Division 4.2.1 Digestion in the wet stage

Weigh out 1 to 2 g of the homogenized sample, according to presumed quantity of calcium, into a Kjeldahl flask.

In the case of liquid products, weigh out 10 g and concentrate down to a reduced volume (2 to 3 ml).

Add 10 ml concentrated nitric acid (2.1) and 2,5 ml sulphuric acid (2.4).

Start heating very gently until white fumes appear.

At that point the solution should be clear and colourless.

If this is not so, carefully add a few drops of nitric acid (2.1) and continue heating until white fumes appear.

Once destruction is complete, decant the solution which should be reduced to 2 to 3 ml into a 25 ml volumetric flask and make up to volume with double-distilled water.

Samples prepared in this fashion are analyzed and compared with standard 10 % sulphuric acid solutions (2.4).