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Principles of Operation
Sample Position in the Sample Loop
Ideally, the injection volume is injected exactly into the sample loop. In reality, the injection
volume is often slightly offset. Therefore, the front and rear volume are used to ensure the loop is
full with sample. This is illustrated schematically in Figure A-16, where:
•
Blue—air (front air gap and rear air gap)
•
Yellow—sample (rear volume)
•
Orange—sample (injection volume)
•
Pink—sample (front volume)
Even when the injection volume is not located exactly in the sample loop, the presence of the
front and rear volume ensures that the entire volume injected onto the column contains sample.
Figure A-16 Possible Locations of Sample in Loop, Front and Rear Volume >0
Sample Loop
Injection volume exactly in loop
Injection volume offset, rear volume follows sample
Injection volume offset, front volume precedes
sample
Flow
Because the front and rear volumes can be set to 0 by the user in the autosampler method in the
Analyst® software, it is possible that the volume injected onto the column can include an air
bubble. This is illustrated schematically in Figure A-17, where blue represents air and orange
represents the injection volume.
Figure A-17 Possible Locations of Sample in Loop, Front and Rear Volume = 0
Sample Loop
Injection volume exactly in loop
Injection volume offset, air bubble follows sample
Injection volume offset, air bubble precedes sample
Flow
Communicating with the DLW
The Analyst® software uses the autosampler method to communicate with the HTC-xt PAL
autosampler and the DLW. The autosampler method is part of the acquisition method.
The Available Cycles field in the CTC PAL Autosampler Basic Properties tab of the
Acquisition Method window (Figure A-18) lists the available autosampler methods. The
appropriate method for the HTC-xt PAL autosampler is “microLC200-Injection-Rev B” and is
installed with the Eksigent MicroLC 200 Plus system.
Eksigent MicroLC 200 Plus System
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Operator Guide
RUO-IDV-05-1129-B | D5033433 G