84
03-914648-00:7
The following table describes typical method parameters for an isothermal
splitless injection.
Table 10 Isothermal Splitless Injection Method Parameters
Injector Insert
Install the standard 3.4 mm ID splitless insert (P/N 03-926119-45).
Column Position
7.5 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.
Temperature
Ramped
Splitless
Injection
This is a similar technique to isothermal splitless except the sample is
vaporized slowly, utilizing temperature programming. This controlled
mode of vaporization reduces the risk of mass discrimination and thermal
breakdown of sample components during the sampling period. The
sample is deposited in the injector as a liquid, therefore the initial injector
temperature must be close to the solvent boiling point and there must be a
nearby surface for the sample to be retained on. For this mode of injection
either a narrow bore (0.5 mm) insert or a glass wool packed insert is used.
This facilitates efficient transfer of the sample to a surface from which it is
then vaporized.
Note that the glass wool packet insert is not recommended for low levels of
polar analytes.
The following are typical method parameters for a temperature ramped
splitless injection. In this example hexane is used as the solvent which has
a boiling point of 68 °C. Note that the sampling time and initial column hold
time are 2 minutes to allow the injector get to maximum temperature.
Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com
