BS EN ISO 4098:2018 pdf download

8.2 Water-soluble matter

Pipette 50,0 ml (6.3) of filtrate into a basin (6.4) which has previously been prepared by heating at700 °C (6.10), cooled in a desiccator (6.11) and accurately weighed (6.i2). Evaporate the filtrate overthe water bath (6.8) and dry the residue at (102 ± 2) °C (6.9) for approximately 2 h.Cool in a desiccator,using only one basin at a time in a small desiccator, and no more than two in a large desiccator. Weighquickly, and repeat the drying, cooling and weighing procedure either until the further reduction inmass does not exceed 2 mg, or the total drying time equals 8 h.Record the final mass and calculate themass of dry residue (m1).

8.3 Water-soluble inorganic matter

Thoroughly wet the residue obtained in 8.2 (see 9.2) in the basin (6.4) with just sufficient 1 mol/lsulfuric acid (5.1), and heat gently over a low flame until no more sulfur trioxide fumes are visible.Heatmore strongly until the basin approaches red heat.Transfer to the muffle furnace (6.10) at 700 C for15 min (see 9.4). Cool in the desiccator and weigh as quickly as possible.Repeat the addition of acid.heating, cooling and weighing until the further reduction in mass does not exceed 2 mg, or the totaldrying time equals 8 h.Record the final mass and calculate the mass of the sulfated residue, (m2).

9 Remarks on the procedure

9.1 lf the specified extraction temperature of (23,5± 3.5)°C cannot be maintained in the test room, it isadvisable to use a vacuum flask of 650 ml to 750 ml capacity.The range of values of the total water-solublematter, WTws,[see Clause 10 a)] is likely to differ by about 0,5 % over the permitted temperature range.