funzione dell'utilizzo di una modalità di misurazione rispetto all'altra. Tale variabilità é funzione di diversi fattori: la difficoltà di determinare l'acqua fortemente legata nel caso dei metodi per essiccamento; la perdita in peso causata anche da altri componenti in grado di volatilizzare alle condizioni analitiche adottate; la possibilità di formazione di composti non originariamente presenti come risultato di modificazioni chimiche indotte dall'elevata temperatura. Il contenuto di acqua è stato quindi stimato anche mediante una tecnica innovativa a basso costo basata su misure dielettriche. Considerato che l’olio extravergine di oliva è noto essere un ottimo isolante, il fenomeno dielettrico osservato risulta essere di natura capacitiva. Il risultato di correlazione ottenuto su un set di 23 oli extravergini di oliva applicando in parallelo questa tecnica rapida e la misura gravimetrica con stufa (che é un metodo ISO), è da considerarsi soddisfacente, con un R2 pari anche in questo caso a 0,82. In conclusione, le tecniche attualmente utilizzate per la determinazione del contenuto di acqua in oli extravergine di oliva risultano tra loro correlate. Considerando che tali tecniche tradizionali sono dispendiose o in termini di tempo (gravimetrico mediante stufa) o in termini di consumo di reagenti e solventi (titrimetrico con reattivo di Karl Fischer), il nuovo approccio sperimentato mediante misure capacitive può essere considerato molto interessante anche se, sicuramente, sarà da applicare ad un numero più ampio di campioni per rendere l'evidenza sperimentale più robusta.

Antisemiten und Gymnasiallehrer : ein Protest

von Karl Fischer

Heinrich v. Treitschke und sein Wort über unser Judenthum : ein Wort zur Verständigung

von Karl Fischer

Gutmeinung über den Talmud der Hebräer : (nach e. Manuscript vom Jahre 1802)

verfaßt von Karl Fischer

Geochemistry of low-temperatuer altered basalts of ODP Hole 136-843B

The mineralogy and chemistry of altered basalts and the stable isotopic compositions of secondary vein carbonates were studied in cores from Ocean Drilling Program Hole 843B, located in 95-Ma crust of the Hawaiian Arch. Millimeter- to centimeter-sized dark alteration halos around veins are 5%-15% altered to celadonite and Fe-oxyhydroxides, plus minor saponite and calcite. Adjacent gray host rocks are about 15% altered to saponite and calcite. The dark halos are enriched in H2O+, CO2, FeT, K2O, MnO, and Fe3+/FeT and depleted in SiO2, Al2O3, MgO, and TiO2 relative to gray host rocks. Brown alteration halos occur around veins where veins are more abundant, and are similar to dark halos, but contain more Fe-oxyhydroxides and exhibit greater Fe2O3T contents and higher Fe3+/FeT. Stable isotopic compositions of vein carbonates are consistent with their precipitation from seawater at temperatures of 5°-40°C. Crosscutting relationships of veins and zoned vein and vesicle fillings reveal a sequence of secondary mineral formation and alteration conditions. Celadonite and Fe-oxyhydroxides formed and dark alteration halos developed relatively early, under oxidizing conditions at low temperatures (<50°C). Saponite formed later at lower seawater/rock ratios and under more reducing conditions. Calcite and pyrite formed last in veins and vesicles from more evolved, seawaterderived fluids at temperatures of 5°-40°C. A second stage of celadonite, with compositions distinct from the early celadonite, also occurred relatively late (within the "calcite stage"), and may be related to refracturing of the crust and introduction of less-evolved seawater solutions into the rocks. Trends to higher K2O contents are attributed to alteration, but high K/Ti, Ba, and Zr contents indicate the presence of enriched or transitional MORB. CO2 contents of Pacific ODP cores exhibit a general increase with age suggesting progressive fixation of CO2 as calcite in the crust, but this could be complicated by local heterogeneities in fracturing and calcite formation in the crust.

