Interferences - Hach POCKET COLORIMETER II Instruction Manual

Interferences

Interfering Substance Interference Levels and Treatments
Monochloramine
See additional Interferences on page
Chlorine, Free and Total, HR,
For conventional free chlorine disinfection (beyond the
breakpoint), monochloramine concentrations are very low. If
monochloramine is present in the sample, its interference in the
free chlorine test varies with the temperature, the relative
amount of monochloramine to free ammonia, and the time
required to do the analysis. Approximate interference levels of
monochloramine in the free chlorine test are listed below (as
mg/L Cl ).
2
NH Cl
2
(as Cl ) 5 (40)
2
1.2 0.2
2.5 0.4
3.5 0.5
1—29.
1—41
Sample Temperature °C (°F)
10 (50) 20 (68)
0.2
0.5
0.6
continued
30 (83)
0.3 0.3
0.6 0.6
0.7 0.8