Smartline Autosampler 3900 Manual / Handbuch V 1508 03/2007

Injection Principle 15
The AS 3900 uses a syringe to aspirate the sample from a vial into the
sample loop. To prevent contamination of the syringe the AS 3900 is
equipped with a buffer tubing between the syringe and the injection valve.
The wash solvent is used to remove the sample from the buffer tubing
and sample needle and rinse the buffer tubing and sample needle.
Full loop injections
The switching sequence for a full loop injection is schematically shown in
the following figures:
Fig. 5 Full loop injection: initial situation.
Fig. 6 Full loop injection: flushing sample lines and needle.
Fig. 7 Full loop injection: switch injection valve to LOAD.
The Initial situation: the injection
valve is in the INJECT position. The
sample needle with air needle has
entered the vial. The headspace
pressure, applied through the outer
air needle, ensures that no air or
vapour bubbles are formed during
sample aspiration.
The syringe dispenser aspirates the
“flush volume” from the sample vial
to fill the sample line with sample
and remove wash solvent.
The injection valve is switched into
the LOAD position, placing a distinct
sample front at the inlet of the
sample loop.
The sample loop is quantitatively
filled by transporting a number of
times the loop volume through the
loop, depending on the volume of the
loop.
3x loop volumes
for loops 500 µl