Teledyne ACCQPrep HP125 Installation And Operation Manual page 57

Bracketed Sample
Injection Sequence
1. The inject valve will be moved to bypass to prevent con-
tamination of the loop during the cleaning process.
2. Air is drawn into the probe to eliminate any remaining sol-
vent in the probe.
3. The probe is placed into the wash station. The wash station
pump will flush wash fluid over the exterior of the probe
while 10 mL of wash fluid is drawn into the probe to wash
the interior flow path. The probe syringe pump will use
half strokes to improve the rinsing of any tiny amounts of
compound that may be present due to the wash process.
Once again, the probe is moved up and down over the wash
station to shake off any excess liquid and to prevent the
contamination of other samples or collection tubes.
4. Air is drawn into the probe to eliminate the strong wash
solvent from the sample flow path.
1. During column equilibrium, the sample loop is first placed
into the run position. This position passes the column
equilibration fluid through the loop to wash out any left-
over fluid from a previous separation and fills the loop with
the initial gradient conditions from the current separation.
This prevents any strong solvent remaining in the loop
from affecting the current separation.
2. The sample probe is placed into the wash station
3. About 1.5 mL of the solvent is pulled from the wash station
through the probe to remove air from the probe line. This
minimizes injection volume errors due to air in the probe.
Since the loop is still in the column flow path, this aspi-
rated fluid bypasses the loop and is sent to waste
4. The sample probe is lifted from the wash station and is
moved up and down slightly. When the sample probe is
dipped in the sample or solvent, some liquid sticks to the
outside of the probe when it is raised. Therefore, the probe
is moved up and down over the fluid source to shake off
any excess liquid and to prevent the contamination of other
samples or collection tubes.
5. A small amount of air (0.05 mL) is drawn into the sample
probe to minimize the mixing of the wash solvent and the
bracket solvent.
6. The probe moves to the bracket solvent sample station
(just to the left of the wash station). 0.05 mL of the bracket
solvent is aspirated into the probe.
7. The probe is raised into the air and an additional 0.05 mL
of air is aspirated into the probe.
8. The sample probe is moved to the sample container.
9. A portion of the programmed injection amount is aspirated
into the sample probe displacing most of the wash solvent
remaining in the sample probe. This compensates for the
ACCQPrep HP125
Section 4 Operation
4-11