BS 15835:2010 pdf download – Foodstuffs — Determination of ochratoxin A in cereal based foods for infants and young children — HPLC method with immunoaffinity column cleanup and fluorescence detection

BS 15835:2010 pdf download – Foodstuffs — Determination of ochratoxin A in cereal based foods for infants and young children — HPLC method with immunoaffinity column cleanup and fluorescence detection 6 Procedure 6.1 Extraction Stir the sample thoroughly before removing an analytical test portion. Weigh, to the nearest 0,1 g, a 25 g test portion of baby food sample into a centrifuge bottle (5.9). Add 100 ml of the mixture of phosphoric acid solution and sodium chloride solution (4.15). Mix for 1 min on a Vortex mixer (5.20). Add 50 ml of tert-butyl methyl ether (4.22). Blend for 2 min with a high speed blender (5.2). Centrifuge for 10 min at 15 300 g with cooling at approximately 4 °C. Transfer the upper organic layer to a capped conical flask or measuring cylinder. Re-extract with a second 50 ml portion of tert-butyl methyl ether, blending again for 2 min. After centrifugation under the same conditions, combine the two organic phases. Pour an aliquot of 75 ml of the combined organic phases into a round bottomed flask (5.15) and evaporate at 35 °C to 40 °C in a rotary evaporator (5.10) until no more solvent distils. Re-dissolve the remaining fatty residue as follows to obtain an extract in a mixture of 15 parts per volume of methanol (4.19) and 85 parts per volume of PBS solution (4.14). Add 3 ml of methanol and thoroughly rinse the walls of the flask. Transfer the methanol extract into a separating funnel (5.19) by using a Pasteur pipette. Repeat this step once again with a new portion of 3 ml of methanol. Combine both methanol extracts in the separating funnel. Dilute by addition of 34 ml of PBS solution (4.14) to the separating funnel and shake vigorously for 1 min. Add 50 ml of hexane (4.18) to the separating funnel and shake gently for 1 min. Allow the layers to separate, then pour off the lower layer into a second separating funnel and discard the top hexane layer. Repeat this operation with a second portion of 50 ml of hexane. Pour off the lower layer into a centrifuge bottle (5.9) and centrifuge for 10 min at 15 300 g and approximately 4 °C in order to separate any fatty residue. Drain into a measuring cylinder through a funnel and filter paper (5.6). NOTE Try to avoid the re-mixing of aqueous and organic phases. If draining...