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16/07/2024 -5368 days left
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Lunch vendor seminar, November 6, 2009 (12:45–14:00)

Modern Multidimensional GCxGC MS Technologies for Analysis Related to Food Quality & Safety

Sponsored by Shimadzu Solution

Qualitative and Quantitative comprehensive GCxGC(q)MS on PCBs and Dioxins in fats using negative chemical ionisation

Dr Hans-Ulrich Baier, Product Specialist GC&GCMS,
Shimadzu Europa GmbH hub@shimadzu.de

Thermal Modulation is the only suitable modulation technology for Comprehensive GCxGC when a MS is used as an detector. That is because Flow modulation techniques dilute the analytes by a relatively high pulse flow (Seeley et al). As quadrupol MS belong to concentration dependend detectors this results in considerably reduction in sensitivity. Here a fast quadrupol detector (small interscan delay) is used to produce at least 10 data points across each modulated fraction in full scan mode. PCBs and Dioxins can be sensitively and selectively analysed by using negative chemical ionization (NCI). By using NH3 as the reagent gas molecular ion respons can be observed also for the smaller congeners (in contrast to dissociative resonance electron capture). Data achieved with EI and NCI mode are compared and the selectivity of the NCI mode for PCBs and Dioxins ares shown with bovine fat matrices as an example. Calibration curves were recorded and quantitative determination was performed.

Flavour profiling with MDGC with MS identification in 1st and 2nd Dimension

Dr Hans-Ulrich Baier, Product Specialist GC&GCMS, Shimadzu Europa GmbH

The characterization of Flavours in food is a widely spread analytical task in the food industry. However the analysis results very often in coelutions of some minor components which are important for the quality of the flavour with other ingredients or with some matrix signals when analyzing food products like cheese. Multidimensional technologies are very suitable to fix those coelution problems. In classical heart cut MDGC in the past however an GC-FID chromatogram was recorded to firstly obtain an area percent report and secondly to find coelution regions in order to cut and transfer those into the second dimensional column which has usually a different polarity (or is a chiral phase) compared to the first dimension. The detector can be an FID or an MS. However in the first dimension there was no identification possible. Here we demonstrate a setup where the signal coming from the first dimension is splitted into the FID and the MS detector in the second dimension. The result is 2 chromatogramms from the first dimension (FID and MS) which allows identification and a better definition of the cut positions in a subsequent run. For those cut runs the FID/MS split line is set to have a reverse flow in order to prevent coelutions from the first and second dimension. Due to the fact that a multi Deans switch is used no shifts in any of the chromatograms are observed (first or second dimension) regardless how many cuts have been programmed. Cuts will be defined by mouse click operations and the corresponding time parameters are automatically set and stored as method parameters. This is a breake through for easy MDGC operation.

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Institue of Chemical Technology International Association of Environmental Analytical Chemistry RIKLT
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