10
1 Introduction to the Autosampler
Sampling Sequence
Sampling Sequence
The movements of the autosampler components during the sampling sequence
are monitored continuously by the autosampler processor. The processor
defines specific time windows and mechanical ranges for each movement. If a
specific step of the sampling sequence can’t be completed successfully, an
error message is generated.
Solvent is bypassed from the autosamplers by the injection valve during the
sampling sequence. The sample vial is selected by a gripper arm from a static
sample rack, or from external vial positions. The gripper arm places the
sample vial below the injection needle. The required volume of sample is
drawn into the sample loop by the metering device. Sample is applied to the
column when the injection valve returns to the mainpass position at the end of
the sampling sequence.
The sampling sequence occurs in the following order:
1 The injection valve switches to the bypass position.
2 The plunger of the metering device moves to the initialization position.
3 The gripper arm moves from the home position, and selects the vial. At the
same time, the needle lifts out of the seat.
4 The gripper arm places the vial below the needle.
5 The needle lowers into the vial.
6 The metering device draws the defined sample volume.
7 The needle lifts out of the vial.
8 If the automated needle wash is selected (see “Using the Automated Needle
Wash” on page 63), the gripper arm replaces the sample vial, positions the
wash vial below the needle, lowers the needle into the vial, then lifts the
needle out of the wash vial.
9 The gripper arm checks if the safety flap is in position.
10 The gripper arm replaces the vial, and returns to the home position.
Simultaneously, the needle lowers into the seat.
11 The injection valve switches to the mainpass position.
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