44 Agilent 1200 Series Autosampler Reference Manual
2 Optimizing Performance
Optimization for Lowest Carry-over
Several parts of an injection system can contribute to carry-over:
• needle outside
• needle inside
• needle seat
• sample loop
• seat capillary
• injection valve
The autosampler continuous flow-through design ensures that sample loop,
needle inside, seat capillary, and the mainpass of the injection valve is always
in the flow line. These parts are continuously flushed during an isocratic and
also during a gradient analysis. The residual amount of sample remaining on
the outside of the needle after injection may contribute to carry-over in some
instances. When using small injection volumes or when injecting samples of
low concentration immediately after samples of high concentration, carry-over
may become noticeable. Using the automated needle wash enables the
carry-over to be minimized and prevents also contamination of the needle
seat.
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