Homogenization

The pooled beef samples are prepared using a cutter on dry ice in order to shred any tendons present. A pool sample is created from five individual samples (approx. 140 g). The homogenized pool samples are then filled into recyclable plastic cups. A retain sample of 300 g is stored in frozen form (-20 °C) after homogenization. All poultry samples were sent to the BfR already homogenized and could be sent directly to the contract laboratory for analysis.

Sample preparation and determination of the vitamins

Sample preparation is carried out in accordance with DIN EN 12823 for vitamin A and DIN EN 12821 for vitamin D3 and 25-(OH)-vitamin D3. Vitamin A, vitamin D3 and 25-(OH)-vitamin D3 are extracted after alkaline saponification by shaking with n-hexane/tBME. Vitamin A is then determined via HPLC (normal phase) using fluorescence detection. Fluorescence detection makes the measurement method for vitamin A very specific. Finally, all-trans-retinol is identified on the basis of the retention time and quantified using an external standard. The content of vitamin D3 and 25-(OH)-vitamin D3 is quantified after enrichment of the sample extract by RP-HPLC-MS/MS detection using an isotope-labeled standard. The addition of isotope-labeled vitamin D and 25-(OH)-vitamin D3 ensures the compensation of matrix effects. The evaluation is carried out every working day using an external 5-point calibration for vitamin A, vitamin D3 and 25-(OH)-vitamin D3, whereby the purity and content of all standard stock solutions are determined photometrically every working day.

Initial preliminary results