Paragraph 6 PREPARATION OF THE ALIQUOT PORTION TO BE ANALYSED

Using a pipette, take an aliquot portion of the extraction solution obtained by method 15 or 17, containing between 15 and 50 mg of Ca ( = 21 to 70 mg of CaO). Let the volume of this aliquot be v₂. Pour into a 400 ml beaker. If necessary, neutralise (change of indicator (4.7) from green to blue) with a few drops of the ammonia solution (4.3).

Add 1 ml of the citric acid solution (4.5) and 5 ml of ammonium chloride solution (4.6).