2. HPLC Monitor
FlowStar2 LB 514
20
2.1 Measuring Cell Module
The measuring cells are designed as modules and are therefore easy to
replace. They are inserted into the instrument from the front and fixed by
two screws.
Each measuring cell includes a chip that offers two functions:
When it is inserted, it automatically established contact when the meas-
uring cell is fixed with screws, and cuts the contact again as soon as
the screws of the measuring cell are released. This ensures that the
high voltage is turned on only when the counting chamber is closed.
It informs the system about the parameters of the measuring cell. This
ensures that only methods can be used during a run which are suitable
for this measuring cell.
An O-ring seals off light. The measuring cell itself is usually a spiral-shaped
thin Teflon hose through which the eluate is flowing. The radioactive la-
beled substances in the eluate flow are detected by means of scintillator,
either solid scintillator, located stationary in the measuring cell, or liquid
scintillator which is added to the eluate. The measuring cell is located be-
tween the photo cathodes of two photomultipliers operating in coincidence.
Depending on the measuring method either
solid cells (YG-cells),
admixture cells (Z) or
cells for Gamma or Cerenkov radiation (BGO, J, MX, or Z cells)
can be employed in different volumes.
Automatic settings
The nuclide and further parameters are entered in the dialog mode. Then
– depending on the measuring cell used – the coincidence time is set ac-
cording to the decay time of the scintillator used (±100 ns for solid and ±30
ns for liquid scintillator) and the corresponding energy window is activated.
