Über die dilatometrisch indizierten Titrationen

With the help of a dilatometer which permits the continuous determination of volume changes occuring in chemical reactions in aqueous solutions, the volume change during the precipitation of BaSO₄ was followed and applied to the determination of the endpoint of the precipitation. In the case of precipitations of 1 mM BaSO₄ the end-point determination can be reproduced with a standard deviation of less than 0.2%. A strict linearity between the amount of Na₂SO₄ applied and the position of the end-point does not exist. However, a correction factor could be established, so that the absolute determination of sulphate is possible (standard deviation 0.2%). The time required to carry out a single measurement is about 1.5 min. The acid concentration does not influence the composition. On the other hand, the composition was shown to be considerably dependent on Na⁺ and NH₄ ⁺ ions. The presence of the cation N(CH₃)₄ ⁺ does not alter the composition of the precipitate. It is obviously too big to substitute the Ba²⁺ ion.     

Klinische Bedeutung und Technik der Blutbleibestimmung mit Zeeman-AAS

Zusammenfassung Nach einem kurzen Überblick über die klinischen Aspekte von Bleivergiftungen wird eine einfache direkte Methode zur Blutbleibestimmung beschrieben. Sie beruht auf Zeeman-AAS mit Feststoff-Graphitrohr-Küvette und Matrixisoformierung mit 1%iger Phosphorsäure und ist gut geeignet für die klinische Routineanalyse.

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Clinical significance and technique of blood-lead determination with Zeeman AAS

Summary After a short review concerning the clinical aspects of lead intoxication, a simple direct determination is described for lead in blood and urine. It is based on Zeeman AAS with solid graphite tube cuvette and matrix isoformation with 1% phosphoric acid, and is useful in clinical routine analysis.

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Vorgetragen anläßlich des Kolloquiums Stand und Perspektive der Feststoffanalyse mit AAS, Wetzlar, 8.–10. 10. 1984     

Leitf?higkeitstitrationen

Ohne Zusammenfassung     

S-benzylthiouronium salts of some carboxylic acids,sulfonic acids,and phenols

116 S-Benzylthiouronium suits have been prepared and were, if possible, checked by titration with perchloric acid in glacial acetic acid on a semi-micro scale. Out of these, 110 are salts of carboxylic acids, 2 of snlfonic acids, and 4 of nitrophenols. The melting points determined according to a standard procedure are given.     

Exploring Effects of Protease Choice and Protease Combinations in Enzymatic Protein Hydrolysis of Poultry By-Products

A study of the effects of single and combined protease hydrolysis on myofibrillar versus collagenous proteins of poultry by-products has been conducted. The aim was to contribute with knowledge for increased value creation of all constituents of these complex by-products. A rational approach was implemented for selecting proteases exhibiting the most different activity towards the major protein-rich constituents of mechanically deboned chicken residue (MDCR). An initial activity screening of 18 proteases on chicken meat, turkey tendons and MDCR was conducted. Based on weight yield, size exclusion chromatography (SEC) and SDS-PAGE, stem Bromelain and Endocut-02 were selected. Studies on hydrolysis of four different poultry by-products at 40 °C, evaluated by protein yield, SEC, and SDS-PAGE, indicate that the proteases’ selectivity difference can be utilized in tailor-making hydrolysates, enriched in either meat- and collagen-derived peptides or gelatin. Three modes of stem Bromelain and Endocut-02 combinations during hydrolysis of MDCR were performed and compared with single protease hydrolysis. All modes of the protease combinations resulted in a similar approximately 15% increase in product yield, with products exhibiting similar SEC and SDS-PAGE profiles. This shows that irrespective of the modes of combination, the use of more than one enzyme in hydrolysis of collagen-rich material can provide means to increase the total protein yield and ultimately contribute to increased value creation of poultry by-products.     

HPLC/MS-Transfer mit Hilfe eines beheizten Stickstoffstroms

Ohne Zusammenfassung

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HPLC/MS-transfer using a flow of heated nitrogen