Abstract
Different silicone baking moulds (37 samples) were characterized with respect to potential migrating substances using 1H-NMR, RP-HPLC–UV/ELSD and GC techniques. In all cases cyclic organosiloxane oligomers with the formula [Si(CH3)2–O] n were identified (n = 6 … 50). Additionally, linear, partly hydroxyl-terminated organosiloxanes HO–[Si(CH3)2–O] n –H (n = 7 … 20) were found in 13 samples. No substances other than siloxanes could be detected, meaning the migrants mainly consist of organopolysiloxanes. Based on this knowledge, a 1H-NMR quantification method for siloxanes was established for the analysis of both simulants and foodstuffs. Validation of the 1H-NMR method gave suitable performance characteristics: limit of detection 8.7 mg kg–1 oil, coefficient of variation 7.8% (at a level of 1.0 mg kg–1 food). Migration studies were carried out with simulants (olive oil, isooctane, ethanol (95%), Tenax) as well as preparation of different cakes. From the 1st to 10th experiment, siloxane migration into cakes only slightly decreased, with a significant dependence on fat content. Migration never exceeded a level of 21 mg kg–1 (3 mg dm–2) and was, therefore, well below the overall migration limit of 60 mg kg–1 (10 mg dm–2). However, migration behaviour into simulants differed completely from these results.
Acknowledgements
The authors thank Wacker Co. (Burghausen, Germany) for financial support of these studies. We also acknowledge Dr Margit Gruner and Annett Rudolph (Technical University of Dresden, Institute of Organic Chemistry) for numerous NMR measurements and Dr Uwe Schwarzenbolz (Technical University of Dresden, Chair of Food Chemistry) for LC–MS measurements.