Development of Karl Fischer Reagents

Chapter II: Applications - 1
b) Titration flask D is cooled to -78 � C in a methanol dry ice cooling bath.
c) Immediately after the nitrogen flow has been stopped, the sample gas is
passed into titration flask D in the direction A � M � y at a rate of
approximately 0.5l/min.
d) When 5~20l of gas has passed through the system, the three-way cock is
switched to allow nitrogen to flow into titration flask D in the direction L �
M � y for about one minute to drive out all of the sample gas.
e) The flow of nitrogen is then stopped and 20ml of a 1:1 pyridine/methanol
solution is introduced from B to flush out the water that has condensed in
E.
f) Titration flask D is removed from the methanol dry ice cooling bath. When
the flask has returned to room temperature, the water captured in the
pyridine/methanol solution is titrated.
g) A dummy value is established from 20ml of pyridine/methanol solution
using the same procedures. Moisture content is determined by
subtracting this value from the titration result.
Dried
nitrogen gas
Hydrogen
chloride gas
Hydrogen
chloride gas Nitrogen gas
Figure 20: Titration Apparatus for Hydrogen Chloride Gas
A:Flowmeter for hydrogen
chloride gas
B: Solvent injection port
C: Cooling bath
D: Titration flask
E: Condensing tube
F: Nitrogen supply tube
G: Platinum electrode
H: Stirrer bar
I: Buret protector
J: Buret for KF reagent
K. Back-up titration flask
L,M,N: Three-way stop cocks
O,P: Drying tubes
117