1.1 Methods
Notes:
1. For determination of total Iron digestion is required.
TPTZ reagent recovers most insoluble iron oxides without digestion.
2. Rinse all glassware with 1:1 Hydrochloric acid solution first and then rinse with deionised
water to remove iron deposits that can cause slightly high results.
3. Strong alkaline or acidic water samples must be adjusted between pH 3 and pH 8
before the reagent is added (use 0.5 mol/l Sulfuric acid resp. 1 mol/l Sodium hydroxide).
4. Interferences:
When interferences occur, colour development is inhibited or a precipitate is formed.
The values below refer to a standard with an iron concentration of 0.5 mg/l.
The following substances do not interfere when present up to the levels given:
Substance no inerference to
Cadmium 4.0 mg/l
Chromium
(3+)
0.25 mg/l
Chromium
(6+)
1.2 mg/l
Cobalt 0.05 mg/l
Copper 0.6 mg/l
Cyanide 2.8 mg/l
Manganese 50 mg/l
Mercury 0.4 mg/l
Molybdenum 4.0 mg/l
Nickel 1.0 mg/l
Nitrite Ion 0.8 mg/l
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