Novel method for the determination of water content and higher heating value of pyrolysis oil

This research provides a novel approach for the determination of water content and higher heating value of pyrolysis oil. Pyrolysis oil from Napier grass was used in this study. Water content was determined with pH adjustment using a Karl Fischer titration unit. An equation for actual water in the oil was developed and used, and the results were compared with the traditional Karl Fischer method. The oil was found to have between 42 and 64% moisture under the same pyrolysis condition depending on the properties of the Napier grass prior to the pyrolysis. The higher heating value of the pyrolysis oil was determined using an oil-diesel mixture, and 20 to 25 wt% of the oil in the mixture gave optimum and stable results. A new model was developed for evaluation of higher heating value of dry pyrolysis oil. The dry oil has higher heating values in the range between 19 and 26 MJ/kg. The developed protocols and equations may serve as a reliable alternative means for establishing the actual water content and the higher heating value of pyrolysis oil.

Thermal stability of sewage sludge pyrolysis oil

The stability of the oil phase obtained from intermediate pyrolysis process was used for this investigation. The analysis was based on standard methods of determining kinematic viscosity, gas - chromatography / mass - spectrometry for compositional changes, FT-IR for functional group, Karl Fischer titration for water content and bomb calorimeter for higher heaating values. The methods were used to determine changes that occurred during ageing. The temperatures used for thermal testing were 60 °C and 80 °C for the periods of 72 and 168 h. Methanol and biodiesel were used as solvents for the analysis. The bio-oil samples contained 10 % methanol, 10 % Biodiesel, 20 % Biodiesel and unstabilised pyrolysis oil. The tests carried out at 80 °C showed drastic changes compared to those at 60 °C. The bio-oil samples containing 20 % biodiesel proved to be more stable than those with 10 % methanol. The unstabilised pyrolysis oil showed the greatest changes in viscosity, composition change and highest increase in water content. The measurement of kinematic viscosity and gas chromatograph mass spectrometry were found to be more reliable for predicting the ageing process.

Na 1 Nachlass Max Horkheimer, 14 - Korrespondenzen u.a. mit Hugo Fischer und Karl August Wittfogel (p. I 7, 224-429)

