Production and certification of “fresh” reference material for macronutrient analysis

Summary Reference materials for carrying out in-house quality assurance by food laboratories that analyse macronutrients have to date been inadequate. The freeze-dried, very specialized, materials that exist on the market are not always comparable with ordinary food products analysed at those laboratories.A homogeneous, fresh, canned meat material was produced by an ordinary cannery. The total amount of material (pork, nitrite salt and water) was 1700 kg. During production, the fat content was continuously analysed in the different sub-batches and combinations are made accordingly. The material was packed in tin cans containing 200 g, and tested for homogeneity. The shelf life is, by experience, at least five years. A large number of authorized public and industry laboratories participated in the certification procedure. For each constituent different types of standard analytical methods were used. The material is offered for sale together with a certificate, giving mean values for moisture, ash, fat, nitrogen, sodium, sodium chloride and hydroxyproline content. The uncertainty is given as standard deviations including the analytical error and the variations between laboratories, methods and units.     

Calf Intestinal Alkaline Phosphatase I. Improved Isolation Method and Molar Composition of the Purified Phosphatase

A modified and improved method for isolation of calf intestinal alkaline phosphatase is described. By this method 300 to 400 mg of pure enzyme was prepared in a relatively short time. On the basis of the results of ultracentrifugation and of the free, polyacrylamide and immunoelectrophoresis the phosphatase obtained is found to be a homogenous glycoprotein, containing firmly bound zinc, magnesium and phosphoric acid. The molar composition of the enzyme and the catalytic activity were determined with different substrates and buffers.     

The reduction of thoria with graphite

The reduction of thoria with excess graphite was studied with a thermo-balance in vacuum between 1620 and 1920 K. From Th0₂:C=1:50 the rate of reaction was independent of the ratio of the reactants; the endproduct was always ThC₂. The logarithmic weight loss was directly proportional to the time, and theArrhenius plot showed a break at 1710 K: below this temperature the activation energy was found to be 440 kJ, above 260 kJ. The temperature corresponding to the break coincides with the transition temperature of monoclinic to body-centered tetragonal ThC₂.

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Die Reduktion von Thoriumoxid mit Graphit

Zusammenfassung Die Reduktion von Thoriumoxid mit Graphit im Überschuß wurde mittels einer Thermowaage zwischen 1620 und 1920 K im Vakuum untersucht. Ab ThO₂:C=1:50 war die Reaktionsgeschwindigkeit vom Mischungsverhältnis unabhängig; das Endprodukt war immer ThC₂. Der logarithmische Gewichtsverlust war direkt proportional der Zeit, und dieArrheniusgerade zeigte einen Knickpunkt bei 1710 K: unterhalb dieser Temperatur ergab sich eine Aktivierungsenergie von 440 kJ, oberhalb eine solche von 260 kJ. Die Temperatur des Knickpunkts entspricht der Umwandlungstemperatur von monoklinem in tetragonal raumzentriertes ThC₂.

     

Majorisier Ungsrelationen und Fundamentalfolgen eines Ordinalzahlensystems von G. Jäger

Ohne Zusammenfassung