Development of Karl Fischer Reagents

Chapter II: Applications - 1
Substances that react with electrodes or cause other interference
reactions
Coulometric titration cannot be used for substances that react with
electrodes, such as aniline, toluidine, diamines and aminophenol.
With substances such as aniline or toluidine, the end point will not be clear if
methanol is used as the titration solvent for volumetric titration. Volumetric
titration is possible, provided that Dehydrated Solvent CP is used. Diamines
cause an interference reaction with iodine, with the result that the end point
is never reached.
Reference:(1) Muroi, K. et al., "Measuring Trace Moisture Content in
Amines Using the Karl Fischer Method" (in Bunseki Kiki
[Analytical Equipment] 8, 374, 1969).
(2) Kato, H. et al., "Determination of Moisture in Amines by Karl
Fischer Coulometric Titration" (in Bunseki Kagaku 34, 805
(1985).
Examples of substances that can be measured directly using standard
methods:
Pyridine, 2-aminopyridine, 2-picoline, quinoline, pyrrole, imidazole, triazine,
triazole, indole, carbazole, benzothiazole, N,N-dimethylaniline,
diphenylamine, 2-pyridyl ethanol, 4-pyridyl ethanol
Examples of substances that require neutralization with acid:
Trimethylamine, ethylamine, diethylamine, triethylamine, propylamine,
isopropylamine, 3-methoxypropylamine, butylamine, di-isobutylamine, disec-butylamine,
dipentylamine, hexylamine, N,N-dimethylcyclohexylamine,
dicyclohexylamine, benzylamine, pyrrolidine, piperidine, piperazine,
morpholine, ethanolamine, N,N-dimethylethanolamine, diethanolamine,
triethanolamine, di-isopropanolamine, tri-isopropanolamine, Tris
(hydroxymethyl) aminomethane
Examples of substances that require a methanol-free titration solvent:
Aniline, toluidine, anisidine, naphthylamine
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