Agilent Technologies G1313A, Reference Manual

Page: 42 / 292

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Optimizing Performance
Optimization for Lowest Carry-over
Injector Program with Needle Wash
The injector program includes the command NEEDLE WASH. When this
command is included in the injector program, the needle is lowered once into
the specified wash vial before injection.
For example:
1 DRAW 5 µl
2 NEEDLE WASH vial 7
3 INJECT
Line 1 draws 5 µl from the current sample vial. Line 2 moves the needle to vial
7. Line 3 injects the sample (valve switches to main pass).
Using an Injector Program
The process is based on a program that switches the bypass grove of the
injection valve into the flow line for cleaning. This switching event is
performed at the end of the equilibration time to ensure that the bypass grove
is filled with the start concentration of the mobile phase. Otherwise the
separation could be influenced, especially if microbore columns are used.
For example:
Outside wash of needle before injection: 14 sec. using flush port
Injector program:
Draw x.x (y) µl from sample
Needle wash as method
Inject
Wait (equilibration time - see text above)
Valve bypass
Wait 0.2 min
Valve mainpass
Valve bypass
Valve mainpass