Division 5.2.1 Feed

Weigh to the nearest 0,01 g, from 5 g to 10 g of the sample into a 250 ml conical flask with stopper. Add 100,0 ml of acidified methanol (3.8) by pipette. Stopper loosely and swirl to disperse. Place the flask in an ultrasonic bath (4.1) at approximately 40 ^oC for 20 minutes, then remove and cool to room temperature. Allow to stand for about 1 hour until the suspended matter has settled, then filter an aliquot portion through a 0,45 μm membrane filter (4.2) into a suitable vessel. Proceed to the HPLC determination (5.3).