INJECTORS
OCPTV - On-Column ProgrammedTemperatureVaporization Injector
Theoryof Operation
Carrier EPC
(electronic
pressure
controller)
Carrier filter
On-column
injector
OCPTV
(Resistively heated pre-column)
To column
Split vent
solenoid
Split vent
needle
valve
Split vent exit
Flow splits
at âTâ
connection
The GC operator injects sample via syringe through the on-column injection port with the split vent
open tovent the solvent. After injectionand solvent venting, thepre-columnheatsupwhile thecarrier
gas flows through it to sweep focused analytes from the pre-column to the analytical column. At this
point, the pre-column is hotter than the column oven. The temperature difference between the hotter
pre-columnandcooleranalyticalcolumncauses theanalytes to focuson theanalyticalcolumn, resulting
in sharp peaks on the chromatogram.
The 5micron non-polar phase in theOCPTV pre-column has a high capacity to absorb high boiling
compounds, and is stable at high temperatures. Like in-tube SPME, the pre-column discriminates in
favor of high boiling semi-volatile analytes, concentrating them in the phase. Unlike a normal heated
split/splitless injector, the OCPTV vents the solvent without expanding it to a gas. Therefore, the
OCPTV can accommodate larger liquid injections than heated split/splitless injector.
Inside theTConnection -MagnifiedView
Pre-column
Analytical column
Split vent towaste
