1. Dienstleistungszentrum L?ndlicher Raum Rheinpfalz, Kompetenzzentrum Weinforschung, Breitenweg 71, 67435, Neustadt an der Weinstra?e, Germany 2. Fachbereich Chemie, Fachrichtung Lebensmittelchemie und Toxikologie, Technische Universit?t Kaiserslautern, Erwin-Schr?dinger-Stra?e 52, 67663, Kaiserslautern, Germany
Abstract:
Trace level analyses in complex matrices benefit from heart-cut multidimensional gas chromatographic (MDGC) separations and quantification via a stable isotope dilution assay. Minimization of the potential transfer of co-eluting matrix compounds from the first dimension (1D) separation into the second dimension separation requests narrow cut-windows. Knowledge about the nature of the isotope effect in the separation of labeled and unlabeled compounds allows choosing conditions resulting in at best a co-elution situation in the 1D separation. Since the isotope effect strongly depends on the interactions of the analytes with the stationary phase, an appropriate separation column polarity is mandatory for an isotopic co-elution. With 3-alkyl-2-methoxypyrazines and an ionic liquid stationary phase as an example, optimization of the MDGC method is demonstrated and critical aspects of narrow cut-window definition are discussed.
Figure
Avoiding chromatographic separation of isotopic standards by fine-tuning the isotope effect allows narrow cut-windows in SIDA based MDGC applications.