Development of Karl Fischer Reagents

3. Sugars and Condiments
Key Points
Chapter III: Applications - 2
Sugars are dissolved in a sugar-type dehydrated solvent and titrated.
Volumetric titration is used. If a substance is slow or difficult to dissolve
the solvent can be heated (up to 50 � C) and titrated. (If the temperature
exceeds 50 � C the formamide in the sugar-type dehydrated solvent will
gradually break down. The Karl Fischer reagent will be consumed in
small amounts leading to uncertainty about the end point.)
Condiments are normally dispersed in general-use dehydrated solvent.
This is followed by extraction and titration. If the ingredients of a
particular item give it a high sugar content, a sugar-type dehydrated
solvent is used. An oil-type dehydrated solvent is used for products with
a high fat content.
Moisture vaporization should generally be avoided for sugars as these
tend to break down when heated. Moisture vaporization is unnecessary
for condiments, since in almost all cases moisture content can be
measured using direct titration. When using the moisture vaporization
method the optimal heating temperature must be determined first.
Changes in the sample could lead to errors.
[Examples of Measurement]
(1) Volumetric titration
Reagents used: Karl Fischer Reagent SS-Z (or SS)
Dehydrated Solvent GEX, SU, OL II (or MS, FM) 25-50ml
Substance
Dehydrated
solvents
Sample Quantity
(g)
Measurement Value
(mg)
Moisture Content
(%)
Wasabi paste General-use 0.0465 10.23 22.0
Roast meat gravy " 0.0187 10.66 57.0
Soy sauce " 0.0265 17.55 66.2
Soup powder " 0.0754 2.89 3.83
Bonito stock " 0.1475 7.48 5.07
Sugar syrup " 0.0691 40.56 58.7
Powdered miso " 0.1228 3.79 3.09
Glucose Sugar-type 1.1052 1.64 0.148
White sugar " 0.2550 3.51 1.38
Maltose " 0.0695 3.56 5.12
Malt syrup " 0.0505 12.49 24.9
Soup " 0.0322 19.87 61.7
Refined sugar Sugar-type (40 � C) 0.4729 4.04 0.854
Soup stock Sugar-type (40 � C) 0.4363 5.66 4.22
Granulated sugar Sugar-type (45 � C) 2.8133 0.71 252ppm
Mayonnaise Oil-type 0.1425 28.93 20.3
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