User Guide

Iodine demand of certain samples can cause a shift of the

end point as shown in the following graph:

The iodine, formed in case of forward total chlorine determi-

nation or added as titrant during the backward titration, can

be absorbed by suspended particles or can react with or-

ganic matter. This type of interference is common in the case

of muddy or highly organic-rich samples.

Another source of error is due to the tendency of some metal

to poison the electrodes of the titrator. Iron, copper, silver

and some other species can plate or coat the platinum probe

electrodes and diminish the probe response. Therefore the

dual platinum electrode (DPE) has to be cleaned regularly

(see electrode cleaning procedure on page 23).