Metrohm 882 Compact IC plus – Anion - Manual (Page 28)

3.5 Capillary connections in the IC system ￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭
18 ￭￭￭￭￭￭￭￭ 882 Compact IC plus – Anion
Capillary connections
In order to achieve optimum analysis results, capillary connections in an IC
system must be absolutely tight and free of dead volume. Dead volume
occurs if two capillary ends connected to each other do not fit exactly,
thus allowing liquid to escape. There are two possible reasons for this:
￭ The capillaries do not have exactly cut edges.
￭ The two capillary ends do not completely meet.
One prerequisite for dead volume free capillary connection is, that both
capillary ends are cut exactly plane. Therefore we recommend only to cut
PEEK capillaries with the capillary cutter (6.2621.080).
Creating dead volume free capillary connections
To create dead volume free capillary connections, proceed as follows:
1 Slide the pressure screw over the capillary. Ensure that the capillary
protrudes 1–2 mm from the tip of the pressure screw.
2 Plug the capillary all the way into the connection or coupling until
the stop.
3 Only then start turning the pressure screw, while keeping the capil-
lary pressed in space.
Colored sleeves for PEEK capillaries
The enclosed set of varicolored sleeves for PEEK capillaries (6.2251.000)
serves to easily differentiate the various flows of liquid in the system
through color coding. Each capillary leading a given liquid (e. g. eluent)
can be highlighted with sleeves of the same color.
To highlight a capillary, proceed as follows:
1 Slide a sleeve of a selected color over a capillary an move it to an
easily visible position.
If the capillary heats up, the sleeve shrinks and adapts to the form of
the capillary.