12 Redox/ORP Electrode User Guide
Table 2– Typical Redox Titration Methods
Unknown Interferences
antimony (Sb+3) As, Fe, SO2, V, and organic
substances
arsenic (As+3) other reducing agents
hydrogen peroxide
(H2O2)
preservatives present in commercial
H2O2 may interfere
hypochlorite ion (ClO¯)
or chlorine (Cl2)
Br2 and other oxidizing agents
interfere by liberating I2
iodine (I2) other reducing agents
iodine (I2) direct sunlight, high acidity, copper
salts and other catalysts promote air
oxidation and cause false high results
iron (as Fe+2, Fe+3
or in steel)
high levels of organic acids, such as
acetic, oxalic, tartaric, and alcohols;
F¯ if present in more than trace
amounts; Cl¯, PO4-3 (remove by
adding acid)
iron (as Fe+2, Fe+3
or in steel)
other reducing agents
manganese (as
permanganate Mn04¯)
other oxidizing agents
manganese (as Mn+2) other reducing agents
stannous tin (Sn+2) other reducing agents
sulfur (as sulfur
dioxide SO2)
S-2 and SO2-2 , remove by shaking
with CdCO3 and filtering
thallium (Ti+) other reducing agents
thiosulfate ion
(S2O3 -2)
S-2 and SO2 -2 , remove by shaking
with CdCO3 and filtering
uranium (as uranyl ion
UO+2)
other reducing agents
Zinc (Zn+2)
other reducing agents