FerroVer® Method
Iron exists in two states in solution-the ferrous and ferric forms. The iron test described here measures the soluble and
most precipitated forms of iron; both ferrous and ferric iron are detected.
Iron may be present in the water sample because it was present in the water supply, or it may be due to system
corrosion. Therefore, interpretation of iron results must address the factors of both scale and corrosion. For example,
iron deposits can form in a cooling system as the result of a scale problem (deposition of the natural iron in the water)
or a corrosion problem (wasting away of the metal surfaces). Thus, iron determinations can reveal information on
either deposition or corrosion taking place within a system.
SUMMARY OF METHOD
FerroVer® iron reagent reacts with all soluble iron and most insoluble forms of iron in the sample to produce soluble
ferrous iron. This reacts with the 1,10-phenanthroline indicator in the reagent to form an orange color in proportion to
the iron concentration. This method was adapted from Standard Methods for the Examination of Water and
Wastewater, Federal Register, 45 (126), 433459 (June 27, 1980).
APPARATUS REQUIRED
Apparatus Betz Code
Cell, sample 25 mL, 2.5 cm (2 required) 2601
Clippers, large 2635
Cylinder, graduated, plastic, 25 mL 495
Flask, Erlenmeyer, glass, 50 mL 389
Pipet, plastic, 1 mL, graduated 371
Safety Bulb, rubber 1575
Spectrophotometer, DR 2000 2776
CHEMICALS REQUIRED
Chemical Betz Code
FerroVer® Iron Reagent Powder Pillow 2032
Iron, Standard Solution, 50 mg/L as Fe 523
RoVer® Rust Remover 2058
INTERFERENCES
The following will not interfere below the levels shown:
Chloride 185,000 mg/L
Calcium 10,000 mg/L as CaCO3
Magnesium 100,000 mg/L as CaCO3
A large excess of iron will inhibit color development. A diluted sample should be tested if there is any doubt about the
validity of a result.
FerroVer iron reagent powder pillows contain a masking agent that eliminates potential interference from copper.
Samples containing some forms of iron oxide require digestion in an acid and peroxide solution.
Samples containing large amounts of sulfide should be treated in a fume hood or well ventilated area as follows:
1. Add 5 mL of 50% hydrochloric acid (Betz Code 247) to 100 mL of sample and boil for 20 min.
2. Adjust the pH to between 2.5 and 5.0 with 5 N sodium hydroxide (Betz Code 2003).
3. Readjust the volume to 100 mL with deionized water.
4. Analyze as described below.
Highly buffered samples or extreme sample pH levels may exceed the buffering capacity of the reagent and require
sample pretreatment.
FerroVer iron reagent powder pillows are stable for up to 12 months, depending on storage and handling conditions. A
cool, dry atmosphere is recommended for long shelf life. To check the stability, add the contents of one powder pillow
to about 25 mL of water containing visual rust. If the characteristic orange color does not develop, the reagent has
deteriorated beyond use and should be discarded.
PROCEDURE FOR TEST
1. Using a graduated cylinder, transfer 25 mL of sample to an Erlenmeyer flask. Note: If the sample is turbid, add a
0.2 g scoop of RoVer® rust remover (Betz Code 2058) to 25 mL portions of the sample and blank, and wait 5 min.
Swirl to dissolve. Use the RoVer-containing blank to zero the instrument.
2. Add the contents of one FerroVer® iron reagent powder pillow and swirl to mix. An orange color will develop if iron
is present. Allow at least 3 min for the color to develop fully, but do not wait more than 30 min.
3. Turn on the spectrophotometer and set the wavelength at 510 nm.
4. Transfer a portion of unreacted sample to a clean sample cell. Place the cell in the spectrophotometer and set the
absorbance reading to zero.
5. Transfer the reacted sample (from step 2) to a clean sample cell, place it in the spectrophotometer, and read the
absorbance.
6. Use a previously prepared calibration curve to convert the absorbance reading to a concentration value.









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