| Possible
coexisting substances and their interferences |
Substance
|
Concentration
|
Interference |
Change
color by itself |
Zn-
|
20 mg/l or higher
|
Minus error
|
No stain by 1000
mg/l or lower |
Al
|
30 mg/l or higher
|
Minus error
|
No stain by 1000
mg/l |
Co
|
3 mg/l or higher
|
Plus error
|
Discolor greenish
brow by 20 mg/l |
CN--
|
10 mg/l or higher
|
Minus error |
No stain by 100
mg/l or higher |
Fe2+
|
5 mg/l or higher
|
Plus error |
Discolor brown
stain at 60 mg/l or higher |
Fe3+
|
100 mg/l or higher
|
Minus error |
No stain at 100
mg/l |
Cu
|
5 mg/l or higher |
Plus error |
Discolor reddish
brown / yellowish green |
