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Vitamin B6 comprises an important set of molecules tightly interwoven with the human amino acid, fatty acid, and carbohydrate metabolism. Analytical methods striving for the quantification of individual B6 vitamers so far mostly rely on methods based on HPLC in combination with fluorescence detection, but their application encounters multiple difficulties due to the chemical divergence of the single vitamers. The present study describes the development of a method based on LC-MS/MS and stable isotope dilution assay (SIDA) for the simultaneous quantification of five vitamers (PN, PL, PM, PMP, and PNG) of the B6 group in food samples. [13C3]-PN, [13C3]-PL, and [13C6]-PNG were applied as internal standards for the analysis of PN, PL, and PNG. PM and PMP were quantified via matrix-matched calibration referring to [13C3]-PN. The developed method was validated using starch matrix. The limits of detection and quantification ranged from 0.0028 to 0.02 mg/kg and from 0.0085 to 0.059 mg/kg, respectively, for all analytes. Calculated recoveries varied from 92 to 111%. Intra-injection precisions ranged from 0 to 9%, inter-day precisions from 4 to 10%, and intra-day precisions from 4 to 10%. A total of 14 plant-based food samples including fruits, vegetables, and cereals were examined for their content of vitamin B6 using the validated method. Furthermore, the first quantitation of PNG without enzymatic steps or divergent internal standards was undertaken utilizing LC-MS/MS and SIDA.

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Handlungstheorien stehen im Zentrum der gegenwärtigen soziologischen Theoriediskussion. Zugleich blicken diese Ansätze auf eine lange Tradition zurück und zählen zum unbestrittenen Kanon des Fachs. Dennoch geben die verschiedenen Theorien keine eindeutige Antwort auf die Frage, was soziales Handeln ist und inwiefern es gesellschaftlich bestimmt wird. Dieses Lehrbuch bringt mit einer systematischen und konzisen Darstellung der wichtigsten Handlungstheorien von David Hume und Max Weber über George H. Mead und Talcott Parsons bis James S. Coleman und Jürgen Habermas Klarheit in dieses unübersichtliche Theoriefeld. Das didaktische Konzept des Bandes, anhand von Leitfragen die einzelnen Positionen miteinander in Beziehung zu bringen, ist konsequent auf die Bedürfnisse eines strukturierten BA-Studiums zugeschnitten.