The standard applies to all types of wastewater and surface water. The method can be used in the presence of a maximum of 1 mg of chromate ions, 5 mg of copper ions, 10 mg of each of the metal ions: lead, aluminium, nickel, iron(II) and chromium, in the sample for analysis Interfering organic substances are removed by heating with an alkaline potassium permanganate solution (see 6.1). Sulphite ions must be removed if more than 1 mg is present in the analytical sample (see 6.2). Sulfide ions must be removed (see 6.2). Iron(III) ions must be reduced when more than 1 mg is present in the sample for analysis (see 6.3).
NEN 6660-1981 history
1981NEN 6660-1981 Waste water - Titrimetric determination of chloride content (mercurimetric)