52 Advanced Operation Manual
3 Inlets
If a column in the flow path is not defined
1 Press [Front Inlet] or [Back Inlet].
2 Set the inlet temperature.
3 Set Total flow into the inlet. It must exceed your intended
Septum Purge flow. Measure the split vent flow using a
flow meter.
4 Subtract split vent flow and septum purge flow (see “Pre
Run and Prep Run” on page 40) from Total flow to get
column flow.
5 Calculate the split ratio (split vent flow/column flow).
Adjust as needed.
Selecting parameters for the S/SL splitless mode
A successful splitless injection consists of these steps:
1 Vaporize the sample and solvent in a heated inlet.
2 Use a low flow and low oven temperature to create a
solvent- saturated zone at the head of the column.
3 Use this zone to trap and reconcentrate the sample at the
head of the column.
4 Wait until all, or at least most, of the sample has
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.
5 Raise the oven temperature to release the solvent and
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.
Tabl e 9 Splitless mode inlet parameters
Parameter Allowed setpoint range Suggested starting
value
Oven temperature No cryo, 24 °C to 450 °C
CO
2
cryo, –60 °C to 450 °C
N
2
cryo, –80 °C to 450 °C
10 °C below solvent
boiling point
Oven initial time 0 to 999.9 minutes ≥ Inlet purge time
Inlet purge time 0 to 999.9 minutes 2 x Liner volume
Column flow
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