Division 6 PROCEDURE

1. 6.1.

   Add to each of three separate ion exchange chromatography columns (point 5.1) 50 ml of the ion exchange resin to be tested, washed and treated in accordance with the manufacturer's directions for preparing resins for use with food.

2. 6.2.

   For the anionic resins, pass the three extracting solvents (points 4.1, 4.2 and 4.3) separately through the prepared columns (point 6.1) at a flow rate of 350 to 450 ml/h. Discard the first litre of eluate in each case and collect the next two litres in measuring cylinders (point 5.2). For the cationic resins, pass only solvents referred to in points 4.1 and 4.2 through the columns prepared for this purpose.

3. 6.3.

   Evaporate the three eluates over a hotplate or with an infrared evaporator (point 5.7) in separate evaporating dishes (point 5.3) which have been previously cleaned and weighed (m0). Place the dishes in an oven (point 5.4) and dry to constant weight (m1).

4. 6.4.

   After recording the constant weight (point 6.3), place the evaporating dish in the muffle furnace (point 5.5) and ash to constant weight (m2).

5. 6.5.

   Calculate the organic matter extracted (point 7.1). If the result is greater than 1 mg/l, carry out a blank test on the reagents and recalculate the weight of organic matter extracted.

The blank test shall be carried out by repeating the operations referred to in points 6.3 and 6.4 but using two litres of the extracting solvent, to give weights m3 and m4 in points 6.3 and 6.4 respectively.