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Development and validation of an HPLC method with fluorescence detection for the determination of fluorescent whitening agents migrating from plastic beverage cups

An HPLC method with fluorescence detection has been developed and validated for the quantification of 6 fluorescent whitening agents (FWAs) in food contact plastic cups after extraction and in official food simulants after migration at 70 oC for 2 h. The sensitivity of the method was high, with LODs ranging from 0.053 to 0.251 μg L-1 and LOQs from 0.107 to 0.504 μg L-1. Accuracy and precision were highly acceptable, with recoveries being higher than 82% and RSDs (%) below 16%. The expanded combined uncertainty was found to be less than 23% for the measurements of all the studied FWAs. For the extraction of the analytes from food contact materials (FCM), accelerated solvent extraction (ASE) and Soxhlet extraction have been applied using ethanol as the extraction solvent. The results obtained for FWA in 10 different food plastic cups, made from different polymers, were compared. The ASE technique proved to be faster, more effective and more efficient than Soxhlet extraction. Migration tests with official food simulants from EU Regulation 10/2011 showed that the studied substances could potentially migrate using the selected migration conditions. The most pronounced effect was observed in case of simulant D1 (50% w/v ethanol in water). The analytical method proved to be a simple, fast, sensitive and reliable tool for the simultaneous quantification of six of the most used FWAs in both FCM extracts and food simulants after migration experiments.