Selecting Parameters For The S/Sl Splitless Mode - Agilent Technologies 7890 Series Advanced Operation Manual

3
Inlets

Selecting parameters for the S/SL splitless mode

52
If a column in the flow path is not defined
Press [Front Inlet] or [Back Inlet].
1
Set the inlet temperature.
2
Set Total flow into the inlet. It must exceed your intended
3
Septum Purge flow. Measure the split vent flow using a
flow meter.
Subtract split vent flow and septum purge flow (see
4
Run and Prep Run"
column flow.
Calculate the split ratio (split vent flow/column flow).
5
Adjust as needed.
A successful splitless injection consists of these steps:
Vaporize the sample and solvent in a heated inlet.
1
Use a low flow and low oven temperature to create a
2
solvent- saturated zone at the head of the column.
Use this zone to trap and reconcentrate the sample at the
3
head of the column.
Wait until all, or at least most, of the sample has
4
transferred to the column. Then discard the remaining
vapor in the inlet—which is mostly solvent—by opening a
purge valve. This eliminates the long solvent tail that this
vapor would otherwise cause.
Raise the oven temperature to release the solvent and
5
then the sample from the head of the column.
Some experimentation is needed to refine the operating
conditions. Table 9 provides starting values for the critical
parameters.
Table 9 Splitless mode inlet parameters
Parameter Allowed setpoint range
No cryo, 24 °C to 450 °C
Oven temperature
CO
N
Oven initial time 0 to 999.9 minutes
Inlet purge time 0 to 999.9 minutes
on page 40) from Total flow to get
cryo, –60 °C to 450 °C
2
cryo, –80 °C to 450 °C
2
Advanced Operation Manual
"Pre
Suggested starting
value
10 °C below solvent
boiling point
≥ Inlet purge time
2 x Liner volume
Column flow