2-Isopropylthioxanthone (2-ITX) in food and food packaging materials on the German market.

To elucidate the occurrence of the photo-initiator, 2-isopropylthioxanthone (2-ITX), more than 100 food products on the German market, packed in cartons, plastic cups and foils, were investigated. For this, a rapid method to detect 2-ITX in food packaging materials was established. In case of positive findings, the accompanying foodstuffs were analysed in a subsequent step using different extraction methods, depending on the fat content of the food. Determination of the photo-initiator was done by high-performance liquid chromatography with diode array and fluorescence detection (HPLC-DAD/FLD). Recoveries ranged between 94 and 106% for non-fatty (RSD <or= 1.1) and between 80 and 105% for fatty foods (RSD <or= 8.5). The limit of detection and limit of quantification were determined to 2 and 5 microg l(-1). 2-ITX was detected in 36 of 137 packages (26%) and significant migration occurred in 75% of the packaging materials tested positive. The levels of 2-ITX ranged up to 357 microg kg(-1) in orange juice.