VISOCOLOR® Iron (DEV)
Determination of iron
	DEV procedure: iron(II) ions react with 1,10 phenanthroline to form an orange coloured complex. Iron(III) ions are reduced and thus also determined. Oxidising agents (H2O2, Cl2, CrO4 2–) interfere > 30 mmol/l, but can be eliminated with sodium sulphite or ascorbic acid. Complex iron compounds (hexacyanoferrates) are not determined unless they are decomposed with conc. sulphuric acid prior to the test.

Data and ordering information
Cat. No.	914 217
Type	refill pack
Range	0.1 0.3 0.5 1.0 2.0 4.0 7.0 10 25 50 mg/l Fe
Sufficient for	100 determinations
Shelf life	at least 3 years
Sea water suitability	yes
Detectable with PF-11	yes

Natural waters as well as waste waters often contain some iron. It can be present as Fe(II) or Fe(III) ions if the pH value of the water is below 3 or if the water is free of oxygen. At higher pH values Fe(III) forms an insoluble oxyhydrate. Frequently the sample is in a transition state with finely dispersed iron oxides. In waste water and natural water containing humic acids iron is often present in the form of a complex salt. The VISOCOLOR® test kits only determine iron which is present in dissolved form as Fe2+ or Fe3+ ions. Iron complexes are not covered unless they are decomposed by oxidation with nitric acid and sulphuric acid.