| Possible
coexisting substances and their interferences |
Substance
|
Concentration
|
Interference |
Change
color by itself |
Fe2+
|
0.5mg/l or lower
|
Minus error
|
Discolor reddish
purple from 0.5 mg/l |
Fe3+
|
1 mg/l or higher
|
Minus error
|
No discoloration
by 100 mg/l |
Cu
|
0.5 mg/ or lower
|
Plus error
|
Discolor reddish
purple from 0.5 mg/l |
Zn
|
0.5 mg/l or higher
|
Plus error |
Discolors purple
stain from 0.2 mg/l |
Mn
|
1 mg/l or higher
|
Plus error |
Discolors bluish
purple from 1 mg/l |
Al
|
0.5 mg/l or higher
|
Plus error |
No stain by 100
mg/l |
Ni
|
0.3 mg/l or higher
|
Plus error |
Discolor purple
stain from 0.3 mg/l |
Co
|
0.2 mg/l or higher
|
Plus error |
Discolors purple
stain from 0.2 mg/l |
