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11.5. IRON(II)/(III)
SPECIFICATIONS
Range
0.00 to 6.00 mg/L (as Fe)
Resolution
0.01 mg/L
Accuracy
±0.10 mg/L ±2% of reading at 25 °C
Light Source
LED with narrow band interference filter @ 525 nm
Method
Adaptation of Standard Methods for the Examination of Water and
Wastewater, 23
REQUIRED REAGENTS
Code
Description
HI96777A-0
Iron(II)/(III) Reagent A
HI96777B-0
Iron(II)/(III) Reagent B
REAGENTS SETS
HI96777-01
Reagents for 100 tests
HI96777-03
Reagents for 300 tests
For other accessories see ACCESSORIES section.
PRINCIPLE
During the first measurement, ferrous iron (Fe
red complex. During the second measurement, ferric iron (Fe
the addition of Reagent B; the resulting measurement is the sum of ferrous (Fe
iron.
APPLICATION
Surface water, drinking water, mineral and groundwater, process control
SIGNIFICANCE & USE
Surface water typically contains up to 0.7 mg/L of iron. Drinking water typically contains up to 0.3 mg/L
of iron, but this level may increase significantly if plumbing fixtures contain iron. In well-oxygenated,
non-acidic waters, iron exists mainly in the ferric form (Fe
(FeO(OH)). However, anoxic water may have high levels of dissolved ferrous iron (Fe
precipitate in heating/cooling systems or other equipment after exposure to air.
The Iron(II)/(III) method can be used to distinguish between the ferrous (Fe
forms of iron in a 2-step measurement process.
rd
Edition, 3500-Fe B, Phenanthroline Method
Quantity
1 packet
1 packet
2+
) reacts with 1,10-phenanthroline to form an orange-
3+
) is converted to ferrous iron (Fe
3+
) and will precipitate as iron oxide hydroxide
2+
) by
2+
3+
) and ferric (Fe
)
2+
) which could
2+
3+
) and ferric (Fe
)
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