Iron test - bipyridyl method – LaMotte DCL-20 Colorimeter User Manual
Page 16
IRON TEST - BIPYRIDYL METHOD
QUANTITY
CONTENTS
CODE
30 mL
*Iron Reagent #1
*V-4450-G
5 g
*Iron Reagent #2 Powder
*V-4451-C
1
Pipet, 0.5 mL
0353
1
Spoon, 0.1 g
0699
*WARNING: Reagents marked with a * are considered hazardous substances. Material Safety Data Sheets (MSDS) are
supplied for these reagents. For your safety, read label and accompanying MSDS before using.
Iron is essential to the formation of chlorophyll, and iron deficiency causes chlorosis. While most soils contain abundant
iron, only a fraction is soluble and readily available to the growing plant. This is particularly true in neutral or alkaline soils.
Acid soils contain higher levels of available iron.
RANGE:
0-25 ppm
METHOD:
Fer ric iron is re duced to fer rous iron and sub se quently forms a col ored com plex with bipyridyl for
a quan ti ta tive mea sure of to tal iron.
IN TER FER ENCES:
Strong ox i diz ing agents in ter fere, as well as cop per and co balt in ex cess of 5.0 mg/L
PROCEDURE
1. Fill a clean colorimeter tube (0967) to the 10 mL line with the soil filtrate then neutralize according to the procedure
on page 10.
2. Select setting 3 on the “Select Wavelength” knob. Press the “30 Second Read” button.
3. Insert tube containing sample into chamber and adjust to “100"%T with the ”Set Blank" knob. This is the 100%T
blank.
4. Remove the tube from the chamber. With 0.5 mL pipet (0353) add one measure of *Iron Reagent #1 (4450) to sample.
Cap and mix.
5. With the 0.1 g spoon (0699) add one level measure of *Iron Reagent #2 Powder (4451) to sample. Cap and shake
vigorously for 30 seconds.
6. Allow three minutes for maximum color development.
7. After three minutes, insert sample into colorimeter chamber, press the “30 Second Read” button and measure %T as
soon as reading stabilizes.
8. Consult the calibration chart to find the concentration of Iron in parts per million (ppm).
IRON CALIBRATION CHART (PPM)
%T
9
8
7
6
5
4
3
2
1
0
90
0.1
0.2
0.3
0.4
0.4
0.5
0.6
0.7
0.8
0.9
80
1.0
1.1
1.2
1.3
1.4
1.5
1.6
1.7
1.8
2.0
70
2.1
2.2
2.3
2.4
2.5
2.6
2.8
2.9
3.0
3.1
60
3.3
3.4
3.5
3.7
3.8
3.9
4.1
4.2
4.4
4.5
50
4.6
4.8
5.0
5.1
5.3
5.4
5.6
5.8
6.0
6.1
40
6.3
6.5
6.7
6.9
7.1
7.3
7.5
7.7
7.9
8.1
30
8.4
8.6
8.9
9.1
9.4
9.6
9.9
10.2
10.5
10.8
20
11.1
11.4
11.8
12.1
12.5
12.9
13.3
13.7
14.1
14.6
10
15.0
15.6
16.1
16.7
17.3
17.9
18.7
19.4
20.3
21.2
0
22.2
23.4
24.7
26.2
28.0
30.3
33.2
37.4
44.7
IRON CONCENTRATION CHART
%T
RANGE
PARTS PER MILLION
86-100%
Very Low
0-1.3 ppm
70-85%
Low
1.4-3 ppm
57-69%
Medium
3-5 ppm
32-56%
Medium High
5-10 ppm
0-31%
High
Above 10-25 ppm
16
1985-01 • 10/01