Chloride ions in SE of soils, when free of particulates (i.e. no particles >0.45 μm) can be measured by ICPAES if the instrument can operate at a wavelength of 134.724 nm. Spectroflame™ ICP is one that can meet this criterion. Almost always, the SE must be diluted at least to concentrations no greater than those in typical 1:5 soil/water extracts. Dilutions are essential (at least 1:10) when aqueous solution concentrations exceed around 200 mg Cl–/L.
Reagent Water
As for Method 14E2a.
Chloride Primary Standard
1 mL contains 2 mg of Cl.
As for Method 5A2a
Chloride Working Standards
Add 1.0, 2.5, 5.0, 12.5, 25.0, 37.5, 50.0, 75.0, and 100.0 mL of Cl Primary Standard to separate 1.0 L volumetric flasks and dilute to volume with Reagent Water. These solutions contain 2.0, 5.0, 10.0, 25.0, 50.0, 75.0, 100, 150, and 200 mg Cl–/L.
Analyse a filtered (≤0.45 μm pre-washed membrane and preferably ≤0.20 μm) aliquot of the SE and an appropriate range of Cl Working Standards by ICPAES for Cl– at a wavelength of 134.724 nm, as broadly outlined in Method 5A4. Soluble cations and other anions may also be determined simultaneously or sequentially. Dilute SE if necessary and record the dilution ratio, typically 1:10 for SE concentrations >200 mg Cl–/L.
Report Cl–/SE concentrations with the relevant method codes and units as detailed in Method 14E2a.