Development of Karl Fischer Reagents

II-1. Organic Compounds
3. Alcohols
76
Key Points
The moisture content of alcohols can be measured easily using direct
titration. End-points are stable and highly accurate analytical results are
attainable. Both volumetric and coulometric titration can be used.
In the case of volumetric titration, the sample is dissolved in a generaluse
dehydrated solvent and titrated. Alcohols dissolve very well in this
type of solvent and there should not be any problems. Solubility may be
inadequate with higher alcohols (such as stearyl alcohol). In such cases
it is appropriate to use dehydrated solvents formulated for use with oils.
Propargyl alcohol interferes with the titration by reacting with the Karl
Fischer reagent.
For coulometric titration, the sample is dissolved in the electrolyte
solution (anolyte). Titration will be prolonged if samples have a high
moisture content (2% or above). We recommend either the reduction of
the sample quantity, or the use of volumetric titration.
Examples of substances that can be measured directly:
-Monohydric alcohols-
Methanol, ethanol, isopropanol, alkyl alcohol, n-, iso-, tert-butanol, isoamyl
alcohol, 2-methyl-4-butanol, 2,4-dimethyl-3-pentanol, decanol, dodecanol,
octadecanol, geraniol, citronellol, cyclohexanol, borneol, terpinenol, benzyl
alcohol, cholesterol
-Polyhydric alcohols-
Ethylene glycol, 1,2-propanediol, 1,3-propanediol, glycerine, 1,4-butanediol,
1,4-butenediol, 2-methyl-1, 3-propanediol, diethylene glycol, pentaerythritol,
D-mannitol, D-sorbitol