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WP
PotentiaMeter
4C
6. Sample Preparation
Preparing the Sample
To prepare a sample, follow these steps:
1. Place the sample in a disposable sample cup, com-
pletely covering the bottom of the cup, if possible.
WP4C may not be able to accurately measure a sample
that does not (or cannot) cover the bottom of the cup.
A larger sample surface area speeds up the reading by
shortening the time needed to reach vapor equilibrium.
It also increases instrument accuracy by providing more
stable infrared sample temperature measurements.
2. Do not fill the sample cup more than half full.
Overfilled cups may contaminate the sensors in
the chamber (more is not necessarily better!)
3. Make sure that the rim and outside of the sample
cup are clean. Wipe any excess sample material from
the rim of the cup with a clean tissue. Material left on
the rim or the outside of the cup will contaminate the
sensor chamber and will be transferred to subsequent
samples. The rim of the cup forms a vapor seal with
the sensor block when the drawer knob is turned to
the READ position. Therefore, any sample material
left on the cup rim will be transferred to the block,
preventing this seal and contaminating future samples.
4. If a sample will be read at some future time, put
the sample cup's disposable lid on the cup to
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