Notes On The Moisture Determination - Mettler Toledo DO307 Mode D'emploi

Notes
5.4

Notes on the moisture determination

1. Enter the time required to liberate the moisture from the sample on the titrator as a stirring time to
avoid premature termination of the titration (applies to volumetric titration). The liberation rate
depends on the sample.
2. You should avoid a flow rate higher than 250 mL/min. If you do not, the moisture introduced as
vapor would not be completely "trapped" by the titration solution, but would escape as gas from the
titration cell.
3. The tubing which supplies the gas must be immersed in the titration solution by at least
4 mm ! Introduction of the "hot" vapor into the titration cell causes evaporation of the volatile frac-
tion of the titration solution from the cell (within 8 hours up to 30 mL at an oven temperature of
200 °C and a gas flow rate of 200 mL/min).
• With coulometric titrations, you should thus always top up the anolyte solution, with volumetric
titrations with the particular solvent used.
4. For the DL32/DL39 Coulometer we advise replacing the straight drying tube of the generator elec-
trode by a bent drying tube (see Section 9.2: Optional equipment). This prevents any solvent
condensed on the drying tube from dripping into the catholyte.
12 DO307
METTLER TOLEDO