Spectrophotometric determination with lanthanum alizarin complexone, directly or following steam acid distillation

1 Spectrophotometric determination with lanthanum alizarin complexone, directly or following steam acid distillation 

After concentration, if required, by steam acid distillation, the fluoride taken up in 0.1 m sodium hydroxide solution is determined photometrically 

If the fluoride concentration is relatively high, approximately 0.5 mg of F /l or more, photometric determination can be carried out directly in the water sample (approx. 10 - 25 ml) without recourse to steam distillation. 

This applies in particular to routine determination in drinking water. Interferences due to other substances are to be expected only rarely in 

The method may also be applied to waters with lower concentrations by 

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