The German bakery waste incident

Abstract

Samples were homogenized and tested by a validated method routinely used for dioxins monitoring in food and animal feed and successfully verified in a number of inter -laboratory studies. Samples were extracted by accelerated solvent extraction (ASE) using an ASE 300 Dionex instrument with a mixture of n -hexane and acetone 80:20 (v/v). The clean-up procedure was based on an acid/base partitioning and a further purification was then performed according to EPA Method 1613 Rev. B by means of an automated clean-up process with Power-Prep system (Fluid Management System) using disposable columns (multilayer silica, alumina and carbon). PCDD/Fs were separated by high resolution gas chromatography (HRGC) on a DB -5 MS capillary column (60 m x 0.25 mm, 0.1 µm) and determined by high resolution mass spectrometry (HRMS), at a resolution of 10000 in the selected ion monitoring (SIM) mode. The HRGC/HRMS system consisted of a GC Trace Series 2000 (ThermoQuest) coupled with a MAT 95 XL (ThermoFinnigan). The quantification of the seventeen 2,3,7,8 chlorine -substituted dioxins/furans was accomplished by the isotope dilution method. TEQ values were calculated using WHO -TEFs. According to the European legislation, WHO-TEQs were calculated as upper bound concentrations assuming that all values of specific dioxins congeners below the limit of determination (LOD) are equal to the respective LOD. Results and discussion The dioxin levels found in the first egg sample was equal to 88.11 pg WHO -TEQ/g fat, with a major abundance of PCDDs in respect to PCDFs. The further samples taken in the same farm gave the following results: - eggs 33.00 pg WHO-TEQ/g fat, laying hens meat 45.16 pg WHO -TEQ/g fat, thus confirming the contamination found in the previously analysed egg sample; - cheese (from free grazing cattle) 0.54 pg WHO -TEQ/g fat, excluding pollution of environmental origin; - chicken ration 0.050 pg WHO-TEQ/g, excluding contamination due to feed products; - wood-shaving litter 50.82 pg WHO -TEQ/g, wood shavings 40.10 pg WHO -TEQ/g, with similar congener profiles, thus obtaining a clear identification of the contaminated material from which dioxins were transferred to poultry. The PCDD/Fs profiles found in eggs, meat, litter and wood shavings are showed in Figure 1. All samples were characterized by a predominance of PCDDs over PCDFs. In eggs, wood shavings and litter the PCDFs levels amounted to 8% of PCDDs concentration. In meat PCDFs contribution raised to 16%. The congeners profile was the same in all contaminated matrices. OCDD was the most abundant congener among dioxins (range 54% - 82%), followed by 1,2,3,4,6,7,8 -HpCDD (range 11% – 24%). OCDF was predominant among