Thermo Scientific AQUAfast AQ3700, User Manual

Page: 107 / 264

0
Thermo Scientific Orion AQUAfast AQ3700 Colorimeter User Guide
1.1 Methods
Notes:
Digestion procedure for the determination of total soluble and insoluble iron.
1. Add 1 ml of concentrated sulfuric acid to 100 ml water sample. Heat and boil for 10
minutes or until all particles are dissolved. After cooling down, the sample is set to a
pH-value of 3 to 6 by using ammonia solution. Refill with deionized water to the
previous volume of 100 ml and mix well. 10 ml of this pre-treated solution is used for
the following analysis. Perform as described by the selected test method.
2. Water which has been treated with organic compounds like corrosion inhibitors must
be oxidized where necessary to break down the iron. Therefore add 1 ml concentrated
sulfuric acid and 1 ml concentrated nitric acid to 100 ml water sample and boil to
approx. half volume. After cooling down, proceed as described above.
result B result A minus
= Fe 3+
Fe
2+
+ Fe
3+
Fe
2+
Fe
2+
+ Fe
3+
IRON LR
tablet
IRON (II) LR
tablet
methods
220, 222, 223
soluble Iron
soluble and insoluble
Iron
Filtration Digestion
Iron Determination