Precise Injection Volume; Draw And Eject Speed - Agilent Technologies G1367A Reference Manual

Precise Injection Volume

Injection Volumes Less Than 2 µl
When the injection valve switches to the BYPASS position, the mobile phase in
the sample loop is depressurized. When the syringe begins drawing sample,
the mobile phase is further subjected to decreasing pressure. If the mobile
phase is not adequately degassed, small gas bubbles may form in the sample
loop during the injection sequence. When using injection volumes < 2 µl, these
gas bubbles may affect the injection-volume precision. For best
injection-volume precision with injection volumes < 2 µl, use of the
Agilent 1100 Series degasser is recommended to ensure the mobile phase is
adequately degassed. Also, using the automated needle wash (see
"Optimization for Lowest Carry-over"
carry-over to a minimum, improving injection-volume precision further.

Draw and Eject Speed

Draw Speed
The speed at which the metering unit draws sample out of the vial may have an
influence on the injection volume precision when using viscous samples. If the
draw speed is too high, air bubbles may form in the sample plug, affecting
precision. The default draw speed is suitable for the majority of applications,
however, when using viscous samples, set the draw speed to lower speed for
optimum results. A "DRAW" statement in an injector program also uses the
draw speed setting which is configured for the well plate sampler.
Eject Speed
The default draw speed is suitable for the majority of applications. When using
large injection volumes, setting the eject speed to a higher value speeds up the
injection cycle by shortening the time the metering unit requires to eject
solvent at the beginning of the injection cycle (when the plunger returns to the
home position).
An "EJECT" statement in an injector program also uses the eject speed setting
which is configured for the well plate sampler. A faster eject speed shortens
the time required to run the injector program. When using viscous samples, a
high eject speed should be avoided.
1100 Series WS MWS Reference Manual
Optimizing Performance
on page 45) between injections reduces
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