Agilent Technologies G1367A, Reference Manual

Page: 203 / 286

Introduction to the Well-plate Sampler
6
1100 Series WS MWS Reference Manual 203
The standard injection starts with „draw sample from vial”. In order to do this
the needle moves to the desired sample vial position and is lowered into the
sample liquid in the vial to allow the metering device to draw up the desired
volume by moving its plunger back a certain distance. The needle is then
raised again and moved onto the seat to close the sample loop. In case of an
injector program several steps are interspersed at this point.
Flush the needle
Before injection and to reduce the carry-over for very sensitive analysis, the
outside of the needle can be washed in a flush port located behind the injector
port on the sampling unit. As soon the needle is on the flush port a peristaltic
pump delivers some solvent during a defined time to clean the outside of the
needle. At the end of this process the needle returns to the injection port.
Inject-and-run
The final step is the inject-and-run step. The six-port valve is switched to the
main-pass position, and directs the flow back through the sample loop, which
now contains a certain amount of sample. The solvent flow transports the
sample onto the column, and separation begins. This is the beginning of a
„run” within an analysis. In this stage, all major performance-influencing
hardware is flushed internally by the solvent flow. For standard applications
no additional flushing procedure is required.
Figure 33 Drawing the Sample