The standard applies to rainwater that contains at least 3 ^mol/l of chloride (= 0.1 mg/l), 1 nmol/l of phosphate (= 0.1 mg/l), 2 rtmol/l of nitrate ( = 0.1 mg/l) and 1 ^mol/l of sulphate (= 0.1 mg/l). The method is suitable for small quantities of analysis sample (approx. 3 ml). Notes 1. Fluoride can also be determined ion chromatographically, but determination according to this standard is impaired by the presence of formic acid, acetic acid and carbonate when detected with a conductivity meter. In addition, the resolution of the fluoride peak (which is found in the ion chromatogram before the chloride peak) and the injection peak ("water dip", see Figure 3) is usually too low. Fluoride can therefore be better detected potentiometrically, see NEN 6589. 2. If desired, nitrite can also be determined according to this standard. However, the nitrite concentration in rainwater is generally very low. In contrast, high concentrations are sometimes found in fog and dew. In the ion chromatogram (see figure 3), the nitrite peak is located between the chloride and the phosphate peak.
NEN 6588-1988 history
1988NEN 6588-1988 Rain water - Determination of chloride, phosphate, nitrate and sulphate content by ionchromatography