Agilent Technologies Agilent 1260 Infinity System User's Manual page 16

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The Agilent 1260 Infinity Binary LC - Product Description
System Components
Injection Sequence
Before the start of the injection sequence, and during an analysis, the
injection valve is in the mainpass position. In this position, the mobile
phase flows through the autosampler metering device, sample loop, and
needle, ensuring all parts in contact with sample are flushed during the
run, thus minimizing carry- over.
When the sampling sequence begins, the valve unit switches to the bypass
position. Solvent from the pump enters the valve unit at port 1, and flows
directly to the column through port 6.
The final step of the sampling sequence 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.
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 that is located
behind the injector port on the sampling unit. As soon as 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.
16 1260 Infinity Binary LC - System User Guide