Anwendung der substöchiometrischen Isotopenverdünnungsanalyse zur Bestimmung von Schwefelspuren in organischem Material

Zusammenfassung Zur Bestimmung von Schwefelspuren in organischem Material wurde eine Kombination von Wickbold-Aufschluß und Isotopenverdünnungsanalyse vorgeschlagen und anhand von Modellanalysen untersucht. Im unteren ppm-Bereich ergaben sich rel. Standardabweichungen von weniger als 10%. Das Verfahren wurde durch Vergleichsmessungen an Proben aus der industriellen Praxis sowie durch systematische Störungsuntersuchungen überprüft. Vergleichsmethode ist die nach einem oxydativen Aufschluß häufig angewendete Reduktion des Sulfats zu Sulfid mit anschließender merkurimetrischer Titration. Die mit beiden Verfahren erhaltenen Ergebnisse wurden diskutiert.

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Application of the substoichiometric isotope dilution analysis to the determination of traces of sulphur in organic material

Summary The combination of a Wickbold combustion with an isotope dilution analysis is proposed for the determination of traces of sulfur in organic material. An evaluation of the method using synthetic mixtures yields a relative standard deviation of less than 10% at the lower ppm-level. A further examination of the described technique is made by comparative analytical studies using industrial samples as well as by a systematic investigation of interferences. The reduction of sulfate followed by the mercurimetric titration of the sulfide formed is used as a reference method. The results obtained with both procedures are discussed.

     

MC SCF optimization using the direct,restricted step,second-order norm-extended optimization method

The potential of a direct, restricted step, second order MC SCF computer program is illustrated with a large configuration space calculation containing 24156 configuration state functions on the ³B₁ state of methylene.     

Solutions of the anti-self-dualSU(2) Yang-Mills equations gained from the inverse scattering method

By applying the inverse scattering method in connection with a dressing procedure a huge class of solutions of the anti-self-dualSU(2) Yang-Mills equation is obtained. This class contains also the well-known't Hooft instantions.     

Criteria for sign regularity of sets of matrices

We consider matrix intervals with respect to a certain “checkerboard” partial ordering. We show that every real matrix contained in a matrix interval is sign-regular if two special matrices taken from that matrix interval are sign-regular.