Varian 450-GC, User Manual

Page: 106 / 205

Injectors – 1177 Split/Splitless Capillary Injector
Page: 168 User Manual 450-GC Varian, Inc.
Splitless Injection
The classical splitless injection technique involves vaporizing the sample in a
hot Injector and slow transfer to the column. The split state is OFF during the
sampling period; therefore, all of the injected sample should enter the column.
The initial column temperature is maintained for at least the sampling time to
trap all sample components at the head of the column. At the end of the
sampling period (typically 0.5 to 1.5 minutes) the split state is turned ON to vent
any residual sample or solvent from the Injector.
The following table describes typical method parameters for an isothermal
splitless injection.
Injector Insert 4 mm ID open insert packed with glass wool.
Column Position 3.7 cm from the bottom of the column nut at the base of the Injector.
Injector Temperature
Initial temperature isothermal 250
°
C.
Column Temperature 50
°
C initial for 1 min, ramp to 250 °C at 20
°
C/min, hold 5 minutes.
Carrier gas control
Set the initial split mode to OFF and time program it to ON after 0.75
minutes. In this case the splitless sampling time is 0.75 minutes. The split
ratio during the split ON period should be set to 50. Set the appropriate
pressure or pressure ramp to achieve the desired column flow rate.
Table 30: Splitless Injection Method Parameters
Note that in all the above cases the parameters given are generic and need
optimization (including column position) for specific applications. Particular
care should be taken with the large volume mode of injection where the initial
Injector temperature and timing of the split states have to be carefully selected.