1 Brief von Max Horkheimer an Rosel Favez, 03.12.1935; 5 Briefe zwischen Sidney B. Fay von der Bureau of International Search Cambridge, Massachusetts und Max Horkheimer, 1939-1941; 1 Brief von Max Horkheimer an James Feibleman, 02.03.1942; 5 Briefe von Hans Feibelmann an Max Horkheimer, 1936-1937; 2 Briefe zwischen Babette Feigenbaum und Max Horkheimer, 29.04.1941, 05.05.1941; 1 Brief von Arthur Feiler an Max Horkheimer, 15.10.1939; 1 Brief von Max Horkheimer an Adolf Feitler, 03.01.1935; 3 Briefe zwischen Frederick V. Filed von dem American Council Institute of Pacific Relations und Max Horkheimer, 1937, 05.04.1937; 9 Briefe zwischen Thea Field, Lowell Field und Max Horkheimer, 1935-1941; 1 Brief von Max Horkheimer an Finkelstein, 18.09.1941; 7 Briefe zwischen Harry Finkelstein und Max Horkheimer, 1936-1940; 1 Brief von Louis Finkelstein an Robert MacIver, 29.05.1940; 2 Briefe zwischen Louis Finkelstein und Max Horkheimer, 06.06.1940, 04.06.1940; 15 Briefe zwischen Hugo Fischer und Max Horkheimer, 1937-1938; 1 Brief von Hugo Fischer an P. Tillich; 1 Brief von Hugo Fischer an Karl A. Wittfogel, 17.06.1940; 2 Briefe von Max Horkheimer an Ernest Manheim, April 1942; 1 Brief von Alexander Farquharson an Max Horkheimer, 20.01.1940; 3 Briefe zwischen dem Institute of International Education, New York Edgar J. Fisher und Max Horkheimer, Oktober 1938, 18.10.1938; 10 Briefe zwischen Paul Fischer und Max Horkheimer, 1938-1940; 2 Briefe zwischen der Hessian Hills School New York und Max Horkheimer, 21.02.1938, 28.02.1938; 2 Briefe zwischen Dorothy Canfield Fisher und Max Horkheimer, 24.01.1939, 19.01.1939; 1 Brief von Ossip K. Flechtheim an Max Horkheimer, 04.01.1941; 2 Briefe zwischen der University of Minnesota, Minneapolis und Max Horkheimer, 02.08.1945, 15.09.1945; 3 Briefe zwischen Leo Löwenthal und Max Horkheimer, 1943-1945, 17.08.1945; 2 Briefe zwischen der University of Denver, Colorado und Max Horkheimer, 11.05.1943, 28.05.1943; 1 Brief von dem Institute Universitaire De Hautes Etudes Internationales Genf an Max Horkheimer, 25.01.1939; 1 Brief von Hans Kelsen an Max Horkheimer, 30.01.1939; Lebenslauf und 2 Empfehlungsschreiben von Max Fleischmann für Prof. Edwin Borchard; 1 Brief von der Columbia University in the City of New York an Franz Neumann, 17.04.1940; 3 Briefe zwischen Philipp Flesch und Max Horkheimer, 26.03.1940, 1939-1940; 17 Briefe zwischen Babette Fletcher, Theo Fletcher und Max Horkheimer, 1941-1950; 1 Brief von Max Horkheimer an Abraham Flexner, 07.06.1939; 1 Brief von Robert Fließ an Max Horkheimer, 24.10.1938; 1 Brief von der Foreign Policy Association New York an Max Horkheimer, 03.11.1934; 1 Brief von Max Horkheimer an Rudolf Forster, 10.01.1940; 2 Briefe von der Fortune Time & Life Building New York und Max Horkheimer, 1938-1940; 4 Briefe zwischen Siegmund H. Foulkes (Fuchs) und Max Horkheimer, 1936-1937, 31.12.1936; 5 Briefe zwischen Elsie M. Foulstone und Max Horkheimer, 1941; 1 Brief von Mary Fox an Max Horkheimer, 09.12.1938; 5 Briefe zwischen Ernst Fraenkel und Max Horkheimer, 1936-1938; 1 Heiratsanzeige Liesl Frank; 7 Briefe zwischen Philipp Frank und Max Horkheimer, 1937-1939; 6 Briefe zwischen Lothar G. Frank und Max Horkheimer, 1941; 7 Briefe zwischen Felix Frankfurter und Max Horkheimer, 1937-1941; 2 Briefe zwischen Joseph Freeman und Max Horkheimer, 22.11.1944; 1 Brief von der Free Synagogue New York an Max Horkheimer, 14.11.1938; 2 Briefe zwsichen Benjamin Freilichmann und Max Horkheimer, 07.01.1939, 23.01.1939; 2 Briefe zwischen dem Frenkel Travel Service New York und Max Horkheimer, 21.02.1936, 23.02.1936; 2 Briefe zwischen Hugo Freund und Max Horkheimer, 14.11.1938, 18.11.1938; 2 Briefe zwischen Julius A. Jr. Freynick und Max Horkheimer, 11.09.1939, 18.09.1939;

Else Gentner-Fischer, Karl Gentner, Doppelbildnis, Kniestück

Signatur des Originals: S 36/F04097

Else Gentner-Fischer, Karl Gentner, Doppelbildnis, Kniestück

Signatur des Originals: S 36/F04098

Else Gentner-Fischer, Karl Gentner, {[N.N.], Gruppenbildnis

Signatur des Originals: S 36/F04099

Else Gentner-Fischer, Karl Gentner, Doppelbildnis, Kniestück

Signatur des Originals: S 36/F04100