104 Agilent 1260 Infinity II Preparative Autosampler User Manual
6
Optimizing Performance
Precise Injection Volume
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 pressure of the mobile phase is decreased further. If the mobile phase is
not degassed adequately, small gas bubbles may form in the sample loop
during the injection sequence. When using injection volumes < 2 L, these gas
bubbles may affect the injection-volume precision. Use degassed mobile
phases for best injection-volume precision with injection volumes < 2 L.
If the pump has no degasser, it is recommended to use an Agilent 1260 Infinity
degasser.
Also, using the automated needle wash (see “Optimization for Lowest
Carry-over” on page 98) between injections reduces carry-over to a minimum,
further improving the injection volume precision.
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 100 L/min. This 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
autosampler.
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