Selecting Parameters For The S/Sl Splitless Mode; Setting Parameters For The S/Sl Splitless Mode - Agilent Technologies 7820A Advanced User's Manual

3
Inlets

Selecting parameters for the S/SL splitless mode

Setting parameters for the S/SL splitless mode

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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.
3 Use this zone to trap and reconcentrate the sample at the
head of the column.
Wait until all, or at least most, of the sample has transferred
4
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 6 provides starting values for the critical
parameters.
Table 6 Splitless mode inlet parameters
Parameter Allowed setpoint range
24 C to 425 C
Oven temperature
Oven initial time 0 to 999.9 minutes
Inlet purge time 0 to 999.9 minutes
*
Gas saver time 0 to 999.9 minutes
Gas saver flow 15 to 1000 mL/min
* Gas saver is not supported on EPR (electronic pneumatics regulation) equipped GCs.
Mode The current operating mode—splitless
Oven temperature Below solvent boiling point
Temperature Actual and setpoint inlet temperatures
Suggested starting
value
10 °C below solvent
boiling point
Inlet purge time
2 x Liner volume
Column flow
After purge time
15 mL/min greater than
maximum column flow
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