19
(8)
Open
the
HP ALKANE TO BOOSTER
and pump
OUTLET
valves to
depressurize the gas booster. This will push out the ethane in the gas booster back
into the syringe pump. Dependent on the pump fill factor and the initial CO
2
head
pressure, the pressure in the syringe pump will be around 1,500 psi. The system is
now filled with sufficient ethane to make fifteen typical ethane samples with
encapsulation pressures of 4,000 psi The CO
2
in the gas booster will need to be
recharged after each sample. This will be addressed later when the protocol for
transferring the sample and resetting the system is outlined.
THE MIXING CHAMBER / ADDING REAGENTS
The internal volume of the mixing chamber is approximately 1.65 ml when fully
assembled. There are slight variations between cells so an exact measurement
should be obtained using the syringe pump (see CALIBRATING THE SYSTEM). Of
this volume approximately 1.1 ml can be displaced by the piston. The dead volume
is comprised of the empty volume of the connection tubing empty, the reagent plate
well, and spaces created from placing windows in the mixing chamber walls. This
large available sample volume is required because the NMR cell has an active
volume of approximately 1.2 ml. There are two observation windows in the walls of
the chamber. The lamp abuts the back facing window, while the front facing window
is for observation of the sample preparation process.
In addition to the main mixing chamber body and top cap there are three additional
components as shown in Figure 10. These are the piston, the reagent plate, and o-
ring seal (MCCS).
Figure 10: Mixing chamber components:
Poston, reagent plate, and main seal (MCCS).