136 Advanced Operation Manual
3 Inlets
Setting parameters for the VI splitless mode
Mode: The current operating mode—splitless
Tempera ture Actual and setpoint interface temperatures.
Column temperature must be low enough to cold trap the
volatile sample. Cryo focussing is recommended.
Sampling end The sample introduction interval, in minutes.
The flow rate is calculated from the pressure setpoint that is
active at the start of sample introduction.
Set the sampling end setpoint 0.2 minutes longer than the
time the sampler needs to introduce the sample. For
example, the 7694 headspace sampler has an Inject time
parameter which controls how long the valve remains in the
inject position. If Inject time is 1 minute, the sampling end
setpoint should be set to 1.2 minutes. If you’re using an
7695 Purge and Trap Concentrator, set Sampling end
0.2 minutes longer than the Desorb time parameter.
If your column is defined and you specify a flow or pressure
program for your column, the ramp does not begin until
after the sampling end setpoint expires.
Pressure Actual and setpoint interface pressure in psi, bar,
or kPa.
Purge time The time, after the beginning of the run, when
purging resumes. Purge time must be greater than Sampl’g end.
Tabl e 35 Suggested starting values
Parameter Allowed setpoint range Suggested starting
value
Oven initial time 0 to 999.9 minutes ≥ Interface purge time
Interface temperature Ambient + 10 °C to 400 °C ≥ Transfer line
temperature
Interface sampling end 0 to 999.9 minutes 0.2 minutes longer than
introduction time
Interface purge time 0 to 999.9 minutes
Gas saver time 0 to 999.9 minutes Must be after purge time
Gas saver flow 15 to 100 mL/min 15 mL/min greater than
maximum column flow
To Next Page
Loading...
Need help?
General
